ccm/sff-papers · Datasets at Hugging Face

['Poudel, Arun', 'Sotani-Tehrani, Arash', 'Shao, Shuai', 'Shamsaei, Nima']

2021-12-06T22:07:14Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90691', 'http://dx.doi.org/10.26153/tsw/17610']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'tensile properties', 'powder characteristics', 'powder flowability', 'LB-PBF']

Effect of Powder Characteristics on Tensile Properties of Additively Manufactured 17-4 PH Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/351d7255-8b30-4bd2-9593-2b06b4b48030/download

University of Texas at Austin

Laser beam powder bed fusion (LB-PBF) process uses metallic powders as feedstock, whose particle characteristics such as cohesion, compressibility, size distribution, etc., can vary and affect the mechanical performance of the fabricated parts. In this study, two powder batches of 17-4 precipitation hardening (PH) stainless steel (SS) supplied by EOS (Batch 1) and Carpenter Technology (Batch 2) were used to fabricate specimens using identical process parameters to understand the effects of particle characteristics on defect content as well as tensile performance of the LB-PBF specimens. Higher cohesion and compressibility as well as lower sphericity in Batch 2 resulted in specimens with higher porosity levels. During tensile testing, the higher porosity level in Batch 2 yielded lower ductility. In contrast, the microstructure was observed to be less sensitive to particle characteristics because of which the tensile strengths of the specimens were found to be comparable to each other.

null

['Vunnam, S.', 'Dobson, S.', 'Saboo, A.', 'Frankel, D.', 'Sudbrack, C.', 'Starr, T.L.']

2021-11-18T00:06:37Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90364', 'http://dx.doi.org/10.26153/tsw/17285']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['17-4 PH stainless steel', 'selective laser melting', 'electron backscatter diffraction', 'EBSD', 'phase composition', 'mechanical properties', 'H900 hardening']

Effect of Powder Chemical Composition on Microstructures and Mechanical Properties of L-PBF Processed 17-4 PH Stainless Steel in the As-Built and Hardened-H900 Conditions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/924e6103-acec-42c1-8535-1d2e74efafb6/download

University of Texas at Austin

Post-build heat treatments such as solutionizing and precipitation hardening are recommended for selective laser melting (SLM) processed components to achieve a homogeneous microstructure. In this study, the effect of powder elemental composition on microstructures and mechanical properties of SLM processed 17-4 PH was studied in the as-built and precipitation hardened (H900) condition without prior solutionizing. Microstructural characterization demonstrated that H900 increased martensite phase composition for samples from powder with low chromium to nickel equivalent (Creq/Nieq) value, whereas no significant difference was observed for the samples from powders with high Creq/Nieq value. None of the specimens exhibited austenite reversion and strain hardening behavior in the as-built and H900 conditions. Low Creq/Nieq specimen exhibited higher yield and tensile strengths, and microhardness from H900, which are comparable to H900 wrought sample. However, no significant improvement in total elongation was observed other than uniform elongation for low Creq/Nieq specimen.

null

['Niino, Toshiki', 'Sato, Kazuki']

2021-09-28T19:21:48Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88159', 'http://dx.doi.org/10.26153/tsw/15100']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['powder compaction', 'plastic laser sintering fabrication']

Effect of Powder Compaction in Plastic Laser Sintering Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f757c9f8-faf6-4eb3-a499-114f378bb0e2/download

University of Texas at Austin

Powder compaction is introduced into plastic laser sintering fabrication. Compaction was carried out by using a roller of which rotation speed is independently controlled of its traversing speed. This additional process improved packing density of powder bed by a factor of 20% and reduced residual porosity of obtained parts by a factor of 30%. As an advantage, powder compaction can improve mechanical strength of parts of semi-crystalline powder, but increases excessive sinter to reduce fabrication accuracy especially in fabrication of amorphous plastic. This paper presents characteristics of the powder compaction process itself and its effects on performance of obtained parts.

null

['Carrion, Patricio E.', 'Soltani-Tehrani, Arash', 'Thompson, Scott M.', 'Shamsaei, Nima']

2021-11-11T15:05:48Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90212', 'http://dx.doi.org/10.26153/tsw/17133']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['laser-powder bed fusion', 'Ti-6Al-4V', 'fatigue life', 'powder degradation', 'powder recycling']

Effect of Powder Degradation on the Fatigue Behavior of Additively Manufactured As-Built Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9110d0df-b1ab-489b-8777-77cda3e9a761/download

University of Texas at Austin

Additive manufacturing (AM) technology has enabled many industries to generate functional parts with an increased level of complexity via a layer-by-layer melting. In laser-powder bed fusion (L-PBF), the most commonly used AM process for metals, powder is often recycled due to its high cost. However, there is no comprehensive study on how recycling powder affects its rheological properties, and the mechanical and fatigue behavior of the final manufactured part. In this study, a comparison of new and used Ti-6Al-4V powder characteristics was made. The comparison includes morphology, size distribution, as well as monotonic tensile and fatigue behavior of fabricated specimens. Conclusions and suggestions on powder recycling are made. Results indicate that the powder particle size distribution (PSD) becomes narrower and the morphology of the particles change with recycling. However, no comparable effect was observed on the monotonic tensile and fatigue behavior of the AM as-built Ti-6Al-4V specimens.

null

['Heigel, J.C.', 'Lane, B.M.']

2021-11-03T22:09:14Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89948

eng

2017 International Solid Freeform Fabrication Symposium

Open

['thermographic measurement', 'scan track', 'cooling rate', 'melt pool length', 'in-situ', 'powder bed fusion']

The Effect of Powder on Cooling Rate and Melt Pool Length Measurements Using In-Situ Thermographic Techniques

Conference paper

https://repositories.lib.utexas.edu//bitstreams/95a52c07-1d32-44ad-9075-7fe3df4e99b8/download

University of Texas at Austin

High-speed thermal cameras enable in situ measurement of the temperatures in and around melt pools generated during powder bed fusion processes. These measurements can be used to validate models, to monitor the process, and to understand the microstructure formed during the process. Unfortunately, pre-placed powder layers complicate the measurement due to spatter and irregular surfaces that impact emissivity. The objective of this work is to present high speed thermographic measurements of single and multiple scan tracks on substrates with and without pre-placed powder and to analyze and compare the impacts of powder on melt pool length and cooling rate measurements.

null

['Chen, Xueyang', 'Yan, Lei', 'Li, Wei', 'Liou, Frank', 'Newkirk, Joe']

2021-10-27T21:43:34Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89624

eng

2016 International Solid Freeform Fabrication Symposium

Open

['direct laser metal deposition', 'powder mixture', 'particle size', 'Ti-6Al-4V']

Effect of Powder Particle Size on the Fabrication of Ti-6Al-4V using Direct Laser Metal Deposition from Elemental Powder Mixture

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fdd8627d-fe9c-4586-bcc0-e17f7c5f92de/download

University of Texas at Austin

Direct Laser Metal Deposition (LMD) was used to fabricate thin-wall Ti-6Al-4V using the powder mixture of Ti-6 wt.%Al-4 wt.%V. Scanning electron microscopy (SEM), optical microscopy (OM) and energy dispersive spectroscopy (EDS) were employed to examine the chemical composition and microstructure of the as-deposited sections. Vickers hardness tests were then applied to characterize the mechanical properties of the deposit samples which were fabricated using pre-mixed elemental powders. The EDS line scans indicated that the chemical composition of the samples was homogenous across the deposit. X-ray diffraction (XRD) was used for the phase identification. After significant analysis, some differences were observed among two sets of deposit samples which varied in the particle size of the mixing Ti-6wt.%Al-4wt.%V powder. It could be found that the set with similar particle number for Ti, Al and V powder made composition much more stable and could easily get industry qualified Ti-6Al-4V components.

null

['Mahtabi, MohammadBagher', 'Yadollahi, Aref', 'Stokes, Ryan', 'Morgan-Barnes, Courtney', 'Young, Joseph', 'Doude, Haley', 'Bian, Linkan']

2023-01-26T14:12:44Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117302', 'http://dx.doi.org/10.26153/tsw/44183']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Powder recycling', 'Virgin powder', 'Powder flowability', 'Powder size distribution']

Effect of Powder Reuse on Microstructural and Fatigue Properties of Ti-6Al-4V Fabricated via Directed Energy Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c4b964bd-b7b5-425e-a881-18d765c562be/download

null

In metal additive manufacturing (AM) processes, due to the high cost of metal powder, it is common to reuse the collected powder from the build envelope for future builds. Powder reuse may adversely affect the powder characteristics, including the flowability, size distribution, chemical composition, resultant microstructural, and consequently, mechanical properties of the fabricated parts. This study aims to investigate the effect of powder reuse on the microstructural features and fatigue performance of Ti-6Al-4V specimens fabricated using a directed energy deposition (DED) process. Characteristics of reused powder particles, such as the size distribution and chemical composition, were evaluated and compared with that of virgin powder. Microstructural features and characteristics of the process-induced defects were examined using scanning electron microscopy and x-ray computed tomography, respectively. Fatigue performance of the specimens fabricated using reused powder was evaluated and compared to their control counterparts, fabricated using virgin powder.

null

['Mahtabi, MohammadBagher', 'Yadollahi, Aref', 'Stokes, Ryan', 'Morgan-Barnes, Courtney', 'Young, Joseph', 'Doude, Haley', 'Bian, Linkan']

2023-01-19T16:02:58Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117246', 'http://dx.doi.org/10.26153/tsw/44127']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Powder recycling', 'Virgin powder', 'Powder flowability', 'Powder size distribution']

Effect of Powder Reuse on Microstructural and Fatigue Properties of Ti-6Al-4V Fabricated via Directed Energy Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c9aef631-883c-481e-9ae3-1e39ee42754a/download

null

In metal additive manufacturing (AM) processes, due to the high cost of metal powder, it is common to reuse the collected powder from the build envelope for future builds. Powder reuse may adversely affect the powder characteristics, including the flowability, size distribution, chemical composition, resultant microstructural, and consequently, mechanical properties of the fabricated parts. This study aims to investigate the effect of powder reuse on the microstructural features and fatigue performance of Ti-6Al-4V specimens fabricated using a directed energy deposition (DED) process. Characteristics of reused powder particles, such as the size distribution and chemical composition, were evaluated and compared with that of virgin powder. Microstructural features and characteristics of the process-induced defects were examined using scanning electron microscopy and x-ray computed tomography, respectively. Fatigue performance of the specimens fabricated using reused powder was evaluated and compared to their control counterparts, fabricated using virgin powder.

null

['Nezhadfar, P.D.', 'Soltani-Tehrani, Arash', 'Shamsaei, Nima']

2021-11-17T23:54:01Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90360', 'http://dx.doi.org/10.26153/tsw/17281']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['laser beam powder bed fusion', 'LB-PBF', 'preheating', 'stainless steel', 'porosity', 'mechanical properties', 'microstructure']

Effect of Preheating Build Platform on Microstructure and Mechanical Properties of Additively Manufactured 316L Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/627329fa-e9c1-411e-b85b-f8d67c447fd9/download

University of Texas at Austin

This study aims to understand the effect of build platform preheating on the microstructural features and mechanical properties of 316L stainless steel (SS) fabricated via laser beam powder bed fusion (LB-PBF) process. Two sets of specimens were fabricated on a non-preheated build platform and the build platform preheated to 150 °C. Thermal simulations are carried out using ANSYS using additive manufacturing module to investigate the variation in thermal history experienced by the specimens in each condition. Microstructural features are analyzed via simulation, and the results are validated experimentally. In addition, the effect of preheating on the porosity size and distribution is evaluated using digital optical microscopy. Mechanical properties of specimens from each condition are further assessed and correlated to the variations in microstructure and defect size distributions.

null

['Myers, K.', 'Paterson, A.', 'Iizuka, T.', 'Klein, A.']

2021-11-16T15:59:44Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90324', 'http://dx.doi.org/10.26153/tsw/17245']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['print speed', 'surface roughness', 'density uniformity', 'binder jetting', 'binder jet 3D printing']

The Effect of Print Speed on Surface Roughness and Density Uniformity of Parts Produced Using Binder Jet 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4287838f-ef54-4cae-b8b5-f21c506c7864/download

University of Texas at Austin

One of the main benefits of binder jetting is the ability to print quickly compared to other metal additive manufacturing methods. Demand for higher throughput continues to increase, but the effects of faster print speeds on part outcomes are not yet clearly understood. MIM powders are used to achieve optimal density and surface finish. Printing at slower speeds results in densities near 98% and average surface roughness values as low as 4 μm (Ra), in the as-sintered condition. In this study, spread speeds were varied in order to understand the effect of print speed on surface roughness. 316L D90 -22 μm powder was used to print with 3 different spread speeds, 2 different layer thicknesses, and 2 different printhead droplet sizes. The surface finish and density were quantified for the sintered parts that were oriented at 0, 22.5, and 45 degrees with respect to the Z-direction.

null

['Moreno-Núñez, Benjamin A.', 'Trevino-Quintanilla, Cecilia D.', 'Esponiza-Garcia, Juan Carlos', 'Uribe-Lam, Esmeralda', 'Cuan-Urquizo, Enrique']

2024-03-27T03:55:34Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124478', 'https://doi.org/10.26153/tsw/51086']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'fused filament fabrication', 'statistical analysis', 'fractional fractorial design', 'internal geometry', 'thermoplastics']

Effect of Printing Parameters on the Internal Geometry of Products Manufactured by Fused Filament Fabrication (FFF)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8e98090f-4507-4ea4-823a-cb4b47bf1710/download

University of Texas at Austin

The internal geometry of a 3D-printed product determines its mechanical properties. In Fused Filament Fabrication (FFF) the filaments that build up the internal geometry suffer from variations that have not been sufficiently studied. This research focused on identifying the parameters that most affect the filaments and finding the optimum values to reduce their variations. A fractional factorial design of experiments was used to detect the printing parameters of FFF that most affect the width of extruded filaments, these results were also statistically analyzed. A response optimization was done to obtain the values of the printing parameters that will give the closest width of extruded filaments to the nozzle of the 3D printer used. Results showed layer height has the largest impact on filament width variation.

null

['Bauer, D.M.', 'Dietrich, K.', 'Walter, M.', 'Forêt, P.', 'Palm, F.', 'Witt, G.']

2021-10-26T19:27:34Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89564

eng

2016 International Solid Freeform Fabrication Symposium

Open

['process gas', 'oxygen levels', 'powder quality', 'aluminum alloys', 'laser based powder bed melting', 'powder bed']

Effect of Process Gas and Powder Quality on Aluminum Alloys Processed by Laser Based Powder Bed Melting Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/50f7c352-076c-407a-81e6-b01d6684f367/download

University of Texas at Austin

The production of parts and components by Additive Layer Manufacturing (ALM) offers potential cost benefits for aeronautic applications. Laser Based Powder Bed Melting Process offers design flexibility while enabling weight reduction due to topological optimization by substitute conventional design and manufacturing routes. Especially aluminum alloys are highly sensitive to oxygen and hydrogen impurity during the process. Due to this, it is mandatory to control precisely and hold a low oxygen level while processing. Hereby it is possible to avoid any negative impact on the final mechanical properties as tensile strength and fatigue resistance. For the investigations, aluminum powder (Al-Si-Mg) is used. This paper will present the influence of the oxygen level during processing on the final mechanical properties of the part. Even if pure Argon is commonly used to inert the chamber, different sources of oxygen like powder, equipment and gas supply have a negative impact and will be investigated. [1]–[4]

null

['Pegues, Jonathan', 'Leung, Kelvin', 'Keshtgar, Azadeh', 'Airoldi, Luca', 'Apetre, Nicole', 'Iyyer, Nagaraja', 'Shamsaei, Nima']

2021-11-02T13:43:33Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89800

eng

2017 International Solid Freeform Fabrication Symposium

Open

['mechanical properties', 'microstructure', 'additive manufacturing', 'ICME', 'titanium alloys']

Effect of Process Parameter Variation on Microstructure and Mechanical Properties of Additively Manufactured Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c30b2797-2968-4267-b82c-59fe027ab25b/download

University of Texas at Austin

As additively manufactured (AM) parts become viable options for various structural applications, it is essential to fully understand how various process parameters affect their subsequent mechanical behavior. In this study, a process simulation package is utilized to model the heat transfer during the laser-based powder bed fusion (L-PBF) process. Along with mechanical properties, the model is capable of estimating porosity, density, and microstructural evolution during the rapid cooling phases associated with L-PBF. Simulation results were validated using experimentally measured mechanical properties of L-PBF Ti-6Al-4V specimens. Tensile tests and microscopy were conducted for determining the effects of process parameters (i.e. laser power, laser scan speed, hatch distance) on microstructure, strength, and ductility of fabricated parts. Predictions from process simulations were compared with experimental results. Validated process simulation packages, used and developed herein, can provide a low-cost means for the quality control of AM parts.

null

['Dilip, J.J.S.', 'Stucker, Brent', 'Starr, Thomas L.']

