Article
Engineering, Manufacturing
O. Dolev, S. Osovski, A. Shirizly
Summary: The tensile behavior and fracture toughness of a hybrid Ti-6Al-4V alloy were examined, showing good properties without a preference for crack growth. The hybrid manufacturing approach studied here expands the current limitations of large-scale critical components and allows for higher throughput.
ADDITIVE MANUFACTURING
(2021)
Article
Materials Science, Coatings & Films
Muhannad Ahmed Obeidi, Andre Mussatto, Merve Nur Dogu, Sithara P. Sreenilayam, Eanna McCarthy, Inam Ul Ahad, Shane Keaveney, Dermot Brabazon
Summary: The poor surface quality of Additively Manufactured (AM) components can increase the overall cost and lead time of high-performance components. In this study, Ti-6Al-4V Grade 23 ELI parts manufactured through L-PBF process were treated with CO2 laser polishing to reduce the average surface roughness and peak-to-valley distance significantly.
SURFACE & COATINGS TECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
Lu Yang, Saranarayanan Ramachandran, Axieh Bagasol, Qiyu Guan, Weiguang Wang, David J. Browne, Denis Dowling, Wajira Mirihanage
Summary: Laser powder bed fusion (LPBF) technology enables the production of metallic components without conventional design and manufacturing constraints. By reconstructing the as-solidified microstructure across the LPBF build volume, the initial solidification microstructure of Ti-6Al-4V alloy can be revealed, providing insights into the early stages of solidification. This approach also has the potential to explore solidification microstructure and defect formation in titanium alloys during additive manufacturing.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
William J. Davids, Hansheng Chen, Keita Nomoto, Hao Wang, Sudarsanam Babu, Sophie Primig, Xiaozhou Liao, Andrew Breen, Simon P. Ringer
Summary: The study reveals significant variations in beta phase fraction within a given build and categorizes high-temperature beta phase into two types based on their formation temperature, providing new insights into the phase transformation pathway during additive manufacturing.
Article
Materials Science, Multidisciplinary
J. Chen, D. Fabijanic, M. Brandt, Y. Zhao, S. B. Ren, W. Xu
Summary: This study demonstrates the development of a near-equiaxed α microstructure in situ via dynamic globularization in the as-built state of LPBF Ti-6Al-4V for the first time. The globularization process during LPBF is governed by mechanisms such as sub-grain boundary formation, boundary splitting, thermal grooving, lamellar termination migration and epitaxial growth. These findings provide new knowledge towards a holistic microstructural control strategy in additively manufactured Ti-6Al-4V.
Article
Nanoscience & Nanotechnology
Haiyang Fan, Chengcheng Wang, Yujia Tian, Kun Zhou, Shoufeng Yang
Summary: This study investigated the feasibility of using L-PBF to fabricate two Ti-6Al-4V-based bimetals, Ti-6Al-4V/γ-TiAl and Ti-6Al-4V/Ti-6242, which may have great potential for the future manufacturing of aerospace components. The bimetal Ti-6Al-4V/γ-TiAl was unsuccessfully built due to the intrinsic cold cracking of γ-TiAl processed by L-PBF. In comparison, the bimetal Ti-6Al-4V/Ti-6242 was successfully manufactured by L-PBF with a solid and defect-free interface.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Patiparn Ninpetch, Pruet Kowitwarangkul, Prasert Chalermkarnnon, Patcharapit Promoppatum, Piyapat Chuchuay, Phadungsak Rattanadecho
Summary: This study explored and predicted the distortion of Ti-6Al-4V components manufactured using the L-PBF process through numerical modeling. The results showed good agreement between the numerical model and experimental data, and identified that the difference in stiffness between the tibial tray and support structure resulted in significant distortion. Additionally, component size and support-structure design were found to play an important role in distortion reduction.
Article
Engineering, Manufacturing
Mohammadreza Asherloo, Ziheng Wu, Mike Heim, Dave Nelson, Muktesh Paliwal, Anthony D. Rollett, Amir Mostafaei
Summary: L-PBF processed HDH Ti-6Al-4V alloy achieves near-full density with a particle size distribution of 50-120 μm. Mechanical grinding reduces surface roughness and improves fatigue strength. Fracture behavior shows a combination of brittle and ductile fractures.