2021-10-13T20:24:33Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88777', 'http://dx.doi.org/10.26153/tsw/15711']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['HY100 steel', 'selective laser mleting', 'process parameters', 'tempering treatment', 'temper heat treatment']

Effect of Process Parameters and Heat Treatment on the Microstructure and Mechanical Properties of SLM-built HY100 Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6b8c89cb-bac2-4dab-90bd-ee214ff9e7d2/download

University of Texas at Austin

HY100 is a high strength low alloy steel used for naval and pressure vessel applications. In general, the alloy is used in the quenched and tempered condition. In the present work, fully dense metallic samples were produced from HY100 pre-alloyed powders using selective laser melting (SLM). Test samples were built with varying process parameters (scan speed and laser power). The SLM-built samples were given direct tempering treatment and a standard quench and temper heat treatment. Tensile properties of the samples were evaluated in direct temper, and quench and temper conditions. The study investigates the influence of process parameters and heat treatment on the microstructure and mechanical properties of SLM-built HY100 steel.

null

['Izadi, Mojtaba', 'Farzaneh, Aidin', 'Gibson, Ian', 'Rolfe, Bernard']

2021-11-03T20:44:28Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89928

eng

2017 International Solid Freeform Fabrication Symposium

Open

['stainless steel 316', 'process parameters', 'macrostructure', 'mechanical properties', 'direct energy deposition']

The Effect of Process Parameters and Mechanical Properties of Direct Energy Deposited Stainless Steel 316

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ee88a340-0fcc-4191-9c87-d5968f7e7408/download

University of Texas at Austin

Process parameters in Direct Energy Deposition (DED) Additive Manufacturing are playing an important role in order to fabricate desired parts. In this research, we studied the effect of 3 process parameters, namely laser power, scan speed and powder feed rate. Based on variation of these parameters, we examined macrostructure and mechanical properties of stainless steel 316 fabricated parts, employing an orthogonal L9 array using the Taguchi technique. The results showed laser power to be the most effective factor whereas scan speed and powder feed rate were respectively less effective. In addition, effect of height of deposition was also considered. The results indicated change in macrostructure with increasing height. Finally, validation of a previously defined energy density equation for the DED process was studied. The results clearly showed the current energy density equation cannot fully represent a relation between input energy and output geometry, macrostructure, and mechanical properties.

null

['Kanger, Cody', 'Hadidi, Haitham', 'Akula, Sneha', 'Sandman, Chandler', 'Quint, Jacob', 'Alsunni, Mahdi', 'Underwood, Ryan', 'Slafter, Cody', 'Sonderup, Jason', 'Spilnek, Mason', 'Casias, John', 'Rao, P.', 'Sealy, M.P.']

2021-11-02T18:00:29Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89840

eng

2017 International Solid Freeform Fabrication Symposium

Open

['fused filament fabrication', 'shot peening', 'ABS', 'strength', 'elongation']

Effect of Process Parameters and Shot Peening on Mechanical Behavior of ABS Parts Manufactured by Fused Filament Fabrication (FFF)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4b3ca70e-79aa-4ff2-a083-1cb4828a15b3/download

University of Texas at Austin

The goal of this research was to understand how shot peening affected the tensile strength and elongation of ABS polymer parts between three process parameters: layer height, infill angle, and outer shell quantity. Experiments were conducted using a Hyrel 30M fused filament fabrication (FFF) printer to produce ASTM 638D-IV samples. This is an important area of research because 3D printed polymers have typically been limited to prototyping applications due to low strengths and stiffness. Traditional means of improving a polymer’s mechanical properties are changing the structural or chemical makeup. However, shot peening, a surface treatment commonly used to improve mechanical properties of metals, was hypothesized to have a statistically significant effect on the tensile strength and elongation of polymer parts. Results showed that shot peening had a significant effect on decreasing the tensile strength. Although not statistically significant, samples did show an increase in elongation after shot peening.

null

['Madireddy, G.', 'Montazeri, M.', 'Curtis, E.', 'Berger, J.', 'Underwood, N.', 'Khayari, Y.', 'Marth, B.', 'Smith, B.', 'Christy, S.', 'Krueger, K.', 'Sealy, M.P.', 'Rao, P.']

2021-11-04T15:04:00Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/89980', 'http://dx.doi.org/10.26153/tsw/16901']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['stereolithography', 'shot peening', 'polymer', 'strength', 'deflection']

Effect of Process Parameters and Shot Peening on the Tensile Strength and Deflection of Polymer Parts Made Using Mask Image Projection Stereolithography (MIP-SLA)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/24ca5417-24e1-4339-82dd-02c0189e9d99/download

University of Texas at Austin

Mask Image Projection Stereolithography (MIP-SLA) is an additive manufacturing technique in which a liquid photopolymer resin is hardened from exposure to ultraviolet (UV) light. Shot peening is a surface treatment to improve the mechanical properties of components. The goal of this work was to quantify the effect of SLA print process parameters, namely layer height and UV exposure, and shot peening on the longitudinal tensile strength of ASTM D638 Type 5 test artifacts. Test parts were created using a central composite experimental plan on a B9 Creator desktop SLA machine. Deflection of the pseudo-Almen strips after shot peening was measured using a digital camera to identify desired peening condition. Post-shot peening tensile strength was measured for the ASTM D638 Type 5 parts. Shot peening generally decreased the strength of MIPSLA parts.

null

['Liao, Hailong', 'Zhu, Haihong', 'Zhu, Junjie', 'Chang, Shijie', 'Zeng, Xiaoyun']

2021-11-18T02:14:40Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90410', 'http://dx.doi.org/10.26153/tsw/17331']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['process parameters', 'relative density', 'loss rate', 'loss mechanism', 'Al2O3', 'Al2O3-Al cermet', 'selective laser melting']

Effect of Process Parameters on Selective Laser Melting Al2O3-Al Cermet Material

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6e753ae1-8e5f-4dcd-ae17-a37101488a2e/download

University of Texas at Austin

The cermet composite material is one of the researches focuses in the field of materials, for it can combine the toughness of metal and the hardness of ceramics. In this work, Al2O3-Al cermet composite with a mass ratio of 1:1 was fabricated by selective laser melting process. The effect of process parameters on the relative density and Al2O3 loss rate, as well as the Al2O3 loss mechanism, was investigated in detail. The results show that Al2O3 undergoes melt recrystallization and is significantly aggregated. The aggregated Al2O3 exhibits a network distribution in the metal matrix. The process parameters have a great influence on the relative density and the Al2O3 loss rate. As the scanning speed decreases, the relative density and the Al2O3 loss rate are changed with a contrary tendency. The loss mechanism is that the aluminum acts as a reducing agent, causing the Al2O3 becoming a gaseous substance Al2O during selective laser melting process.

null

['Xue, Fangkai', 'Robin, Guillaume', 'Boudaoud, Hakim', 'Cruz Sanchez, Fabio A.', 'Daya, El Mostafa']

2021-12-01T23:25:15Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90654', 'http://dx.doi.org/10.26153/tsw/17573']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['vibration properties', 'fused filament fabrication', 'FFF', 'modal analysis', 'poylactic acid', 'PLA', 'design of experiments', 'DoE']

Effect of Process Parameters on the Vibration Properties of PLA Structure Fabricated by Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/920520b7-c8ac-4f0e-b084-cd7ec4227e98/download

University of Texas at Austin

Advances in Fused Filament Fabrication (FFF) enable the design and manufacturing of multi-material and multi-functional structure that can potentially be used to develop light weight and high damping structures for vibration control. However, very few studies mention the vibration characteristics of FFF printed structures. This paper investigates the effect of four process parameters, raster angle, nozzle temperature, layer height and deposition speed, on the vibration properties of FFF printed Polylactic Acid (PLA) structure through modal analysis and design of experiment. The effects of all four parameters show a good agreement on the first fives modes of resonance. It was found that raster angle significantly affects both resonance frequency (16.6%) and loss factor (7.5%). Meanwhile, the impact of the other three parameters is relatively low (less than 4%), which is different from previous research results on static mechanical properties. All these results provide a guidance for further application of FFF in vibration field.

null

['Nie, Xiaojia', 'Zhang, Hu', 'Zhu, Haihong', 'Hu, Zhiheng', 'Zeng, Xiaoyan']

2021-11-10T22:57:15Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90201', 'http://dx.doi.org/10.26153/tsw/17122']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['processing parameter', 'zirconium modified', 'Al-Cu-Mg alloys', 'selective laser melting']

The Effect of Processing Parameter on Zirconium Modified Al-Cu-Mg Alloys Fabricated by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/290b3450-f0b9-4ae7-9e75-fc412635ea55/download

University of Texas at Austin

The newly designed alloy compositions for selective laser melting (SLM) have aroused great interest. In this study, zirconium modified Al-Cu-Mg alloys were fabricated by SLM. Results show that crack-free samples with relative density of nearly 100% were obtained by optimizing the processing parameters. With the increase of scanning speed, the relative density decreases due to insufficient energy input. In addition, the microstructure transforms from homogeneous to bio-modal, the reason is the unstable flows caused by the high scanning speed. The small hatching space will provide more energy input and preheat, leading to the coarse surface.

null

['Badrinarayan, B.', 'Barlow, J.W.']

2018-10-04T19:32:59Z

1995

Mechanical Engineering

doi:10.15781/T28W38M8W

http://hdl.handle.net/2152/68706

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SLS', 'laser processing', 'CAD']

Effect of Processing Parameters In SLS Of Metal-Polymer Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5df7e1c7-c167-4fb0-8fe6-cce5a913378d/download

null

This paper describes the effect of processing parameters in SLS of metal-polymer powder mixtures. Test bars for measurement of strength and density were made from copper-PMMA powder mixtures using SLS. The effect of Energy Density during laser processing, effect of vector length, bed temperature, polymer melt index and initial binder content on part strength and density are discussed in this paper. The green part strengths and densities were found to increase with Energy Density upto a value of 6.0 caVcm2 and then they drop off due to polymer degradation. Parts made with lower vector lengths yielded higher strengths and densities than those with higher vector lengths. Parts processed with a low melt index polymer binder (around 6.0 gmllOmin) showed higher strengths than parts processed with higher melt index binders. High strength values were obtained for green parts made from powders that had a greater initial binder content. Bed temperature did not have a very significant effect on part strength and densities.

null

['Olakanmi, E. O.', 'Cochrane, R. F.', 'Dalgarno, K. W.']

2020-03-09T15:20:20Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80196', 'http://dx.doi.org/10.26153/tsw/7215']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Densification

Effect of Processing Parameters on the Density and Microstructure of Direct Laser Sintered Al-12Si Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/84136423-1739-4091-ad9f-aa12b5d0b48e/download

null

The effect of processing parameters on the sintering behaviour of gas atomised Al-12Si powders has been investigated. Laser power, scanning rate, scan spacing and layer thickness are found to control the densification and the resultant microstructural characteristics of the laser sintered parts. It was found that sintered density increased as the energy density increased reaching a maximum of 80.2% at an energy input per unit volume of 67 J mm-3. For parts produced with a slightly lower power density (50 J mm-3), the microstructure consisted of fine dendrites with interconnected porosity while parts fabricated with a slightly higher power density (100 J mm-3) were noted to have a preponderance of coarse dendrites with a discontinuous network of irregular shaped pores surrounded by a fully dense aluminium-silicon matrix.

null

['Ge, Wenjun', 'Lin, Feng', 'Guo, Chao']

2021-10-13T19:27:18Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88768', 'http://dx.doi.org/10.26153/tsw/15702']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['electron beam selective melting', 'Ti47Al2Cr2Nb', 'scan patterns', 'microstructure evolution', 'Ultimate Tensile Strength']

The Effect of Scan Pattern on Microstructure Evolution and Mechanical Properties in Electron Beam Melting Ti47Al2Cr2Nb

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1ff1c6d4-8e64-4a6c-a9f3-b2be8ccd272c/download

University of Texas at Austin

Ti47Al2Cr2Nb alloy square samples with dimensions of 20mm x 20mm x 5mm were fabricated by electron beam selective melting. In order to study the effect of electron beam scan pattern on the microstructure evolution, three different scan patterns were employed: S-shaped scan line, Z-shaped scan line and interlayer orthogonal S-shaped scan line. Microstructural and chemical analyses were conducted using optical microscopy, scanning electron microscopy and energy differential system. It is worth noting that the element Al loss rate was about 8% under different process parameters. As a result, the microstructures of EBSM Ti47Al2Cr2Nb samples were composed of columnar β grains, α/α2and α2/γ lamellar. Tensile tests were carried out to understand the mechanical properties to the corresponding microstructures. Ultimate Tensile Stress (UTS)at room temperature is much lower than that at a high temperature.

null

['Anam, Md Ashabul', 'Dilip, JJS', 'Pal, Deepankar', 'Stucker, Brent']

2021-10-12T22:37:31Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88758', 'http://dx.doi.org/10.26153/tsw/15692']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'Inconel 625', 'scan patterns', 'microstructure', 'Nb grains', 'Mo grains']

Effect of Scan Pattern on the Microstructural Evolution of Inconel 625 during Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/64cccc2e-f959-41ee-9b2b-f96b2fca48c3/download

University of Texas at Austin

Selective laser melting (SLM) involves highly localized heat input and directional solidification, which enables novel microstructure control through the development of scanning strategies and related process variables. A careful study of scan pattern is important to understand microstructural evolution during SLM. In this study, various types of scanning strategies were used to build samples of Inconel 625. Microstructure differences due to different scan patterns in as-built Inconel 625 samples were then studied in detail. Microstructure samples showed grains with cellular substructure with enriched regions of Nb and Mo in the inter arm spacing. The grains were observed to grow preferentially in the build direction, but there were also clear effects of grain orientation differences due to scan direction effects.

null

['AlMangour, B.', 'Grzesiak, D.', 'Yang, J.M.']

2021-10-26T20:26:41Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89578

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'porosity', 'microstructure', 'hardness']

Effect of Scanning Methods in the Selective Laser Melting of 316L/TiC Nanocomposites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/68c69b88-6708-4bc7-917a-acc4b5b5af31/download

University of Texas at Austin

Selective laser melting (SLM) is a promising additive manufacturing process that allows for the fabrication of complex functional components by the selective layer-by-layer melting of particles on a powder bed using a high-energy laser beam. In this study, the SLM process was used to fabricate components of TiC/ 316L stainless steel nanocomposite using various laser scanning methods. The results showed that the laser-scanning method used for the SLM process affects the degree of densification, microstructure, and the hardness of the components produced. We believe that the alternative fabrication route presented in this study should significantly increase the use of nanocomposites.

null

['Niu, F.Y.', 'Wu, D.J.', 'Ma, G.Y.', 'Zhou, S.Y.', 'Zhang, B.']

2021-10-13T19:59:18Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88773', 'http://dx.doi.org/10.26153/tsw/15707']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['second-phase doping', 'Al2O3 ceramics', 'laser deposition', 'additive manufacturing', 'laser engineering net shaping']

Effect of Second-Phase Doping on Laser Deposited Al2O3 Ceramics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7dd4673e-f758-40f0-8cf0-664f8269ce39/download

University of Texas at Austin

Direct fabrication of engineering ceramic components by additive manufacturing (AM) is a relatively new method for producing complex mechanical structures. This study investigates how a second-phase doping may affect Al2O3 ceramic parts deposited by AM with a laser engineered net shaping (LENS) system. In this study, ZrO2 and Y2O3 powders are respectively doped into Al2O3 powders at the eutectic ratio as second-phases to improve the quality of a deposited part. The deposited Al2O3, Al2O3/ZrO2 and Al2O3/YAG (yttrium aluminum garnet) parts are examined for their micro-structures and micro-hardness, as well as defects. The results show that doping of ZrO2 or Y2O3 as a second-phase performs a significant role in suppressing cracks and in refining grains of the laser deposited parts. The micro-hardness investigation reveals that the second-phase doping does not result in much hardness reduction in Al2O3 and the two eutectic ceramics are both harder than 1500 Hv. The study concludes that the second-phase doping is good for improving laser deposited ceramic parts.

null

['Majewski, C.E.', 'Hopkinson, N.']

2021-09-30T15:46:40Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88268', 'http://dx.doi.org/10.26153/tsw/15209']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['section thickness', 'Laser Sintered parts', 'mechanical properties', 'tensile properties', 'Fracture Toughness', 'Additive Manufacturing']

Effect of Section Thickness and Build Orientation on Tensile Properties and Material Characteristics of Laser Sintered Nylon-12 Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a0fb70fb-0cb2-4499-9ca1-11a049b0a595/download

University of Texas at Austin

It has been suggested that different section thicknesses in Laser Sintered parts may cause variations in mechanical properties, and this has previously been demonstrated for some properties (e.g. fracture toughness). The research presented here investigates whether the same is true of tensile properties, and whether the orientation of parts within the build volume has any effect on this. Results are presented for three different orientations of tensile specimens, at a range of thicknesses from 2mm to 6mm, showing that, at any of the orientations tested, the section thickness had no significant effect on any of the main tensile properties. These results are in direct contradiction with related research investigating the effect of section thickness on Fracture Toughness, where an increase in thickness also increased the toughness of the parts. This highlights the importance to Additive Manufacturing users of identifying the correct properties to assess when choosing a suitable process or material, and when designing complex parts.

null

['Fulcher, Ben', 'Leigh, David K.']

2021-10-06T20:33:27Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88436', 'http://dx.doi.org/10.26153/tsw/15373']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'Melt Flow Index', 'Differential Scanning Calorimetry', 'polymer parts']

Effect of Segregated First and Second Melt Point on Laser Sintered Part Quality and Processing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2feea4d1-ee71-479b-a362-90a221c8ed28/download

University of Texas at Austin

Efforts to tailor laser sintering polymers to enhance part quality, performance, and processing have relied on the characterization of the polymers using Melt Flow Index (MFI) and Differential Scanning Calorimetry (DSC). Two grades of laser sintering nylon polyamide are compared and the resultant processing window, part quality, and mechanical behavior are discussed. A better understanding of characterization techniques and the processing of laser sintered polymers is leading to engineering thermoplastics for exclusive use in additive manufacturing.

null

['Hoskins, Dylan', 'Ajinjeru, Christine', 'Kunc, Vlastimil', 'Lindahl, John', 'Nieto, Daniel Moreno', 'Duty, Chad']

2021-11-10T21:54:06Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90189', 'http://dx.doi.org/10.26153/tsw/17110']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['shear strain', 'extrusion viscosity', 'fiber reinforced polymers', 'acrylonitrile butadiene styrene', 'ABS', '3D printing', 'big area additive manufacturing', 'BAAM']

The Effect of Shear-Induced Fiber Alignment on Viscosity for 3D Printing of Reinforced Polymers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/db9eaddd-b3c6-4727-854a-a16f42e36d17/download

University of Texas at Austin

Material printed with large scale additive manufacturing systems such as the Big Area Additive Manufacturing (BAAM) system experience a wide range of shear rates during the extrusion process. The shear rate can vary over five orders of magnitude as the material passes through the single screw extruder and is deposited onto previous layers. When fiber reinforced materials are deposited, the fibers can become highly aligned in the direction of flow due to the high shear stresses experienced as the material passes through the nozzle. Therefore, accurate analysis of the viscoelastic response of a polymer during extrusion should replicate these conditions as closely as possible. This study evaluates the effect of a pre-conditioning shear strain on the extrusion viscosity of carbon fiber reinforced acrylonitrile butadiene styrene (ABS).

null

['Montgomery, Colt', 'Farnin, Christopher', 'Mellos, Greg', 'Brand, Michael', 'Pacheco, Robin', 'Carpenter, John']

2021-11-09T18:35:34Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90112', 'http://dx.doi.org/10.26153/tsw/17033']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['surface finish', 'shield gas', 'metal powder', 'laser powder bed fusion', 'L-PBF']

Effect of Shield Gas on Surface Finish of Laser Powder Bed Produced Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2cd3bd39-eb04-465b-b4fe-76fb315bb712/download

University of Texas at Austin

Additive manufacturing (AM) of metals is a novel manufacturing technique that allows for net-shape or near net-shape parts to be produced quickly. Within additive manufacturing a large concern is the produced surface finish, especially for upward and downward facing surfaces on complex geometries. Surface finish is of utmost importance for many engineering applications. In melting of powders, the gas used dominates the thermal conductivity of the metal powder. Manipulation of the type of shield gas may provide a means to modify the surface finish without adjustment of established lasing parameters and thereby produce a higher quality part with minimal post processing. These results have potential applications in aerospace, automotive, and biomedical sectors where surface finish requirements coupled with complex geometries are extremely common.

null

['Engeli, R.', 'Etter, T.', 'Geiger, F.', 'Stankowski, A.', 'Wegener, K.']

2021-10-20T22:46:53Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89381

eng

2015 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'IN738LC', 'gas turbine', 'silicon', 'hot cracking']

Effect of Si on the SLM Processability of IN738LC

Conference paper

https://repositories.lib.utexas.edu//bitstreams/263116e2-82ca-4a40-bf5e-ab7a4cd34169/download

University of Texas at Austin

Selective laser melting of high gamma-prime strengthened superalloys such as IN738LC is of interest in stationary gas turbine applications. Differences have been obtained for the hot cracking susceptibility of different powder batches during SLM processing and indications were found that also minor elements influence the SLM processability. By processing a specific powder batch blended by different amounts of pure silicon, the detrimental effect of this element during SLM could be shown. Therefore, the control of this minor element is crucial to decrease the hot cracking tendency and can extend the SLM processing window of this alloy.

null

['Norazman, Farhana', 'Hopkinson, Neil']

2021-10-07T18:53:19Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88504', 'http://dx.doi.org/10.26153/tsw/15438']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['high speed sintering', 'thermoplastic elastomer', 'tensile properties', 'sintering power', 'flow agent']

Effect of Sintering Parameters and Flow Agent on the Mechanical Properties of High Speed Sintered Elastomer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6fe3450d-f2ac-4883-a284-da8a39fea5b4/download

University of Texas at Austin

High Speed Sintering (HSS) is an Additive Manufacturing process that creates parts by sintering using inkjet and infra-red lamp technology rather than laser systems employed in Laser Sintering (LS). This research investigated the effects of machine parameters (sintering power, bed temperature) and the addition of fumed silica flow agent on the tensile properties of thermoplastic elastomer parts processed using HSS. The results showed improved elongation at break values by a factor of more than 2X compared to reported values for LS of the same thermoplastic elastomers. At constant parameters, improved tensile strength and tensile modulus were observed with the addition of flow agent into the sintering mixture.

null

['Meng, S.', 'Mason, L.', 'Taylor, G.', 'Wang, X.', 'Leu, M.C.', 'Chandrashekhara, K.']

2021-11-01T22:17:18Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89778

eng

2016 International Solid Freeform Fabrication Symposium

Open

['sparse-build tool', 'pressure', 'topology optimization', 'Ultem 9085', 'fused deposition modeling']

Effect of Sparse-Build Internal Structure on Performance of Fused Deposition Modeling Tools Under Pressure

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0a27c4ea-f7ab-44be-bd09-22f087bc6859/download

University of Texas at Austin

Two different approaches to design a sparse-build tool for fabrication by the fused deposition modeling (FDM) process are compared. One approach uses a 2D lattice structure and the other approach is inspired by topology optimization. Ultem 9085 is used as the material, and the amount of material used to build the tool is kept constant to ensure a fair comparison. A solid tool is also included in the comparison. The performance of the tool under uniform pressure is simulated using finite element analysis (FEA) and the accuracy of the FEA results is verified by comparing them with experimentally measured data for a similar tool. The build material, support material, build time, maximum displacement, and maximum von Mises stress are compared for the three build approaches, with an emphasis on the pros and cons of each sparse-build tool with regards to performance under uniform pressure and fabrication by FDM.

null

['Pegues, Jonathan', 'Roach, Michael', 'Williamson, R. Scott', 'Shamsaei, Nima']

2021-11-02T14:00:22Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89805

eng

2017 International Solid Freeform Fabrication Symposium

Open

['fatigue', 'additive manufacturing', 'surface effects', 'microstructure', 'titanium alloys']

Effect of Specimen Surface Area Size on Fatigue Strength of Additively Manufactured Ti-6Al-4V Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/80824146-cb62-46dd-abb1-771da55a277a/download

University of Texas at Austin

As additive manufacturing becomes an increasingly popular method for advanced manufacturing of components, there are many questions that need to be answered before these parts can be implemented for structural purposes. One of the most common concerns with additively manufactured parts is the reliability when subjected to cyclic loadings which has been shown to be highly sensitive to defects such as pores and lack of fusion between layers. It stands to reason that larger parts will inherently have more defects than smaller parts which may result in some sensitivity to surface area differences between these parts. In this research, Ti-6Al-4V specimens with various sizes were produced via a laser-based powder bed fusion method. Uniaxial fatigue tests based on ASTM standards were conducted to generate fatigue-life curves for comparison. Fractography on the fractured specimens was performed to distinguish failure mechanisms between specimen sets with different sizes.

null

['Lu, Bing', 'Li, Mingyang', 'Lao, Wenxin', 'Weng, Yiwei', 'Qian, Shunzhi', 'Tan, Ming Jen', 'Leong, Kah Fai']

2021-11-15T21:21:27Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90277', 'http://dx.doi.org/10.26153/tsw/17198']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', '3D cementitious material printing', 'spray', 'material distribution', 'modelling']

Effect of Spray-Based Printing Parameters on Cementitious Material Distribution

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ccd75d24-8487-4f30-8664-7641b59b8150/download

University of Texas at Austin

In the past decade, 3D printing is getting into more and more industry areas including building and construction. However, most 3D cementitious material printing processes are limited in horizontal printing surface. Due to the nature of building and construction industry, 3D spray cementitious material printing process was developed to apply material in vertical or even overhang surfaces. Unlike traditional manually operated spray method in building and construction industry, 3D spray cementitious material printing process requires higher accuracy on material distribution. In this paper, the effects of four printing parameters (cementitious material flow rate, air flow rate, nozzle travel speed, nozzle standoff distance) on material distribution in 3D spray cementitious material printing process were investigated experimentally. An experimental model, which can be further used in the control of 3D spray cementitious material printing process, was then developed upon on the results.

null

['El Fazani, H.H.', 'Coil, J.D.A.', 'Shah, R.R.', 'Laliberte, J.F.']

2021-12-01T23:43:47Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90661', 'http://dx.doi.org/10.26153/tsw/17580']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'fused deposition modelling', 'fatigue crack', 'fatigue coupons', 'stress intensity factor']

The Effect of Stress Intensity Factor on Fatigue Life of AM Parts Made from Polymer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/abffc11b-3bfc-4698-8de3-a95dbde79848/download

University of Texas at Austin

The fatigue characteristics of additively manufactured specimens was investigated. A commercial acrylonitrile-butadiene-styrene (ABS) polymer (P430) was selected to manufacture AM fatigue coupons due to its low cost and wide applications. A total of 30 fatigue coupons were built on flat and on edge using a Stratasys SST 1200es fused deposition machine. The AM samples were manufactured at different build orientations of 0°, 22.5°, 45°, 67.5°, and 90°. The objective of this experiment is to investigate the influence of stress intensity factor on fatigue life of AM polymer parts. The specimens were tested under low sinusoidal tension-tension fatigue loading. The fatigue crack behaviour was monitored using a travelling microscope method. The stress intensity factor was investigated as the cycles accumulated. The effect of stress intensity factor on fatigue life was examined. The investigation of fatigue crack growth as a function of the number of fatigue cycles was discussed. It was found the fatigue coupons manufactured at 0° build orientation have a better fatigue life compared with the other build orientations. More investigation is required for other AM parameters such as layer thickness, infill density, manufacturing process to help better understand the fatigue performance of AM part made by polymer material. The Scanning Electron Microscope (SEM) technology was used to characterize the fractured surfaces and void distribution of AM fatigue parts. The void percentage was estimated. The results showed that AM fatigue parts built on flat has a higher void percentage compared to the AM parts manufactured on edge.

null

['Sparks, Todd', 'Ruan, Jianzhong', 'Fan, Zhiqiang', 'Bao, Yaxin', 'Liou, Frank']

2020-02-28T16:18:03Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80114', 'http://dx.doi.org/10.26153/tsw/7135']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Laser Aided Manufacturing Process

Effect of Structured Laser Pulses on Grain Growth in H13 Tool Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/92afa2e7-eb4b-41f0-a84e-cf3b7b27afcd/download

null

['Joseph, Shine', 'Quiñones, Stella', 'Medina, Frank', 'Wicker, Ryan']

2020-03-10T14:13:08Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80206', 'http://dx.doi.org/10.26153/tsw/7225']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Stereolithography

Effect of Surface Preparation Methods on Mechanical Properties of 3D Structures Fabricated by Stereolithography and 3D Printing for Electroless Ni Plating

Conference paper

https://repositories.lib.utexas.edu//bitstreams/03b7ad0c-81ab-40e3-bd50-6e67467ba9e8/download

null

Stereolithography (SL) and 3D Printing (3DP) are useful technologies for three-dimensional prototyping applications, providing highly accurate and detailed part geometries with high quality surface finishes. It is desired to improve the materials performance of the existing photocurable SL and 3DP resins for rapid tooling and other functional applications by applying a nickel (Ni) coating. In this work, surface preparation methods for electroless plating of commercial photopolymer resins such as NanoFormTM15120 (NanoForm) and Objet FullCure®840 (Veroblue) were explored in order to enhance the structural integrity of RP components. This study examined different surface preparation methods (chemical etching) and their effect on the surface morphology and mechanical strength of the polymers. It was observed that surface preparation of the resins significantly affected the mechanical properties and Ni plating of the substrate polymers. This is a critical step, since the Ni film takes on the surface structure of the substrate.

null

['Ordnung, D.', 'Metelkova, J.', 'Van Hooreweder, B.']