ADDITIVE MANUFACTURING
(2022)
Article
Engineering, Manufacturing
Liesbet Deconinck, Maria T. Villa Vidaller, Elena Bernardo Quejido, Eric A. Jaegle, Tom Depover, Kim Verbeken
Summary: This study investigates the hydrogen embrittlement of Ti-6Al-4V titanium alloy processed by different manufacturing methods. The susceptibility to hydrogen embrittlement is determined by the microstructure. In-situ electrochemical hydrogen charging tests and various analytical techniques are used to examine the mechanical characteristics and microstructural interactions with hydrogen. The presence of the beta phase increases the hydrogen uptake capacity and enhances the susceptibility to hydrogen embrittlement.
ADDITIVE MANUFACTURING
(2023)
Article
Chemistry, Physical
K. Yang, X. Yang, Z. L. Zhang, T. T. Zhu, J. Li, X. S. Xiao, Y. X. Liang, B. Jian, C. Li, S. N. Luo
Summary: The spall damage of Ti-6Al-4V alloy fabricated via laser powder bed fusion (LPBF) was investigated through plate impact in the build direction (BD) and the transverse direction (TD), focusing on its mechanisms and microstructure effects. Comparative analysis was performed on conventionally hot-rolled Ti-6Al-4V alloys processed with annealing and quenching. Results showed that the spall strength and Hugoniot elastic limit (HEL) of LPBF-fabricated samples were higher in the TD loading than in the BD loading. The LPBF-fabricated alloy exhibited a lower HEL but similar spall strength compared to conventionally fabricated alloys. The anisotropy in mechanical properties and damage was attributed to columnar prior beta grains, morphological, and crystallographic texture of martensite laths.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Nanoscience & Nanotechnology
Polina Metalnikov, Dan Eliezer, Guy Ben-Hamu
Summary: This study found that the susceptibility to hydrogen embrittlement (HE) differs significantly between Ti?6Al?4V alloys prepared by selective laser melting (SLM) and electron beam melting (EBM). The degradation of SLM Ti?6Al?4V in a hydrogen containing environment is likely to occur through hydride formation and cleavage mechanism, while Ti?6Al?4V prepared by EBM is more likely to degrade through hydrogen enhanced localized plasticity (HELP) mechanism.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Mechanical
M. Tarik Hasib, Halsey E. Ostergaard, Xiaopeng Li, Jamie J. Kruzic
Summary: The study found that the fatigue crack growth rates of Ti-6Al-4V material are influenced by build orientation and post heat treatments, while texture and build orientation have minimal impact on slow crack growth rates and fatigue thresholds. The definition of fatigue thresholds lies in the ability to transfer slip from one α' / α laths to another, with some effect of crack closure induced by roughness. The transition away from microstructure sensitive fatigue crack growth occurred when the packet/colony size equaled the cyclic plastic zone size.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Materials Science, Multidisciplinary
J. Chen, D. Fabijanic, M. Brandt, W. Xu
Summary: This study demonstrates the achievement of equiaxed prior-beta grain structure in situ in LPBF Ti-6Al-4V via epitaxial recrystallization mediated by alpha -+ beta phase transformation taking place in the rapid heating stage of LPBF thermal cycling. The hypothesis is strongly supported by experimental evidence and unveils the critical role of LPBF thermal cycling and associated phase transformation in microstructure evolution.
MATERIALS CHARACTERIZATION
(2023)
Article
Engineering, Manufacturing
Ziheng Wu, Mohammadreza Asherloo, Runbo Jiang, Melody H. Delpazir, Nihal Sivakumar, Muktesh Paliwal, Joe Capone, Benjamin Gould, Anthony Rollett, Amir Mostafaei
Summary: Laser powder bed fusion is a dominant process in the additive manufacturing industry, and the study found that hydride-dehydride Ti-6Al-4 V powder can reduce costs and achieve nearly fully dense components. By optimizing process parameters, the in-part porosity can be controlled. Two porosity formation mechanisms were proposed and attributed to the unique characteristics of the HDH powder bed.