2024-03-25T23:41:42Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124341', 'https://doi.org/10.26153/tsw/50949']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'surface quality', 'surface state', 'additive manufacturing']

Effect of surface state and material on surface quality enhancement by Dual Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bf58b450-1138-47cc-a267-36d95f2544d1/download

University of Texas at Austin

Parts produced by Laser Powder Bed Fusion typically exhibit a limited surface quality often requiring systematic post-processing. The KU Leuven AM team recently developed a Dual Laser Powder Bed Fusion strategy to improve the quality of inclined up-facing surfaces during building. It consists of two steps: (1) a pulsed laser induces shock waves to remove powder from inclined surfaces, followed by (2) in-situ laser remelting of the newly exposed surfaces. The first part of this paper covers the powder removal efficiency using shock waves depending on the used material. A design of experiments was performed for horizontal samples of tool steels, titanium and aluminium alloys. The second part deals with the effect of the initial surface state on the powder removal efficiency for inclined surfaces (SaR,LT60=16.2 µm, SaR,LT120=24.0 µm). Finally, the third part demonstrates the surface quality improvement, resulting in a reduction of Ra up to 61% for 15° inclinations.

null

['Taminger, Karen M. B.', 'Hafley, Robert A.', 'Fahringer, David T.', 'Martin, Richard E.']

2020-02-14T15:47:59Z

8/4/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79987', 'http://dx.doi.org/10.26153/tsw/7012']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Electron beam freeform fabrication

Effect of Surface Treatments on Electron Beam Freeform Fabricated Aluminum Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d22ce4d8-9f49-4e44-bafa-d15e6ccef846/download

null

Electron beam freeform fabrication (EBF3) parts exhibit a ridged surface finish typical of many layer-additive processes. Thus, post-processing is required to produce a net shape with a smooth surface finish. High speed milling, wire electrical discharge machining (EDM), electron beam glazing, and glass bead blasting were performed on EBF3-built 2219 aluminum alloy parts to reduce or eliminate the ridged surface features. Surface roughness, surface residual stress state, and microstructural characteristics were examined for each of the different surface treatments to assess the quality and effect of the surface treatments on the underlying material. The analysis evaluated the effectiveness of the different surface finishing techniques for achieving a smooth surface finish on an electron beam freeform fabricated part.

null

['Sayah, Neshat', 'Smith, Douglas E.']

2024-03-25T22:36:42Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124325', 'https://doi.org/10.26153/tsw/50933']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['SCF/ABS', 'carbon', 'LAAM', 'additive manufacturing']

Effect of the Print Bed Temperature on Void Distribution within the Microstructure of Short Carbon Fiber Reinforced/ABS Manufactured via Large Area Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e62fa1b4-7046-4e6a-817d-f13dec00cd53/download

University of Texas at Austin

Short carbon fiber-reinforced polymer composite structures produced using Large Area Additive Manufacturing (LAAM) have garnered significant attention due to the design flexibility, energy savings, and materials selection associated with this process. However, the physical and mechanical properties of the additively manufactured composite parts often fall below expectations due to void formation between printed beads and within the microstructure of individual beads. This study aims to investigate the effect of bed temperature on the microstructure within the beads of two-layer Short Carbon Fiber reinforced Acrylonitrile Butadiene Styrene (SCF/ABS) beads manufactured via the LAAM system. This study employs high-resolution 3D micro-computed tomography (µCT) to evaluate the void shape and distribution within the microstructure of composite parts printed at various bed temperatures. The results of this study demonstrate substantial variation in the void volume fraction among four bead sets deposited at different print bed temperatures. Moreover, within each part, a noticeable discrepancy in void volume fraction is observed between the top and bottom bead of the two-bead test samples. Preliminary results indicate that increasing the bed temperature from 25°C to 75°C reduces void volume fraction within the microstructure of the composite parts. However, an opposite trend emerges when the bed temperature is further increased to 100°C, increasing void volume fraction, which needs further investigation to understand. This study also evaluated the void shapes through the calculation of their sphericity. The preliminary results reveal that as the bed temperature increases from 25°C to 75°C, the voids exhibit higher sphericity within the printed parts as the interconnected voids decrease.

null

['Nabil, S. T.', 'Arrieta, E.', 'Wicker, R. B.', 'Benedict, M.', 'Medina, F.']

2023-03-29T16:33:59Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117683', 'http://dx.doi.org/10.26153/tsw/44562']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser Powder Bed Fusion(L-PBF)', 'Fatigue Life', 'Thermal Aging', 'AlSi10Mg', 'Hot-Isostatic Pressing']

Effect of Thermal Aging in the Fatigue Life of Hot Isostatic Pressed AlSi10Mg Fabricated by Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2567daf0-96b1-467e-b429-7a62b62a7373/download

null

AlSi10Mg is a widely used material in the aerospace industry. Extended exposure to elevated temperatures can have a detrimental effect on it. In this work, multiple AlSi10Mg horizontal bars and vertical rods were fabricated using an L-PBF system. Following ASTM F3318-18, the material blanks were HIPed (Hot Isostatic Pressed). Emulating service temperatures, these blanks were aged at 177°C for 10, 100, and 1000h. Fatigue test specimens were machined down from the aged blanks. The machined specimens were subjected to a force-controlled fatigue test as per ASTM E466-15 with two stress levels: one within the elastic range (62MPa) of the material and another close to UTS (124MPa). The results indicated that even aging for 10h can dramatically reduce the fatigue life of the alloy. The work concludes with discussion on the reduction of fatigue life and visible progressive change in the ductility of the alloy with respect to the aging time.

null

['Khan, Md Faysal', 'Baig, Shaharyar', 'Ghiaasiaan, Seyed R', 'Gradl, Paul R', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-23T13:51:23Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117277', 'http://dx.doi.org/10.26153/tsw/44158']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser powder bed fusion (L-PBF)', 'AlSi10Mg', 'Scalmalloy', 'Hot isostatic pressing (HIP)', 'Microstructure', 'Tensile properties']

Effect of thermal post-processing on microstructure and tensile behavior of additively manufactured aluminum alloys (AlSi10Mg and Scalmalloy) via L-PBF: A comparative study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b7c33099-07be-4516-9248-851913d1c73e/download

null

Additively manufactured aluminum (Al) alloys have recently received growing interest from different industrial sectors. This study compares the microstructure and tensile properties of two laser powder bed fused Al alloys, namely AlSi10Mg and Scalmalloy, in different heat-treated (HT) conditions i.e., stress-relief, T6, and hot isostatic pressing (HIP), as well as the non-heat- treated condition. The microstructures were examined using scanning electron microscope, and the mechanical properties were evaluated using uniaxial tensile testing. For AlSi10Mg, Si- networks were observed to break down, and Si- and Fe-rich particles precipitates form during HIP followed by T6. For Scalmalloy, the density of nanometer-sized intergranular Al3(ScxZr1-x) precipitates increased after only HIP. Furthermore, it was observed that the addition of HIP improved the tensile strengths of both alloys as compared to their AM as well as wrought counterparts in similar HT conditions.

null

['Jandric, Z.', 'Ouyang, J.H.', 'Kovacevic, R.']

2019-10-24T17:32:16Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77402', 'http://dx.doi.org/10.26153/tsw/4491']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Welding

Effect of Volume of Heat Sink on Process and Physical Properties of Parts Built by Welding Based SFF

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f09f9223-3946-44a3-bbbd-50d6a596631b/download

null

A new numerical simulation of the effect of the volume of the heat sink on the welding–based deposition process is performed. For this purpose, the ANSYS parametric design language (APDL) is applied. Due to the complex internal and/or external shapes of the designed threedimensional (3D) part, different heat transfer conditions are met during the building process. The influences of the different heat transfer conditions on the physical part properties are also investigated. The influence of the volume of the heat sink on the process and on the physical properties is significant and can not be neglected. Extensive experiments are designed and executed in order to verify the conclusions derived from the finite elements model results and to investigate the material properties of the built part.

null

['Uí Mhurchadha, S.M.', 'Marques, S.', 'Givet, L.', 'Raghavendra, R.']

2021-11-30T22:20:59Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90569', 'http://dx.doi.org/10.26153/tsw/17488']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['high-cycle fatigue', 'metamaterials', 'laser powder bed fusion', 'fatigue life']

Effect of Voronoi Lattice Geometry on the Fatigue Performance of Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c467350b-a01a-4e7c-8032-e319e166627b/download

University of Texas at Austin

This paper investigates the effect of strut thickness and number of pores on the fatigue performance of Ti-6Al-4V voronoi lattice structures designed with the same part volume. The aim of this study is to establish the variation in high cycle fatigue parameters for constant volume lattice structures designed with various lattice parameters. Voronoi geometries were designed with varying strut thicknesses and number of pores to maintain a constant specimen volume. The geometries were tested under compressive fatigue conditions at a reversal ratio, R, of 0.1. It was found that the strut thickness has a significant influence on the fatigue life of the lattice. An increase in the strut thickness by 100 µm can result in a reduction in fatigue life by up to a factor of 10. The results from this research can influence the design of lattice structures for osteointegration in loadbearing biomedical implant applications.

null

['Spratt, Myranda', 'Anandan, Sudharshan', 'Hussein, Rafid M.', 'Newkirk, Joseph W.', 'Chandrashekhara, K.', 'Misak, Heath', 'Walker, Michael']

2021-11-09T20:04:21Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90150', 'http://dx.doi.org/10.26153/tsw/17071']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['wall thickness', 'build quality', 'strength', '304L', 'thin-walled structures', 'lattice structures', 'selective laser melting', 'finite element analysis']

Effect of Wall Thickness and Build Quality on the Compressive Properties of 304L Thin-Walled Structures Fabricated by SLM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d878e105-33fe-4dab-9c0a-db87bbab7af0/download

University of Texas at Austin

The specific strength of lightweight lattice structures built with SLM is of interest to the aerospace industry. Honeycombs were manufactured with increasing wall thicknesses (which increases density) and tested under compression. The optimal strength to density ratio was determined from the resulting data. The build quality was also evaluated to determine how/if the results were influenced by the specimen quality. Differences between the nominal and as-built geometry were identified, but considered to be minimal. Microstructural evaluation of the specimens revealed a possible dependence on the ‘border scan’ properties, as the thickness of the specimens was such that the board scan made up most of the part. This work was used to validate the results of a finite element analysis of this geometry.

null

['Davis, Joy E.', 'Klingbeil, Nathan W.', 'Bontha, Srikanth']

2021-09-28T20:07:48Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88170', 'http://dx.doi.org/10.26153/tsw/15111']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['laser beam-based fabrication', 'electron beam-based fabrication', 'additive manufacturing', 'repair applications', 'melt pool geometry', 'thin-wall structures', 'free-edges']

Effect on Free-Edges on Melt Pool Geometry and Solidification Microstructure in Beam-Based Fabrication of Thin-Wall Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e52529a4-08b2-4e65-a08b-2d1d7f548959/download

University of Texas at Austin

The success of both laser and electron beam-based fabrication processes for additive manufacturing and repair applications requires the ability to control melt pool geometry while still maintaining a consistent and desirable microstructure. To this end, previous work by the authors has employed point-heat source solutions to investigate the effects of process variables (beam power and velocity) on melt pool geometry and solidification microstructure (grain size and morphology) in beam-based fabrication of thin-wall structures. However, these results were limited to steady-state conditions away from free-edges. The current work extends the approach to investigate transient behavior in the vicinity of a free-edge.

null

['Kolan, Krishna C.R.', 'Leu, Ming C.', 'Hilmas, Gregory E.', 'Velez, Mariano']

2021-10-05T14:14:56Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88375', 'http://dx.doi.org/10.26153/tsw/15314']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', '13-93 bioactive glass', 'particle size', 'binder content', 'heat treatment']

Effect on Particle Size, Binder Content and Heat Treatment on Mechanical Properties of 13-93 Bioactive Glass Scaffolds

Conference paper

https://repositories.lib.utexas.edu//bitstreams/768fa75e-bfd0-4b0b-a25c-719c5b585e97/download

University of Texas at Austin

Particle size, binder content and the post-processing schedule are important parameters that affect the microstructure, and, hence, the mechanical properties of parts produced using the indirect selective laser sintering process. 13-93 bioactive glass, with mean particle sizes ranging from 10 µm to 44 µm, is mixed with different amounts of stearic acid binder to fabricate green scaffolds. Through the design of the post-processing schedule, the time required for postprocessing the green scaffolds is reduced from the initial 80 hrs to 12 hrs. The compressive strength varies from 41 MPa for a part with ~60% porosity to 157 MPa for a part with no designed porosity. Several batches of 13-93 scaffolds are soaked in a simulated body fluid for different time intervals ranging from 1 week to 6 weeks. The amount of hydroxyapatite formed and subsequent mechanical properties are provided and discussed.

null

['Song, Yong-Ak', 'Park, Sehyung', 'Kwon, Yongsin']

2019-10-09T16:04:49Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76147', 'http://dx.doi.org/10.26153/tsw/3236']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Casting

Effective Cooling Method for Spin Casting Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9db5f08e-2acd-412f-932a-4e7ed5ca4bee/download

null

Spin casting has been widely used in prototyping industry as a secondary process to convert a master model into a functional metal or plastic part. The main problem of the spin casting process consists in the poor thermal conductivity of silicone rubber as mold material which leads to a long cooling time between each casting processes and also to a short life time of mold. To solve this problem, different cooling methods have been developed and compared to each other experimentally. First, air cooling channel has been integrated into the spin casting mold to enhance the heat removal. Secondly, the silicone rubber has been mixed with different metal and ceramic powders to increase its thermal conductivity. The results so far prove an applicability of the developed cooling methods.

null

['Fashanu, O.', 'Murphy, D.', 'Spratt, M.', 'Newkirk, J.', 'Chandrashekhara, K.']

2021-11-30T21:31:06Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90555', 'http://dx.doi.org/10.26153/tsw/17474']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['unit-cell', 'elasticity', 'lattice structures', 'octet-truss', 'selective laser melting']

Effective Elastic Properties of Additively Manufactured Metallic Lattice Structures: Unit-Cell Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6fc16870-d5fd-4c7c-82af-ddf940660996/download

University of Texas at Austin

Lattice structures are lightweight materials, which exhibit a unique combination of properties such as air and water permeability, energy and acoustic absorption, low thermal conductivity, and electrical insulation. In this work, unit-cell homogenization was used to predict the effective elastic moduli of octet-truss (OT) lattice structures manufactured using selective laser melting (SLM). OT structures were manufactured using a Renishaw AM 250 SLM machine with various relative densities. Compression test was carried out at strain rate 5 × 10-3 m-1 using an MTS frame. Finite element analysis was used in the determination of the OT’s effective elastic properties. Results from the finite element analysis were validated using experiments. It was observed that the finite element predictions were in good agreement with the experimental results.

This work was funded by the Department of Energy’s Kansas City National Security Campus which is operated and managed by Honeywell Federal Manufacturing & Technologies, LLC under contract number DENA0002839.

null

['Loose, Kai', 'Niino, Toshiki', 'Nakagawa, Takeo']

2019-02-19T19:55:43Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73440', 'http://dx.doi.org/10.26153/tsw/592']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['LED', 'MPC']

Effective Mechanisms of Multiple LED Photographic Curing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dabce9a1-7148-41f0-bc50-abaea20ff70b/download

null

Multiple LED Photographic Curing (MPC) has proven capable of drawing cross sections of three-dimensional objects like printing a sheet of paper. Using raster scanning, however, simultaneously exposing a photopolymer with 1,024 beams of light involves various unknown issues. The aim of this research work was to examine the formation of individual strings and the connecting mechanisms between strings and layers. At light power ranging from 19.0 to 30.3flW and at various scan speeds, string formation perpendicular to scan direction differs greatly from that in scan direction. Curing of plane layers happens by curing strings side-by-side with a constant spacing of 62.5flm.

null

['Cook, D.', 'Newbauer, S.', 'Pettis, D.', 'Knier, B.', 'Kumpaty, S.']

2021-10-05T15:03:33Z

2011

Mechanical Engineering

null

['https://hdl.handle.net/2152/88388', 'http://dx.doi.org/10.26153/tsw/15327']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['multi-functional components', 'unit-lattice structures', 'thermal conductivities', 'orthosis', 'additive manufacturing', 'orthosis device']

Effective Thermal Conductivities of Unit-Lattice Structures for Multi-Functional Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f31e6774-364f-4b5a-9eba-79c0d0d4ab14/download

University of Texas at Austin

Approaching the goal of automatically generating optimized multi-functional components, previously-identified unit-lattice structures are being characterized for their geometry-dependent, effective, thermal conductivities. This knowledge base will allow for the definition of low-mass, load-bearing, thermal-management structures. One application is a wearable power source for a custom, portable, active orthosis. The function of this structure is to bear mechanical load while dissipating heat from the source, without burning the wearer. Additive manufacturing affords the capability of fabricating the resultant complex structures. Current research efforts are using finite-element analysis and physical testing to validate the characteristic models, and determining the scale dependence of internal-convective-flow development. Future work will include composites.

null

['Hasbrouck, C.R.', 'Bartolai, Joseph', 'Pagan, Darren C.', 'Miller, Simon W.']

2024-03-25T23:43:51Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124342', 'https://doi.org/10.26153/tsw/50950']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', '17-4PH stainless steel', 'thermal history', 'heat treatment']

EFFECTIVENESS OF EX-SITU HEAT TREATMENT OF L-PBF AM 17-4PH STAINLESS STEEL SPECIMENS INTENTIONALLY EXPOSED TO DIFFERENT AS-BUILT THERMAL HISTORIES

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2729e662-9e7b-4f12-8c78-977b9f1820e5/download

University of Texas at Austin

The presented research demonstrates the effectiveness of H900 heat treatment in eliminating microstructural and mechanical property differences between additively manufactured 17-4PH stainless steel samples of varying thermal histories. For this effort, 17-4PH stainless steel was manufactured using laser-based powder bed fusion on an EOS M280 machine in two geometries: ASTM Standard E8 subsize rectangular tensile specimen geometry with thicknesses of 2mm and 6mm. Thermal histories were manipulated by adding secondary laser passes on each layer at varying levels of reduced power. All samples were heat treated after the build following H900 procedures. Mechanical performance was evaluated with uniaxial quasi-static tensile testing and Vickers microhardness measurements. Metallography was examined qualitatively with optical and electron microscopy as well as quantitatively through electron backscatter diffraction. No statistically significant mechanical property or microstructural differences were discovered, suggesting a successful ex-situ heat treatment.

null

['Register, Matthew', 'Priddy, Matthew W.']

2023-01-27T17:50:40Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117347', 'http://dx.doi.org/10.26153/tsw/44228']

eng

2022 International Solid Freeform Fabrication Symposium

Open

WAAM

Effects Due to Variations in Thermal Properties of Maraging Steel for Finite Element Modeling of the WAAM Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ab92b0b7-5d7e-451b-82d3-97453ed78cbd/download

null

Finite element (FE) thermal simulations of the wire arc additive manufacturing (WAAM) process have been widely used to predict the temperature history of as-built parts. Temperature-dependent thermal properties like density, conductivity, specific heat, and latent heat are required to accurately simulate the solidus to liquidus transition seen in the heat affected zone. Current research has shown that thermal properties measured experimentally or simulated using material database software can be used for thermal modeling; however, there has been no direct comparison shown to determine which is most appropriate for WAAM modeling. The focus of this research is to compare the temperature variation of the FE thermal simulations with experimentally measured and computer-generated properties for M250 grade maraging steel. The thermal history for thin wall builds are compared with differing temperature-dependent thermal properties to examine the relationship between thermal properties and history. It was shown that constant values at room temperature result in an increased thermal response for WAAM thermal simulations and linearized properties decreased the temperature when both were compared with the experimental thermal property inputs. Further work needs to be performed before determining the most appropriate source for thermal properties (wrought, wire, as-built, or material database), but it can be concluded that the form of material does affect the thermal response for maraging grade 250 steel.

null

['Ottemer, Xavier', 'Colton, Jonathan S.']

2019-10-18T14:50:20Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76228', 'http://dx.doi.org/10.26153/tsw/3317']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Epoxy-Based

Effects of Aging on Epoxy-Based Rapid Tooling Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1bc1ef36-df6d-4b98-a7c4-731adbeab18c/download

null

This study shows the effects of aging on epoxy-based rapid tooling materials. Two epoxy-acrylate resins used for stereolithography and one aluminum powder-filled epoxy used for the high speed machining of plastic injection molds were selected to investigate their aging behavior in different environments. Four different conditions, each characterized by a specific relative humidity, were used to perform a seven week long aging study. Temperature was kept constant at 30°C. Both stereolithographic resins showed a drop in mechanical properties and in their glass transition temperatures in wet environments, whereas aging time showed little influence on these properties. Moisture uptake is mainly responsible for that drop and coefficients of water diffusion were determined. On the other hand, the aluminum powder-filled epoxy showed little humidity-dependent drop in mechanical properties and in its glass transition temperature during aging. This result correlates well with the very low moisture absorption of this material.

This work has been made possible thanks to the National Science Foundation (DMI9618039) and the Rapid Prototyping and Manufacturing Institute.

null

['Kriewall, Caitlin S.', 'Sutton, Austin T.', 'Karnati, Sreekar', 'Newkirk, Joseph W.', 'Leu, Ming C.']

2021-11-02T15:00:30Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89820

eng

2017 International Solid Freeform Fabrication Symposium

Open

['304L', 'stainless steel', 'area fraction', 'part spacing', 'selective laser melting']

Effects of Area Fraction and Part Spacing on Degradation of 304L Stainless Steel Powder in Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ce13f34d-5178-4886-9e90-96e15cdcd67b/download

University of Texas at Austin

In selective laser melting (SLM) systems, a large portion of powder remains unconsolidated and therefore recycling powder could make SLM more economical. Currently, a lack of literature exists specifically targeted at studying the reusability of powder. Furthermore, the definition of powder reusability is complex since powder degradation depends on many factors. The goal of the current research is to investigate the effects of area fraction and part spacing on the degradation of 304L powder in SLM. An experimental study was conducted where various area fractions and part distances were chosen and powder characterization techniques for determination of particle size distributions, tap and apparent densities, and x-ray diffraction were employed to track evolving powder properties for the purpose of reuse. The results show that the recyclability of 304L powder depends on the utilization of the build area causing varying degrees of particle size coarsening and delta ferrite formation.

null

['Andurkar, Mohanish', 'O-Donnell, Valentina', 'Gahl, John', 'Prorok, Bart', 'Keya, Tahmina', 'Harvill, Greyson', 'Thompson, Scott']

2021-12-06T22:51:29Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90705', 'http://dx.doi.org/10.26153/tsw/17624']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'nickel superalloy', 'nuclear radiation damage', 'Vickers microhardness', 'additive manufacturing']

Effects of Build Orientation and Heat Treatment on Neutron Irradiation Hardening in Inconel 625 Fabricated via Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0f227329-f912-4c09-99ef-1c8a20e14be2/download

University of Texas at Austin

Various Inconel 625 coupons fabricated via Laser Powder Bed Fusion (L-PBF) were neutron irradiated using the inside reflector of the reactor at the University of Missouri Research Reactor (MURR). Effects of build orientation and heat treatment on neutron-induced hardening were investigated by inspecting L-PBF samples built vertically or at a 45º angle in the following heat-treated conditions: as-built (no heat treatment), 700 ºC for 1 hour, 900 ºC for 1 hour, and 1050 ºC for 1 hour. The microhardness results of L-PBF samples before and after neutron irradiation were compared with traditional wrought Inconel 625. All samples underwent an irradiation flux of 6.61 x 1013 neutrons/cm²/s for 310 hours for an estimated damage of 0.012 dpa. Results indicate that as-built L-PBF specimens are less prone to radiation hardening relative to their wrought counterparts. As-printed diagonal specimens were shown to harden by 8% as compared to 1.2% hardening in as-printed vertical specimens.

null

['Andurkar, Mohanish', 'Prorok, Bart', 'Gahl, John', 'Thompson, Scott']

2024-03-25T23:46:29Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124343', 'https://doi.org/10.26153/tsw/50951']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'x-ray CT', 'porosity measurements', 'pore morphology']

Effects of Build Orientation and Heat Treatment on the Porosity Distribution and Morphology within Inconel 625 Fabricated via Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/82089975-1ff6-4146-8fb2-e8c6cd5df93e/download

University of Texas at Austin

The effects of build orientation, i.e., vertical, or diagonal (45º), and heat treatment on the porosity characteristics within Inconel 625 (IN625) fabricated via laser powder bed fusion (LPBF) was experimentally investigated. Selected samples were heat treated at 1050 ℃ for 1-hour to promote evolution of pores. X-Ray Computed Tomography (XCT) was performed on samples to generate three-dimensional porosity maps. Volume Graphics (VG) software was used to inspect and quantify porosity distributions. Results indicate that build orientation and heat treatment influence measured porosity count. As-built (no heat treatment) sample microstructure was observed to have lower porosity count when compared to heat-treated samples. The vertically built sample was observed to have lower porosity relative to its diagonally built counterpart. The porosity morphology or diameter was observed to vary after heat treatment. On the other hand, the sphericity of pores was not affected by different build orientation and heat treatment.

null

['Motaparti, Krishna P.', 'Taylor, Gregory', 'Leu, Ming C.', 'Chandrashekhara, K.', 'Castle, James', 'Matlack, Mike']

2021-10-28T14:22:01Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89647

eng

2016 International Solid Freeform Fabrication Symposium

Open

['compression properties', 'build parameters', 'ULTEM 9085', 'fused deposition modeling']

Effects of Build Parameters on Compression Properties for ULTEM 9085 Parts by Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/09236221-0f00-41b0-9ea1-49e6a37e3bbb/download

University of Texas at Austin

It has been observed by various researchers that parts fabricated by the Fused Deposition Modeling (FDM) process have anisotropic properties. The research presented in the present paper was aimed to study the compression properties of FDM parts and to comprehend their dependence on build parameters. In this study Ultem 9085 was used as the material to fabricate both solid and sparse-build coupons with variations in build direction, raster angle and air gap. A full factorial experimental design was used to study the individual and combined effects of these build parameters on the mechanical properties of the coupons. The mechanical properties studied include compressive yield strength, compressive modulus, compressive strength/mass ratio, and compressive modulus/mass ratio. Besides the obtained test data, qualitative observation and reasoning was used to help understand how the compression properties are affected by the build parameters.

null

['Munaganuru, Sai Sri Nidhi', 'Elenchezian, Muthu Ram Prabhu', 'Vadlamudi, Vamsee', 'Shaik, Rauhon Ahmed', 'Adluru, Hari Kishore', 'Raihan, Rassel', 'Reifsnider, Kenneth']

2021-11-11T16:02:21Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90227', 'http://dx.doi.org/10.26153/tsw/17148']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['build parameters', 'mechanical properties', 'di-electrical properties', 'additive manufacturing']

Effects of Build Parameters on the Mechanical and Di-Electrical Properties of AM Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bc32c38c-580e-486c-b7fc-e1ecd1aa9282/download

University of Texas at Austin

Additive manufacturing (AM) revolutionized many industries, i.e., Automotive, Biomedical, Aerospace and Defense. As opposed to traditional manufacturing methods, a part is manufactured layer by layer from 3D CAD models in AM. Though the vision of AM is impressive, there are many challenges that are hindering the widespread use of these complex parts. One of the challenges in these materials is defects grow and their orientation during the manufacturing process. In this paper we are going to investigate the effect of Build Parameters and their effects on the mechanical and electrical properties of the additively manufactured heterogeneous material system. We will study the electrical properties to find out the material state of additively manufactured part.

null

['Fan, Foxian', 'Soares, Nicholas', 'Jalui, Sagar', 'Isaacson, Aaron', 'Savla, Aditya', 'Manogharan, Guha', 'Simpson, Tim']

2021-12-07T19:04:52Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90759', 'http://dx.doi.org/10.26153/tsw/17678']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['centrifugal disc finishing', 'AM surface finishing', 'AM gears', 'surface roughness', 'CT roughness measurements', 'powder bed fusion']

Effects of Centrifugal Disc Finishing for Surface Improvements in Additively Manufactured Gears

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1bda4710-1aaf-4af4-9f61-f99b7a9f309b/download

University of Texas at Austin

Additive Manufacturing (AM) is well suited to rapidly produce complex and customized geometries economically for low production runs. However, there is an inherent need for post-AM machining and surface finishing in most metal AM applications. Centrifugal Disc Finishing (CDF) is a media-based mass finishing process that can be employed to improve surface finish of external surfaces of AM parts with complex geometry. This original study aims to understand the influence of CDF processing conditions on Ti64 gear teeth fabricated via Powder Bed Fusion (PBF). A detailed statistical analysis is conducted to analyze the effectiveness of CDF to improve surface roughness of different build surfaces of the AM gear teeth. In addition, both contact profilometer and X-ray Computer Tomography (CT) techniques are applied to evaluate its effectiveness to measure CDF and AM surface finishing. Findings from this study on CDF of gear AM will benefit metal AM community by better understanding the impact of CDF processing conditions for surface improvements in mass finishing of metal AM parts.

null

['Fuentes, F.', 'Gallardo Jr., A.', 'Martinez, J.', 'Bullman, J.', 'Foyos, J.', 'Mendelson, M.', 'Noorani, R.', 'Fritz, B.']

2019-10-22T18:17:24Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76333', 'http://dx.doi.org/10.26153/tsw/3422']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Cryogenic

Effects of Cryogenic Aging on a Rapid Prototyped (RP) Polymer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/802364f2-948a-47d9-af0c-1c9260db8a31/download

null

Little research has been done on the post-processing (aging) of rapid prototyped (RP) polymers at temperatures below 123K (–238˚F). Test specimens of RP thermosetting resin (DSM-Somos 8110) were fabricated and cryogenically aged from 10-25 hours. The tensile strength and impact toughness were measured. This work will study the effect of cryogenic aging on yield strength of Somos 8110. This paper will also discuss our interpretation of the data based on fractography.

The work was funded by an NSF Grant under Research Experiences for Undergraduates (REU).

null

['Jackson, J.', 'Chapple, G.', 'Do, J.', 'Zhuang, X.', 'Bulman, J.', 'Foyos, J.', 'Mendelson, M.', 'Noorani, R.', 'Fritz, B.']

2019-11-21T18:42:37Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78565', 'http://dx.doi.org/10.26153/tsw/5621']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Prototyping Materials

Effects of Cryogenic Processing on Rapid Prototyping Materials (DSMSomos-8110 and DuraForm PA)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/186d87c6-d505-4cd3-b358-b85d589f47d4/download

null

This research investigates the effects of cryogenic processing on the properties of rapid prototyped materials. Not much research has been done on the post-processing (aging) of rapid prototyped (RP) polymers at temperatures below 159K (–173˚F). Test specimens of RP thermoplastic resin DSM-Somos 8110 and DuraformPA Nylon were fabricated and cryogenically aged from 5-30 hours. The tensile strength and impact toughness were measured. The goal of this work was to study the effect of cryogenic aging on yield strength and ductility. This research investigated (1) the cryogenic aging of DSM-Somos 8110 and DuraformPA Nylon, (2) the effects of controlled ramp-downs/ups on the ultimate and tensile strengths of samples, (3) the experimental methods, and (4) the analysis and interpretation of the data.