ADDITIVE MANUFACTURING
(2021)
Article
Engineering, Manufacturing
M. Strantza, R. K. Ganeriwala, B. Clausen, T. Q. Phan, L. E. Levine, D. C. Pagan, J. P. C. Ruff, W. E. King, N. S. Johnson, R. M. Martinez, V Anghel, G. Rafailov, D. W. Brown
Summary: This study investigates the effect of laser scan strategy on the three-dimensional residual stress state of L-PBF metallic components. High-energy X-ray diffraction was used to measure residual stress in Ti-6Al-4V bridge components built with different scanning patterns. The observed residual stresses were found to be large, around 1/2 to 3/4 of the yield strength, with higher stresses near the edges of components built with island scan strategies.
ADDITIVE MANUFACTURING
(2021)
Article
Acoustics
Hualong Du, Omid Yousefian, Timothy Horn, Marie Muller
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
(2020)
Article
Engineering, Manufacturing
Christopher Rock, Rashmi Vadlakonda, Sullivan Figurskey, Christopher Ledford, Harvey West, Victoria Miller, Mark Pankow, Karen E. Daniels, Tim Horn
ADDITIVE MANUFACTURING
(2020)
Article
Engineering, Manufacturing
Christopher Ledford, Mouda Tung, Chris Rock, Timothy Horn
ADDITIVE MANUFACTURING
(2020)
Article
Materials Science, Ceramics
Yujun Jia, Shashvat Tejaskumar Mehta, Ryan Li, Md Atiqur Rahman Chowdhury, Timothy Horn, Chengying Xu
Summary: This research evaluates the feasibility of using electron beam melting (EBM) for the additive manufacturing of ultra-high temperature ceramics (UHTCs) and investigates the microstructures of the fabricated materials under different processing conditions. A mathematical model was developed to optimize the processing parameters and the simulation results were compared with experimental observations. The potential for additive manufacturing of UHTCs with complex geometries using EBM technique is demonstrated in this study.
CERAMICS INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Christopher Rock, Christopher Ledford, Matias Garcia-Avila, Harvey West, Victoria M. Miller, Mark Pankow, Ryan Dehoff, Tim Horn
Summary: By consecutively using gas-atomized nickel alloy ATI 718 (TM) powders for ten builds in a LPBF additive manufacturing process, changes in particle size distribution, morphology, and oxygen content were observed. Repeated use resulted in unusual particle morphologies and the presence of aluminum oxide on particle surfaces, contributing to increased oxygen content in the recycled feedstock powder.
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
(2021)
Article
Chemistry, Physical
Prithwish Tarafder, Christopher Rock, Timothy Horn
Summary: This study investigates the mechanical properties of unalloyed copper processed by electron beam powder bed fusion, finding that sample orientation has a significant impact on both strength and elongation, primarily influenced by the interplay between epitaxial columnar grain morphology and dislocation movement during the tensile test.
Article
Materials Science, Multidisciplinary
Elizabeth A. I. Ellis, Michael A. Sprayberry, Christopher Ledford, Jameson P. Hankwitz, Michael M. Kirka, Chris D. Rock, Timothy J. Horn, Yutai Katoh, Ryan R. Dehoff
Summary: Additive manufacturing (AM) offers a new design paradigm for engineering materials, especially for difficult to process materials like tungsten. By using electron beam powder bed fusion (EB-PBF) technology, the influence of process parameters on defect density in pure tungsten was studied, and a cracking mechanism for tungsten and suggestions for suppression of cracks were proposed.
JOURNAL OF NUCLEAR MATERIALS
(2021)
Article
Chemistry, Physical
Jameson P. Hankwitz, Christopher Ledford, Christopher Rock, Scott O'Dell, Timothy J. Horn
Summary: Niobium-based tungsten alloys are ideal for high-temperature structural applications, but are limited by their room-temperature ductility and fabricability. Powder bed fusion additive manufacturing can help process alloys with limited ductility, with post-processing heat treatments required to improve mechanical properties.
Article
Materials Science, Multidisciplinary
Christopher Rock, Prithwish Tarafder, Lawrence Ives, Timothy Horn
Summary: Copper powder was deposited onto stainless steel substrate using electron beam powder bed fusion additive manufacturing to create bimetallic structures with consistent strength properties. The interface region of the bimetallic structures contained liquid phase separated copper and iron + chromium rich regions, transitioning from an iron rich mixture to a copper rich mixture within a few additive manufacturing layers.