Part of this work was funded by a NSF Grant under Research Experiences for Undergraduates.

null

['Fan, K.M.', 'Cheung, W.L.']

2019-09-20T18:23:38Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75926', 'http://dx.doi.org/10.26153/tsw/3025']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Sintering

Effects of Cu and SiO2 on Laser Sintering of Polycarbonate 110

Conference paper

https://repositories.lib.utexas.edu//bitstreams/11f10eaa-20ff-47b3-b318-3b00c160c0a6/download

null

Additives of different thermal properties, Cu and SiO2 (amorphous and crystalline), were blended to polycarbonate (PC) powder to modify its heat transfer properties and fusion behavior during laser sintering. The blends were sintered under different energy densities of the laser beam to produce mono-layer films. The surface morphology and the thickness of the films were studied. When sintering under the same condition, the composite films which contained a high content of Cu powder exhibited a more porous surface structure. This was caused by the increased heat loss because the Cu powder has a higher thermal conductivity. Also, the solid Cu particles would hinder the flow of the molten polymer, resulting in a low degree of fusion. For a given Cu powder content, reducing its particle size gave a more porous surface structure and a smaller thickness of the sintered films. This was probably due to a more even distribution of the fine Cu particles, which increased the heat loss and reduced the effective amount of energy for fusion. On the other hand, fine SiO2 and quartz powders caused degradation of the polymer because of the increased energy dissipation near the film surface and poor heat transfer properties of the additives comparing with Cu.

null

['Majewski, C. E.', 'Zarringhalam, H.', 'Hopkinson, N.']

2020-03-10T17:04:53Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80230', 'http://dx.doi.org/10.26153/tsw/7249']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Differential Scanning Calorimetry

Effects of Degree of Particle Melt and Crystallinity in SLS Nylon-12 Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/118e0bfa-74e8-4d49-b646-8c3d96ad9c02/download

null

Differential Scanning Calorimetry (DSC) traces for SLS Nylon-12 parts display two distinct melt peaks, which have been related to the presence of both melted and crystallised regions, and un-melted particle cores within the part. The relative proportions of each region are defined by the term ‘Degree of Particle Melt’ (DPM), and have a large effect on the mechanical properties of a part. This paper demonstrates that the % crystallinity of SLS Nylon-12 parts is dependent on the DPM. Crucially, research has also shown that the trends for some tensile properties (notably Tensile Strength and Young’s Modulus) change once full melting is complete.

null

['Shrestha, Rakish', 'Nezhadfar, P. Dastranjy', 'Masoomi, Mohammad', 'Simisiriwong, Jutima', 'Phan, Nam', 'Shamsaei, Nima']

2021-11-10T23:08:47Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90205', 'http://dx.doi.org/10.26153/tsw/17126']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['fatigue', 'thermal simulation', 'additive manufacturing', 'laser-based powder bed fusion', 'L-PBF']

Effects of Design Parameters on Thermal History and Mechanical Behavior of Additively Manufactured 17-4 PH Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/02b026f1-7940-438e-b232-4acf7a9e39ea/download

University of Texas at Austin

In this study, the effects of part size on thermal history and mechanical properties of additively manufactured 17-4 PH stainless steel were investigated under monotonic tensile and strain-controlled fatigue loadings. Two sets of specimens were machined from square rods and oversized specimens, which were fabricated using a laser bed powder fusion (L-PBF) process, to introduce variation in specimen geometry and consequently thermal history. Monotonic tensile tests were conducted at a strain rate of 0.001 s-1 . Fully-reversed (Rε = -1), strain-controlled fatigue tests were performed at 0.003 and 0.0035 mm/mm, and varying test frequency to maintain a constant average strain rate in all tests. Experimental results indicated minimal effect of specimen geometry on the tensile properties of L-PBF 17-4 PH SS, which were also found to be comparable to the wrought material. On the other hand, some influence of specimen geometry on fatigue behavior was observed. Specimens machined from square rods exhibited slightly higher fatigue resistance as compared to specimens machined from oversized specimens. Furthermore, thermal simulations demonstrated higher bulk heating in specimens machined from oversized specimens as compared to those from square rods, which indicated the effect of part geometry on thermal history experienced by the fabricated part.

null

['Lares, J.', 'Godinez, D.', 'Arrieta, E.', 'Medina, F.', 'Wicker, R.', 'Gradl, P.', 'Katsarelis, C.']

2024-03-25T23:02:19Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124333', 'https://doi.org/10.26153/tsw/50941']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['NASA HR-1', 'direct energy deposition', 'deposition parameters', 'microstructure']

EFFECTS OF DIFFERENT PARAMETERS ON DED HR-1 ON LOW CYCLE FATIGUE, TENSILE STRENGTH, AND MICROSTRUCTURE

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fac45921-e0ff-445b-b11d-cdb3cddc4bc1/download

University of Texas at Austin

NASA HR1 alloy is an iron-nickel based material designed by NASA and derived from A286 and JBK-75 alloys. At extreme conditions, NASA HR1 possess high strength, high fatigue resistance, and high resistance to corrosion and hydrogen embrittlement. The main applications include structural components and liquid rocket engine nozzles with internal cooling channels. NASA has produced HR1 using vacuum induction melting (VIM), a considerably expensive fabrication method. Aimed to explore other more affordable and accessible manufacturing methods, HR1 specimens were fabricated under different parameters using Laser-Powder Directed Energy Deposition (LP-DED) and were heat treated through stress relief, homogenization, solution treatment and aging. The feasibility of this AM process was investigated by evaluating mechanical and microstructural analysis on specimens. This work finalizes with discussion and remarks on tensile and low-cycle fatigue properties and its relationship with microstructural features.

null

['George, Mitchell J.', 'Crawford, Richard H.']

2021-10-04T19:55:01Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88329', 'http://dx.doi.org/10.26153/tsw/15268']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Sintering', 'medical sterilization', 'nylon parts', 'dry heat sterilization', 'surgical tooling', 'bone matrices']

The Effects of Dry Heat Sterilization on Parts Using Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a94a355b-488b-4d66-b8b4-7371b76a4d1a/download

University of Texas at Austin

Selective Laser Sintering (SLS) is a manufacturing process that can build arbitrarily shaped parts without part specific tooling. Its advantages have been employed in many different fields, one of these being medical surgery. Currently, SLS is limited in medical applications as a pre-operative modeling tool. For SLS manufacturing to progress in areas like compliant surgical tooling and patient specific bone matrices, concurrent work is needed to investigate the effects of medical sterilization on SLS materials. This paper presents the results of sterilization experiments on SLS parts built from nylon 11. To simulate the process of introducing tools into a sterile environment, these specimens were subjected to multiple rounds of dry heat sterilization. Changes to the dimensions, tensile strength and flexibility were recorded and analyzed. It was found that the specimens’ dimensions remained relatively constant. Both the tensile modulus and the flexural modulus decreased as the sterilization cycles progressed. The tensile modulus decreased by 25% and the flexure modulus decreased by 19% after ten rounds of sterilization.

null

['Hagen, Deborah', 'Kovar, Desiderio', 'Beaman, Joseph J.']

2021-11-09T21:03:12Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90166', 'http://dx.doi.org/10.26153/tsw/17087']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['electric field', 'laser scanning', 'selective laser sintering', 'ceramic powder', 'yttria-stabilized zirconia']

Effects of Electric Field on Selective Laser Sintering of Yttria-Stabilized Zirconia Ceramic Powder

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d567f84d-6052-4d11-b75e-4379fa8c1437/download

University of Texas at Austin

Selective laser sintering (SLS) of ceramic material is particularly challenging. High sintering temperatures and slow sintering kinetics of ceramic material combined with poor thermal shock resistance have resulted in cracking when ceramics are sintered to full density one layer at a time. This work investigates the use of an electric field applied simultaneously with laser scanning to accelerate the kinetics of sintering to produce a multi-layer SLS ceramic part. Ceramic sintering rates have been shown to increase by orders of magnitude during conventional furnace-based flash sintering, in which electric field applied simultaneously with furnace heating. In this work, we investigate the effects of an electric field applied during SLS processing of yttria-stabilized zirconia ceramic.

null

['Andurkar, M.', "O'Donnell, V.", 'Keya, T.', 'Prorok, B.C.', 'Gahl, J.', 'Thompson, S.M.']

2023-03-30T16:04:30Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117695', 'http://dx.doi.org/10.26153/tsw/44574']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'Nickel Superalloy', 'Vickers Microhardness', 'Radiation Embrittlement']

Effects of Fast Neutron Irradiation on the Microhardness of Inconel 625 and Inconel 718 Fabricated via Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/90692cb0-34b9-4e37-b78a-912445aeec28/download

null

The demand for advanced materials in constructing next generation nuclear reactors has intensified the need to explore additive manufacturing (AM) processes as an alternate means of fabricating components. In this study, Inconel 625 (IN625) and Inconel 718 (IN718) samples fabricated using Laser Powder Bed Fusion (L-PBF) were irradiated using fast neutrons. Samples investigated included as-printed and heat-treated at either 700, 900, or 1050 ℃ for 1 hour to understand the impact of heat treatment on any neutron irradiation hardening. Wrought IN625 and IN718 samples were also inspected for experimental control. All samples were irradiated for 7 weeks resulting in a total fluence 2.74x10 15 neutrons/cm 2. To quantify radiation damage, the Vickers microhardness was measured before and after fast neutron irradiation. Results show that the IN718 samples experienced less change (-2.5 to 3.24 %) in microhardness. On the other hand, IN625 samples underwent more (0.9 to 7.21%) change in microhardness post fast neutron irradiation.

null

['Burkert, T.', 'Fischer, A.']

2021-10-20T22:08:50Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89375

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'Direct Metal Laser Sintering', 'Lasercusing', 'Maraging Steel', 'heat balance', 'mechanical properties', 'energy input', 'preheat temperature', 'void', 'defect']

The Effects of Heat Balance on the Void Formation within Marage 300 Processed by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/398d648b-d4fd-40ff-af87-7474059eb078/download

University of Texas at Austin

This contribution shows the results of a study that was conducted on the effects of varying selective laser melting (SLM) process parameters on the formation of microstructural voids within a maraging steel (type: Marage 300, 1.2709, AMS6514). Due to the large number of process variables the most influential parameters were identified first. These were energy input resulting from scanning speed, hatch distance, and layer thickness as well as the preheating of the platform. On the basis of the variation of these parameters the most abundant voids were identified and characterized by metallographic investigations. Subsequently tensile tests derived information about the influence of such voids on the mechanical properties. Based on these analyses the reasons for the generation of such voids are discussed followed by strategies in order to prevent them. This allowed for the well-aimed optimization of the processing parameters resulting in a nearly void-free SLM processing of such maraging steel parts.

null

['Keya, T.', "O'Donnell, V.", 'Lieben, J.', 'Romans, A.', 'Harvill, G.', 'Andurkar, M.', 'Gahl, J.', 'Thompson, S.M.', 'Prorok, B.C.']

2021-12-06T22:54:26Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90706', 'http://dx.doi.org/10.26153/tsw/17625']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['heat treatment', 'neutron irradiation', 'Inconel 625', 'microstructure', 'microhardness', 'laser-powder bed fusion', 'L-PBF']

Effects of Heat Treatment and Fast Neutron Irradiation on the Microstructure and Microhardness of Inconel 625 Fabricated via Laser-Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/01b3261f-159d-4c8f-81a8-529a024962d6/download

University of Texas at Austin

The microstructure of Inconel 625 fabricated via Laser-Powder Bed Fusion (L-PBF) was investigated in as-printed and heat-treated conditions. The very high cooling rates inherent to the L-PBF process generally result in fine microstructures and complex residual stress fields which requires annealing to reduce stress and tailor the microstructure to obtain the desired mechanical properties. Inconel 625 alloy, a nickel-based superalloy, continues to be a common material employed with the L-PBF process. The unique microstructure produced by the L-PBF process and different phases introduced by different heat treatment processes require investigation to facilitate the material’s wide range of applications. This paper investigates the influence of heat treatments at 700°C, 900°C and 1050°C for one hour on the microstructure and microhardness of the L-PBF parts. The parts were irradiated using ‘fast’ neutrons in University of Missouri Research Reactor Center (MURR). The microhardness before and after radiation are also compared.

null

['Cullom, Tristan', 'Hartwig, Troy', 'Brown, Ben', 'Johnson, Kevin', 'Blough, Jason', 'Barnard, Andrew', 'Landers, Robert', 'Bristow, Douglas', 'Kinzel, Edward']

2021-11-15T22:35:53Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90298', 'http://dx.doi.org/10.26153/tsw/17219']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['build plate', 'coupling', 'modal analysis', 'frequency response function', 'selective laser melting']

Effects of Identical Parts on a Common Build Plate on the Modal Analysis of SLM Created Metal

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c198cf13-e563-4fc4-a5fc-55d2e35d9eb7/download

University of Texas at Austin

The frequency response of parts created with Additive Manufacturing (AM) is a function of not only process parameters, powder quality, but also the geometry of the part. Modal analysis has the potential to evaluate parts by measuring the frequency response which are a function of the material response as well as the geometry. A Frequency Response Function (FRF) serves as a fingerprint of the part which can be validated against the FRF of a destructively tested part. A practical scenario encountered in Selective Laser Melting (SLM) involves multiple parts on a common build plate. Coupling between parts influences the FRF of the parts including shifting the resonant frequencies of individual parts in ways that would correspond to changes in the material response or geometry. This paper investigates the influence of the build plate properties on the coupling phenomena.

This work was funded by the Department of Energy’s Kansas City National Security Campus which is operated and managed by Honeywell Federal Manufacturing Technologies, LLC under contract number DE-NA0002839.

null

['Nigam, Aman', 'Tai, Bruce L.']

2021-12-07T18:51:47Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90756', 'http://dx.doi.org/10.26153/tsw/17675']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['fiber-reinforced polymer', 'fused filament fabrication', 'FFF', 'hybrid process', 'polishing', '3D printing', 'surface roughness']

Effects of In-Situ Mechanical and Chemical Polishing on Surface Topography of Additively Manufactured Fiber-Reinforced Polymers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8fd121c8-285d-4dc2-97a5-1f3e113d2b02/download

University of Texas at Austin

Additive manufacturing of fiber-reinforced polymers (FRPs) has revolutionized fused filament fabrication (FFF) by producing polymeric parts with enhanced mechanical properties. However, FFF suffers from poor surface quality and dimensional accuracy, particularly for FRPs, due to their abrasive and rheological nature. This examines an in-situ polishing scheme for FRPs in the FFF configuration. Glass-fiber-reinforced Nylon was used as the study material. Three polishing schemes, mechanical, chemical, and a combined thereof, were adopted along with various parameters in each case. The results show significant surface improvements in all cases, and the combined process can further reduce the Ra value to around 2 μm and the dimensional error to 0.2 mm and less. The combined process also enhances surface uniformity (i.e., similar Ra in all directions). In particular, with the combined approach, the in-situ polishing scheme is expected to improve the quality of 3D printed FRPs significantly.

null

['Masoomi, Mohammad', 'Thompson, Scott M.', 'Shamsaei, Nima', 'Bian, Linkan']

2021-10-26T18:16:11Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89548

eng

2016 International Solid Freeform Fabrication Symposium

Open

['temperature gradients', 'directed energy deposition', 'Ti-6Al-4V', 'residual stress']

Effects of Inter-Layer Time Interval on Temperature Gradients in Direct Laser Deposited Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f1500151-387e-4bb8-9f97-b504b43711c5/download

University of Texas at Austin

Parts fabricated via additive manufacturing (AM) methods are prone to experiencing high temperature gradients during manufacture resulting in internal residual stress formation. In the current study, a numerical model for predicting the temperature distribution and residual stress in Directed Energy Deposited (DED) Ti–6Al–4V parts is utilized for determining a relationship between local part temperature gradients with generated residual stress. Effects of time-interval between successive layer deposits, as well as layer deposition itself, on the temperature gradient vector for the first and each layer is investigated. The numerical model is validated using thermographic measurements of Ti-6Al-4V specimens fabricated via Laser Engineered Net Shaping® (LENS), a blown-powder/laser-based DED method. Results demonstrate the heterogeneity in the part’s spatiotemporal temperature field, and support the fact that as the part number, or single part size or geometry, vary, the resultant residual stress due to temperature gradients will be impacted. As the time inter-layer time interval increases from 0 to 10 second, the temperature gradient magnitude in vicinity of the melt pool will increase slightly.

null

['Fulcher, Ben', 'Leigh, David K.']

2021-10-07T15:50:20Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88487', 'http://dx.doi.org/10.26153/tsw/15421']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['laser power', 'laser sintering', 'laser window', 'laser distribution', 'degradation']

Effects of Laser Window Degredation on Laser Power and Distribution in Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/29ccf6ba-4fb7-45f2-b375-8ae7c1f29098/download

University of Texas at Austin

Laser power is a key parameter in the laser sintering (LS) process, and tight control on laser power is necessary to produce quality parts with desirable mechanical properties. Unfortunately, temperature limitations hinder real-time monitoring and feedback of laser power within the process chamber. Therefore, in order to maintain consistent laser power during an LS build, the laser window, which provides a barrier between the processing chamber and the laser housing, must remain clean throughout the build. However, material outgassing leads to the buildup of condensation on the window, thereby reducing the amount of energy imparted to the powder bed. The buildup of condensation also necessitates frequent cleaning of the laser window and significantly reduces its life. Thus, laser window replacement is a large source of cost in a production environment. To compensate for the loss of laser power through the window, current practice is to steadily increase the laser power at the laser source during the build. This practice can be largely inaccurate, as it is difficult to predict the loss of laser power through the window at various stages in a given LS build. Thus, to achieve consistent mechanical properties in this manner, a trial and error-based approach is used. The study presented in this paper aims to characterize laser power and distribution for various levels of laser window degradation. In addition, methods to reduce or eliminate the buildup of condensation on the laser window are explored in an effort to improve the consistency of part quality, as well as to reduce maintenance requirements and costs.

null

['Carrion, Patricio', 'Imandoust, Aidin', 'Simsiriwong, Jutima', 'Shamsaei, Nima']

2021-11-11T15:10:32Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90214', 'http://dx.doi.org/10.26153/tsw/17135']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'failure mechanisms', 'mutliaxial fatigue', 'titanium']

Effects of Layer Orientation on the Multiaxial Fatigue Behavior of Additively Manufactured Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d1088aba-472f-4728-9e25-9c4568711ec3/download

University of Texas at Austin

Additive manufacturing (AM) allows for fabrication of components with complex geometries that cannot be fabricated using conventional manufacturing techniques. These components are often subjected to multiaxial stress states due to their typically complex design accompanied by residual stresses and/or multiaxial external loading. Therefore, understanding the fatigue behavior of AM materials under multiaxial-type loadings is necessary for ensuring reliable in-service component performance. In this study, the effects of layer orientation on the multiaxial fatigue behavior of Ti-6Al-4V fabricated via a laser-powder bed fusion (L-PBF) process was investigated. Tubular thin-walled multiaxial specimens were fabricated in vertical and diagonal orientations with respect to the build plate. Specimens were tested under axial, torsional, in-phase axial/torsional, and 90° out-of-phase axial-torsional cyclic loadings. Upon failure, the crack orientation of vertical and diagonal specimens was correlated to the type of loading, which illustrated the failure mechanism of L-PBF Ti-6Al-4V and justified the variations in the fatigue lives of specimens.

null

['Wang, Zhaogui', 'Fang, Zhenyu', 'Smith, Douglas E.']

2021-12-07T17:50:28Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90735', 'http://dx.doi.org/10.26153/tsw/17654']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['fiber orientation state', 'polymer deposition', 'material properties', 'mechanical properties', 'large area additive manufacturing']

Effects of Local Fiber Orientation State on Thermal-Mechanical Behaviors of Composite Parts Made by Large Area Polymer Deposition Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/70d09119-a475-4a68-9c60-38fa3fafe94a/download

University of Texas at Austin

Short carbon fiber enhances the dimensional stability and material strength of composite parts created via large area polymer deposition additive manufacturing, which has been used for rapid fabrications of large-dimension composite parts and tooling. Nevertheless, the flow-induced fiber orientation formed during the material extrusion and deposition leads the deposited composites exhibit non-homogeneous thermal-mechanical behaviors. This study evaluates the fiber orientation state of a 20 wt.% CF-PEI composite fabricated by polymer deposition using the fully coupled flow/orientation approach. The material properties are computed by considering the deposited bead as heterogeneous segments with different local fiber orientation states. The heterogeneous thermal conductivity and expansion coefficient exhibit maximum local differences of 29% and 21%, respectively. The orientation-homogenized material properties are implemented to the finite element simulation for a large area additive manufacturing process of a single bead and notable differences are seen between results computed by employing the homogenous and heterogeneous properties.

null

['Zhang, Ying', 'Jariwala, Amit', 'Rosen, David W.']

2021-10-19T20:24:23Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89332

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Exposure Controlled Projection Lithography', 'process planning', 'post-processing', 'oxygen inhibition']

Effects of Oxygen Inhibition and Post-Processing on Exposure Controlled Projection Lithography Process Accuracy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/331fbefe-39a6-4547-85ce-016b54be775c/download

University of Texas at Austin

Exposure Controlled Projection Lithography (ECPL) is a mask-projection stereolithography process which can be used to create micro lenses on flat or curved substrates. In the ECPL process, the ultraviolet light patterned by the dynamic mask passes through a transparent substrate to cure the photopolymer resin to a certain shape. The dimensions of the part can be controlled by the exposure time and functional pixels in the dynamic mask. In this paper, a modified process planning method is presented with the considerations of postprocessing and oxygen inhibition, which can vary part dimensions significantly. The effects of post-processing and oxygen inhibition are studied and characterized. The accuracy of the lateral and vertical dimensions of the cured part are improved by the revised method. Experimental validation is obtained by fabricating samples using the ECPL system.

null

['Lim, J.H.', 'Khan, N.A.']

2021-11-30T20:20:48Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90534', 'http://dx.doi.org/10.26153/tsw/17453']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['particle size distribution', 'surface finish', 'Inconel 625', 'selective laser melting']

Effects of Particle Size Distribution on Surface Finish of Selective Laser Melting Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/860839a0-b54e-4e96-896e-5eb722a183c8/download

University of Texas at Austin

Metal parts produced by Selective Laser Melting (SLM) usually exhibit poor surface finish compared to conventional manufacturing processes. There is a growing need for parts to have good surface quality in the as-built condition to minimise post-processing costs and reduce lead time. There are many studies done on the effects of processing parameters on surface finish but very little on the influence of powder characteristics. This study aims to investigate the effects of Particle Size Distribution (PSD) on surface finish of AM parts by printing coupons with Inconel 625 powders of varying PSD. It was found that roughness of internal surfaces was mainly caused by the presence of partially sintered particles. Whilst a smaller particle mean size and wider particle size range are preferred for better surface finish, a powder that is too fine may result in poor flowability affecting its processability in terms of layering and powder bed quality.

null

['Obielodan, J.O.', 'Stucker, B.E.']

2021-09-29T14:11:46Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88177', 'http://dx.doi.org/10.26153/tsw/15118']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['ultrasonic consolidation', 'post processing heat treatment', 'titanium material', 'aluminum material', 'bond quality', 'mechanical strength', 'Ti/Al3003']

Effects of Post Processing Heat Treatments on the Bond Quality and Mechanical Strength of Ti/Al3003 Dual Materials Fabricated using Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4cb691fc-01e1-415a-86ec-9a55a029eb89/download

University of Texas at Austin

The interface between layers in ultrasonically fabricated parts is often poor for desirable material combinations, resulting in relatively low bond strength. This makes these fabrications unsuitable for structural applications. This work discusses a study of the effects of post processing heat treatment of ultrasonically consolidated titanium and aluminum dual-material specimens. The shear strengths of as-deposited specimens as well as heat treated ones were tested. The results show that there is significant improvement of the strengths of post processed specimens over the as-fabricated ones. The improvement is as a result of interactions of the base materials across the interfacial boundaries at elevated temperatures, leading to stronger bonds. The study highlights the role of post processing for improving the mechanical properties of ultrasonically consolidated structures.

null

['Koju, Naresh', 'Hermes, Jonah', 'Paul, Sumit', 'Saghaian, Sayed Ehsan', 'Yang, Li']

2023-02-24T14:49:39Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117525', 'http://dx.doi.org/10.26153/tsw/44405']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Lightweight features', 'thin struts', 'powder feedstock', 'powder bed fusion', 'porosity', 'microstructure', 'strength']

The effects of powder feedstock and process parameters on the material characteristics of Ti6Al4V thin strut features fabricated by laser powder bed fusion additive manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aa616203-8e72-44dc-9047-f8fdf7d50404/download

null

In this work, three different types of Ti6Al4V powder feedstock of different particle size ranges (fine, medium, and coarse) were utilized to fabricate thin strut lightweight features using laser powder bed fusion additive manufacturing (L-PBF-AM) using different process parameter settings. Thin strut features of varying dimensions from 0.1mm to 0.5mm were fabricated. The resulting sample sets allow for the analysis of the compound powder feedstock-process- geometry-material (PPG-M) characteristics for lightweight features fabricated by L-PBF-AM, which have not been previously explored. Various material characteristics were experimentally determined and analyzed, including success rate, geometry quality, porosity, pore size, grain size, and mechanical properties of the lightweight thin strut samples. The results clearly demonstrated the significance of the compound PPG-M relationships for lightweight structures, which calls for further studies to “re-establish” the knowledge base for L-PBF-AM materials at small dimension scales.

null

['Nezhadfar, Pooriya Dastranjy', 'Soltani-Tehrani, Arash', 'Sterling, Amanda', 'Tsolas, Nicholas', 'Shamsaei, Nima']

2021-11-10T23:23:36Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90206', 'http://dx.doi.org/10.26153/tsw/17127']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['17-4 PH stainless steel', 'laser powder bed fusion', 'powder characterization', 'powder recycling', 'mechanical properties', 'tensile behavior']

The Effects of Powder Recycling on the Mechanical Properties of Additively Manufactured 17-4 PH Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e6b45358-89d3-4a0e-9f2f-50684d29dc5a/download

University of Texas at Austin

The booming interest in Additive Manufacturing (AM), is seeing a rising number of industries and research entities adopting this technology into their manufacturing practices. Of particular interest is Laser Powder Bed Fusion (L-PBF) process, a common AM method for fabricating metallic components. However, one obstacle is the high cost of powder feedstock. A popular tactic to offset this cost is to reuse the powder between prints, but there is no in-depth understanding of how the powder feedstock may change or affect the mechanical properties of the produced parts. By incorporating unique powder/part characterization methods, this study quantifies the rheological properties of continually recycled 17-4 precipitation hardening (PH) stainless steel (SS) powder through successive printing of mechanical test specimens. The AM specimens are subjected to tensile tests, to correlate mechanical behavior to changing powder quality, including particle size/shape distribution, flowability, and density.

null

['Soltani-Tehrani, Arash', 'Yasin, Mohammad Salman', 'Shao, Shuai', 'Shamsasei, Nima']

2021-12-06T23:08:52Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90710', 'http://dx.doi.org/10.26153/tsw/17629']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'L-PBF', 'powder recycling', 'Ti-6Al-4V', 'particle size distribution', 'PSD', 'location dependency', 'packing state', 'powder flowability']

Effects of Powder Reuse and Spatial Location Dependency on the Powder Characteristics and Defect Structure of Additively Manufactured Ti-6Al-4V Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/13d67006-9662-4b26-8c0e-1d754de6d26b/download

University of Texas at Austin

In laser powder bed fusion additive manufacturing (L-PBF AM), different powder characteristics including particle size and morphology may yield different packing states and thus different defect content in the resulting parts. As the powder is spread by the recoater, the packing state may not be uniform on the powder bed, giving rise to location-dependent part performance. In addition, as the powder is reused (a common practice in AM industry), its characteristics continuously evolve, causing the defect content to change from build to build. This study aims to investigate the effects of powder reuse and part location on powder characteristics as well as the defect structure of the parts. Results indicate powder reuse in an L-PBF system may reduce the number of defects in the as-fabricated parts due to the superior packing state of reused powder. Part density was also found to be location-dependent, with more defects near the gas outlet.

null

['Gu, Hengfeng', 'Gong, Haijun', 'Dilip, J.J.S.', 'Pal, Deepankar']

2021-10-13T19:20:54Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88766', 'http://dx.doi.org/10.26153/tsw/15700']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['powder variation', 'metallic powder', 'Selective Laser Melting', 'Ti6Al4V', 'microstructure', 'tensile strength']

Effects of Powder Variation on the Microstructure and Tensile Strength of Ti6Al4V Parts Fabricated by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/57ba353e-7ea4-4158-afda-6989d2c1cd41/download

University of Texas at Austin

Metallic powders are used as raw materials in the Selective Laser Melting (SLM) process. These metal powders are typically available from more than one powder vendor. Even when powders have the same nominal chemical compositions, powders produced by different companies typically result in different powder particle size distributions and morphologies. These powder differences result in different powder bed thermophysical properties, which affect how the powder melts and solidifies. This paper studies the effect of powder variation on the microstructure and tensile strength of as-built SLM Ti6Al4V parts. Ti6Al4V powders from different vendors were used to fabricate parts via SLM. Powder characteristics, such as particle size distribution, morphology, and flowability, were obtained. Powder bed densities and thermal conductivities were measured and compared. The microstructures and tensile strengths were investigated by standard metallographic and tensile testing methods. Based on the experimental results, a correlation between the powder characteristics and part properties are discussed.

null

['Akhtar, SP', 'Wright, CS', 'Youseffi, M']

2020-02-12T15:36:33Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79940', 'http://dx.doi.org/10.26153/tsw/6966']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Selective Laser Sintering

The Effects of Pre-Alloyed Steels Powder Compositions on Build Quality in Direct Metal Laser Re-Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b999c053-9596-47dd-95ca-dfde5182358c/download

null

['Mahtabi, MohammadBagher', 'Yadollahi, Aref', 'Stokes, Ryan', 'Young, Joseph', 'Doude, Haley', 'Priddy, Matthew W.', 'Bian, Linkan']

2023-01-19T16:07:00Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117247', 'http://dx.doi.org/10.26153/tsw/44128']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Build interruption', 'Additive manufacturing (AM)', 'Failure location', 'Al-Si-10Mg', 'Ti- 6Al-4V']