MATERIALS & DESIGN
(2021)
Article
Materials Science, Multidisciplinary
Timothy Horn, Christopher Rock, Djamel Kaoumi, Iver Anderson, Emma White, Tim Prost, Joel Rieken, Sourabh Saptarshi, Ryan Schoell, Matt DeJong, Sarah Timmins, Jennifer Forrester, Saul Lapidus, Ralph Napolitano, Dalong Zhang, Jens Darsell
Summary: Mechanically alloyed Fe-based alloys with oxide dispersion strengthening have faced challenges in the marketplace due to complex and unreliable processing. However, research on alternate processing routes for oxide dispersion strengthened steels has been motivated by their desirable properties. This study explores the use of Fe GARS powders in laser powder bed fusion additive manufacturing and evaluates the formation of oxide dispersoids in the liquid melt pool.
MATERIALS & DESIGN
(2022)
Article
Materials Science, Multidisciplinary
Sourabh Saptarshi, Matthew DeJong, Christopher Rock, Iver Anderson, Ralph Napolitano, Jennifer Forrester, Saul Lapidus, Djamel Kaoumi, Timothy Horn
Summary: Laser powder bed fusion (LPBF) additive manufacturing is a promising method for fabricating oxide dispersion strengthened (ODS) steels. Gas atomization reaction synthesis (GARS) was used to produce 14YWT ferritic steel powders, which were then consolidated using LPBF. The resulting materials exhibited high density and uniform distribution of Ti2Y2O7 pyrochlore dispersoids. By using GARS powders, the need for mechanical alloying was eliminated, and preliminary mechanical tests showed high ultimate tensile and yield strength.
Article
Materials Science, Multidisciplinary
D. Zhang, J. T. Darsell, J. Wang, X. Ma, G. J. Grant, I. E. Anderson, J. R. Rieken, D. J. Edwards, W. Setyawan, T. J. Horn, G. R. Odette
Summary: Oxide dispersion strengthened (ODS) steels are promising structural materials for future fusion reactors. They have high-density nano-oxides that provide radiation resistance and high-temperature creep strength. Helium management is also enabled by trapping small helium bubbles near the nano-oxides. However, the conventional manufacturing route faces challenges with scalability and cost. The gas atomization reaction synthesis (GARS) method, combined with friction-based processing, shows potential in improving the nano-oxide characteristics.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Denysse Gonzalez Ovalle, Christopher Rock, Christopher Winkler, Devin Hartshorn, Chris Barr, Tristan Cullom, Prithwish Tarafder, Tim Prost, Emma White, Iver Anderson, Tim Horn
Summary: A micro-alloyed copper powder, Cu-0.3Zr-0.15Ag wt%, was produced to reduce the oxygen content on the surface of the powder particles. Solid test articles were fabricated using both as-received powders and intentionally oxidized powders. The addition of zirconium resulted in the formation of discontinuous ZrO2 structures in the metallographic cross-sections.
MATERIALS CHARACTERIZATION
(2023)
Article
Materials Science, Multidisciplinary
Haozhi Zhang, Paul R. Carriere, Emmanuel D. Amoako, Chris D. Rock, Seiji U. Thielk, Colin G. Fletcher, Timothy J. Horn
Summary: This study explores the process, structure, and property relationship of pure tungsten fabricated by electron beam powder bed fusion (EB-PBF). The results show high density and reduced cracking, with a microstructure containing equiaxed grains and subgrains. Flexural testing demonstrated high ductility at 900°C.
Proceedings Paper
Nuclear Science & Technology
Lawrence Ives, Thuc Bui, Thomas Habermann, George Collins, David Marsden, Jeffrey Neilson, Tim Horn, Chris Rock
Summary: This paper presents a new series of MW-class RF loads that can dissipate power levels exceeding 1.5 MW at frequencies from 28 GHz to 180 GHz. The loads are designed to reflect less than 0.25% of the input power and operate continuously (CW). Stainless-steel and anodized aluminum versions were developed, with the stainless steel version meeting requirements for nuclear facilities and the aluminum version capable of power levels exceeding 2 MW CW, while also being lighter and less expensive.
21ST JOINT WORKSHOP ON ELECTRON CYCLOTRON EMISSION AND ELECTRON CYCLOTRON RESONANCE HEATING, EC21
(2023)