Effects of Process Interruption During Laser Powder Bed Fusion on Microstructural and Mechanical Properties of Fabricated Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c112176d-e2f3-4e1b-84ac-67a3a449f5d7/download

null

Despite appropriate planning, various incidents can stop the additive manufacturing (AM) process of metals and cause build interruption, such as power outage, lack of powder feedstock, and/or shielding gas to mention a few. Due to the layer-by-layer nature of fabrication, an interruption to the AM process can be resumed from the location where the stoppage occurred. However, build interruption may adversely affect the structural integrity of the fabricated parts, by causing localized failure near the interruption location. This study aims to investigate the influence of build interruption during the laser powder bed fusion (LPBF) process on the microstructural and mechanical properties of Ti-6Al-4V and Al-Si-10Mg specimens. For the Ti-6Al-4V specimens, results indicate that tensile failures near the interruption location are most likely to happen for non-heat-treated specimens in the as-built surface condition. Whereas for the Al-Si- 10Mg specimens, the failure location is more influenced by the prolonged stoppage and air exposure.

null

['Mahtabi, MohammadBagher', 'Yadollahi, Aref', 'Stokes, Ryan', 'Young, Joseph', 'Doude, Haley', 'Priddy, Matthew W.', 'Bian, Linkan']

2023-01-26T14:17:02Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117303', 'http://dx.doi.org/10.26153/tsw/44184']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Build interruption', 'Additive manufacturing', 'Failure location', 'Al-Si-10Mg', 'Ti- 6Al-4V']

Effects of Process Interruption During Laser Powder Bed Fusion on Microstructural and Mechanical Properties of Fabricated Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/44170140-71d3-435a-aa8e-706e1a139c22/download

null

Despite appropriate planning, various incidents can stop the additive manufacturing (AM) process of metals and cause build interruption, such as power outage, lack of powder feedstock, and/or shielding gas to mention a few. Due to the layer-by-layer nature of fabrication, an interruption to the AM process can be resumed from the location where the stoppage occurred. However, build interruption may adversely affect the structural integrity of the fabricated parts, by causing localized failure near the interruption location. This study aims to investigate the influence of build interruption during the laser powder bed fusion (LPBF) process on the microstructural and mechanical properties of Ti-6Al-4V and Al-Si-10Mg specimens. For the Ti-6Al-4V specimens, results indicate that tensile failures near the interruption location are most likely to happen for non-heat-treated specimens in the as-built surface condition. Whereas for the Al-Si- 10Mg specimens, the failure location is more influenced by the prolonged stoppage and air exposure.

null

['Huang, Wenpu', 'Wang, Zemin', 'Yang, Jingjing', 'Yang, Huihui', 'Zeng, Xiaoyan']

2021-11-10T23:06:23Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90204', 'http://dx.doi.org/10.26153/tsw/17125']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'process parameters', 'heat treatment', 'microstructure', 'mechanical properties']

Effects of Process Parameters and Heat Treatment on the Microstructure and Mechanical Properties of Selective Laser Melted Inconel 718

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ea24d57c-b513-4f88-8eaa-0597b9f5f924/download

University of Texas at Austin

In this study, Inconel 718 superalloy was fabricated by selective laser melting (SLM) and solution treated at 980-1230 ℃subsequently. The process window was firstly set up based on the density of the samples. Samples were fabricated using various parameters within the process window to investigate the effects of process parameters on microstructure and mechanical properties. The average dendrite arm spacing and the volume fraction of Laves phase raise along with the increasing energy input. However, no distinct difference of tensile properties was found under parameters in the process window. Interdendritic Laves phase decreases with the solution temperature, while the grain size has the opposite trend. Finally, the solution temperature was fixed at 1080 ℃to dissolve Laves phases and obtain fine grains. After solution + aging heat treatment, the tensile strengths and ductility all exceed the wrought Inconel 718.

null

['Bontha, S.', 'Brown, C. J.', 'Klingbeil, N. W.', 'Gaddam, D. R.', 'Kobryn, P. A.', 'Fraser, H. L.', 'Sears, J. W.']

2020-02-12T15:16:08Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79935', 'http://dx.doi.org/10.26153/tsw/6961']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Solidification Microstructure

Effects of Process Variables and Size Scale on Solidification Microstructure in Laser-Based Solid Freeform Fabrication of Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d2fec261-3ff6-4473-8cf8-cf59e9285fc1/download

null

['Gray IV, R. W.', 'Baird, D. G.', 'Bohn, J. H.']

2018-12-05T20:32:09Z

1997

Mechanical Engineering

doi:10.15781/T24B2XR11

http://hdl.handle.net/2152/71414

eng

1997 International Solid Freeform Fabrication Symposium

Open

['FDM', 'Thermotropic liquid crystalline polymers']

Effects of Processing Conditions on Prototypes Reinforced with TLCPs for Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1484ef81-4ea6-419e-9e3c-87dbfe6beada/download

null

Polypropylene (PP) composite strands, reinforced with thermotropic liquid crystalline polymers (TLCPs), were generated using a novel dual extrusion process which allowed for the use of a TLCP with a significantly higher melting temperature than that of the PP. Pregenerated TLCPtpp microcomposite strands were reprocessed using a second novel process to produce a wen-controned monofilament composite for use in a FDM 1600 rapid prototyping system in order to build complex geometries. Uniaxial parts were built to determine the effect of differing material compositions and processing temperatures, in order to develop an oPerating window for the optimal mechanical properties. By adjusting the lay down pattern of orientable materials, the final mechanical properties of the part could be engineered independent ofthe material. To understand the effect ofthe reprocessing steps on the pregenerated microcomposites, the final mechanical properties ofthe monofilament composite were compared with those ofthe pregenerated strands.

null

['Hrabe, Nikolas', 'Kircher, Ryan', 'Quinn, Timothy']

2021-10-07T15:02:25Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88472', 'http://dx.doi.org/10.26153/tsw/15409']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['electron beam melting', 'titanium alloy', 'Ti-6Al-4V', 'characterization', 'orientation', 'mechanical properties']

Effects of Processing on Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated using Electron Beam Melting (EBM): Orientation and Location

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2800f141-e075-4558-8353-30788794955a/download

null

Electron beam melted (EBM) titanium alloy (Ti-6Al-4V) samples were built and characterized (qualitative prior-β grain size, quantitative α lath thickness, monotonic tensile, Vickers microhardness) to determine the effect of location and orientation on microstructure and properties. Samples of vertical orientation, compared to horizontal, were found to have 30% lower elongation. Orientation within the x-y plane as well as location were found to have less than 3 % effect on mechanical properties, and it is possible a second order effect of thermal mass contributed to these results.

null

['Gong, Haijun', 'Rafi, Khalid', 'Starr, Thomas', 'Stucker, Brent']

2021-10-11T20:28:46Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88631', 'http://dx.doi.org/10.26153/tsw/15565']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'Electron Beam Melting', 'Ti-6Al-4V', 'processing parameter', 'marginal parameters', 'part defect']

The Effects of Processing Parameters on Defect Regularity in Ti-6Al-4V Parts Fabricated By Selective Laser Melting and Electron Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1961575d-60e4-4b15-bbe3-e074d2bfb298/download

University of Texas at Austin

Processing parameter has an important effect on Selective Laser Melting (SLM) and Electron Beam Melting (EBM) processes. Defects are easily formed by deviating from optimized processing parameters. This study purposely fabricated Ti-6Al-4V specimens with defects by varying process parameters from the factory default settings in both SLM and EBM equipment. Specimen’s density was measured based on the Archimedes method for estimating porosity. Microscopy of specimen’s top surface were observed to compare melt pool and overlap. “Marginal Parameters” is identified to describe the processing parameters which are capable of fabricating specimens with certain porosity. As a result, a correlation between defect regularity and marginal parameters has been established. The effect of marginal parameters on the melt pool is discussed to explain defect formation.

null

['Basak, Amrita', 'Kalaitzidou, Kyriaki', 'Das, Suman']

2021-11-02T14:35:32Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89811

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'scanning laser epitaxy', 'SLE', 'nickel-base', 'superalloys', 'CMSX-4', 'mechanical testing']

Effects of Processing Parameters on the Mechanical Properties of CMSX-4® Additively Fabricated through Scanning Laser Epitaxy (SLE)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/44239336-105c-45f8-aceb-8e03c570ee9b/download

University of Texas at Austin

The work aims to characterize the effects of processing parameters on the mechanical properties of CMSX-4® fabricated using a laser-powder bed fusion (LPBF)-based additive manufacturing (AM) process, scanning laser epitaxy (SLE). The laser power, the scan speed, and the number of repeat scans are varied in SLE. These parameters are combined to define a new measure such as the energy density. Microstructures of the samples are investigated using optical microscopy and scanning electron microscopy. Uniaxial tension tests are performed on samples in longitudinal direction and relevant data is extracted.

This work is sponsored by the Office of Naval Research through grant N00014-14-1-0658.

null

['Masoomi, Mohammad', 'Thompson, Scott M.', 'Shamsaei, Nima', 'Haghsenas, Meysam']

2021-11-08T21:56:11Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90052', 'http://dx.doi.org/10.26153/tsw/16973']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['scanning', 'residual stress', 'temperature distribution', 'laser powder bed fusion', 'L-PBF', 'Ti-6Al-4V']

Effects of Scanning Strategy on Residual Stress Formation in Additively Manufactured Ti-6Al-4V Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f285202d-ac2d-48c3-a108-c8744e82a073/download

University of Texas at Austin

Parts fabricated via directed energy additive manufacturing (AM) can experience very high, localized temperature gradients during manufacture. These temperature gradients are conducive to the formation of a complex residual stress field within such parts. In the study, a thermo-mechanical model is employed for predicting the temperature distribution and residual stress in Ti-6Al-4V parts fabricated using laser-powder bed fusion (L-PBF). The result is utilized for determining a relationship between local part temperature gradients with generated residual stress. Using this numerical model, the effects of scan patterns are investigated.

null

['Jost, Elliott', 'Miers, John', 'Robinson, Aron', 'Moore, David', 'Saldana, Christopher']

2021-11-17T23:59:16Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90362', 'http://dx.doi.org/10.26153/tsw/17283']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['spatial energy distribution', 'defects', 'fractures', 'stainless steel 316L', 'scanning electron microscopy', 'laser powder bed fusion', 'LPBF']

Effects of Spatial Energy Distribution on Defects and Fracture of LPBF 316L Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bfcdf007-1ab5-4261-b1a0-d0a8e2daa24b/download

University of Texas at Austin

Measures of energy input and spatial energy distribution during laser powder bed fusion additive manufacturing have significant implications for the build quality of parts, specifically relating to formation of internal defects during processing. In this study, scanning electron microscopy was leveraged to investigate the effects of these distributions on the mechanical performance of parts manufactured using laser powder bed fusion as seen through the fracture surfaces resulting from uniaxial tensile testing. Variation in spatial energy density is shown to manifest in differences in defect morphology and mechanical properties. Computed tomography and scanning electron microscopy inspections revealed significant evidence of porosity acting as failure mechanisms in printed parts. These results establish an improved understanding of the effects of spatial energy distributions in laser powder bed fusion on mechanical performance.

null

['Kircher, R.S.', 'Christensen, A.M.', 'Wurth, K.W.']

2021-09-28T20:27:20Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88175', 'http://dx.doi.org/10.26153/tsw/15116']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['microstructures', 'mechanical properties', 'additive manufacturing', 'Ti6Al4V alloys', 'Electron Beam Melting']

The Effects of Specimen Dimensions on the Mechanical Behavior of EBM Produced Ti6Al4V Alloys

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f2c6fe66-db6f-486d-b51e-209022d957b4/download

University of Texas at Austin

There are several published studies investigating the microstructures and mechanical properties obtained during additive manufacturing of Ti6Al4V alloys utilizing the Electron Beam Melting (EBM) technique. These studies have concentrated on conventional testing coupon sizes and configurations which allowed for a direct comparison to the properties of conventionally produced Ti6Al4V alloys. One of the many benefits of the EBM process is that it allows the manufacturer to produce components in sizes and configurations unachievable by conventional methods. It becomes important to understand and verify the microstructures and mechanical performance of these smaller components in a manufacturing environment, requiring the use of non‐conventional testing configurations. This paper presents case-studies involving the production and testing of non-standard samples and how these samples compare to conventional E8 testing coupons. Differences in mechanical performance were observed and are most likely due to the unique characteristics of EBM produced materials.

null

['Kletetzka, I.', 'Gawlikowicz, R.', 'Schmid, H.-J.']

2023-03-29T16:24:21Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117679', 'http://dx.doi.org/10.26153/tsw/44558']

eng

2022 International Solid Freeform Fabrication Symposium

Open

laser sintering

Effects of Spherical Fillers on the Processability and Mechanical Properties of PA613 and PP-Based Laser Sintering Dry Blends

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0e0bce04-badf-4597-8a3f-a34b86173668/download

null

Polymer materials filled with particles may show substantially altered mechanical properties. Therefore, it is an important aim to be able to tailor the mechanical properties of LS components by adding fillers and thus to create new application areas for additively manufactured components. In this work, the influences of spherical fillers on the processing properties and the resulting mechanical properties of laser-sintered components are investigated. For this purpose, micro glass spheres, hollow glass bubbles and mineral spheres are dry blended to the matrix polymers polyamide 613 and polypropylene with filling ratios of 20 and 40 vol%. First, relevant properties of the blends, such as powder flowability, thermal behavior and melt viscosity, are investigated. Based on the results, processing parameters are then developed for the laser sintering (LS) process and the mechanical properties of the components are investigated.

null

['Soltani-Tehrani, Arash', 'Yasin, Mohammad Salman', 'Shao, Shuai', 'Shamsaei, Nima']

2021-12-06T23:02:16Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90708', 'http://dx.doi.org/10.26153/tsw/17627']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'Ti-6Al-4V', 'stripe width', 'L-PBF', 'process parameters']

Effects of Stripe Width on the Porosity and Mechanical Performance of Additively Manufactured Ti-6Al-4V Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fb479358-df67-427b-aa0b-66ec6917b9a4/download

University of Texas at Austin

In laser powder bed fusion (L-PBF) additive manufacturing, parts are manufactured in a layer-by-layer pattern. In each layer, cross-sections can be scanned with or without partitioning by the laser, which are commonly known as “stripe” and “meander” patterns, respectively. Under the two scanning strategies, the thermal history experienced by the part can be considerably different. Accordingly, defect distribution, microstructure, and mechanical properties may be affected. In this study, two sets of Ti-6Al-4V specimens were fabricated using L-PBF: in one set, the tracks were partitioned in 5-mm stripes, while in the other set, they were partitioned at 100 mm resulting in no stripe seams in the cross-section. It was found that altering the stripe width can considerably affect the laser penetration depth, the defect content, and consequently fatigue performance. However, tensile strength was not much sensitive to changing the stripe width.

null

['Li, Jie', 'Leu, Ming C.', 'Hilmas, Gregory E.']

2021-10-19T20:15:05Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89330

eng

2015 International Solid Freeform Fabrication Symposium

Open

['temperature', 'extrusion-based additive manufacturing', 'ceramic parts', 'freeform extrusion fabrication']

Effects of Temperature on Aqueous Freeform Extrusion Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/385f5472-05bd-428e-a5f6-1769dc24836a/download

University of Texas at Austin

An experimental study was conducted to investigate the effect of temperature on ceramic parts produced by paste extrusion based additive manufacturing followed by sintering. A computer-controlled gantry system equipped with a piston extruder was used to extrude aqueous alumina paste. The system includes a temperature control subsystem that allows for freeform extrusion fabrication inside a low-temperature (<0°C) chamber. It can also be used for fabricating parts on a hot plate at ambient or higher temperatures (≥20°C). Test specimens were fabricated from aqueous aluminum pastes at -20°C in the low-temperature chamber and also on the hot plate at 40°C. The minimum angles achievable by these two processes for part fabrication, without use of support material, were compared. Also compared were the relative density and mechanical properties of the parts obtained after sintering. Microstructures were examined via scanning electron microscopy in order to obtain a deeper understanding of the effect of fabrication temperature.

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