Additive Manufacturing: Alloy Design to Develop New Feedstock Materials III: On-Demand Oral Presentations
Sponsored by: TMS Alloy Phases Committee
Program Organizers: Aurelien Perron, Lawrence Livermore National Laboratory; Joseph McKeown, Lawrence Livermore National Laboratory; Manyalibo Matthews, Lawrence Livermore National Laboratory; Peter Hosemann, University of California, Berkeley; Christian Leinenbach, Empa, Swiss Federal Laboratories for Materials Science and Technology
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 1
Location: MS&T On Demand
Spherical Micro/Macro Indentation Stress-strain Curves for Additive Manufacturing Materials Design: Jordan Weaver1; Patxi Fernandex-Zelaia2; Houshang Yin3; Xiaoyuan Lou3; 1National Institute of Standards and Technology; 2Oak Ridge National Laboratory; 3Auburn University
High throughput experiments are needed for materials design in additive manufacturing. While combinatorial methods for materials design and optimization can produce samples with varying chemical compositions and microstructures, complimentary rapid mechanical test methods are lacking. This work focuses on instrumented spherical micro and macro indentation, which captures the elastic loading, elastic-plastic transition, and plastic flow; and how it can be used as a rapid surrogate test for uniaxial stress-strain curves. Indentation stress-strain curves will be presented on two conventional additive alloys (LPBF 316L stainless steel and EBM Haynes 282) with distinct microstructure variations (porosity and grain morphology, respectively) and compared against their uniaxial stress-strain curves. Outstanding measurement science issues that limit the use of surrogate indentation methods will be discussed.
Development of Al-Ce Alloys for Additive Manufacturing Using the CALPHAD Method: Emily Moore1; Zachary Sims1; Hunter Henderson1; Orlando Rios2; Scott McCall1; David Weiss3; Aurélien Perron1; 1Lawrence Livermore National Laboratory; 2UT Knoxville; 3Eck Industries
The addition of rare-earth elements (REE), specifically cerium and lanthanum is of interest to improve the mining economics of Nd, Pr, Sm, etc., which are widely used in clean energy technology. Thermochemical modeling using the CALPHAD method (CALculation of PHAse Diagrams) aids in designing alloys for additive manufacturing by predicting the phase-behavior of multi-component systems. A thermodynamic database to investigate Al-Ce alloys has been developed and include the following elements, respectively : Al-Ce-Cu-Fe-La-Mg-Mn-Ni-Si-Zn-Zr. The model is applied to design new alloys with within specified composition ranges and include relevant phases that are empirically known to provide strengthening properties. Prepared by LLNL under Contract DE-AC52-07NA27344. Research supported by CMI, an Energy Innovation Hub funded by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. LLNL-ABS-820845
Solidification Cracking in Binary Al-Cu Alloys (1.5, 3.0, 4.5, 6.0, and 10 wt.% Cu) Additively Manufactured by Laser Powder Bed Fusion: Keegan Muller1; Thinh Huynh1; Holden Hyer1; Sharon Park1; Le Zhou2; Jeongmin Woo1; Abhishek Mehta1; Brandon McWilliams3; Kyu Cho3; Yongho Sohn1; 1University of Central Florida; 2Marquette University; 3DEVCOM US Army Research Laboratory
Understanding of solidification cracking and its composition dependence are crucial in designing alloys that are suitable for laser powder bed fusion (LPBF). In this study, the crack density of Al-Cu binary alloys (1.5, 3.0, 4.5, 6.0, and 10 wt.% Cu), produced by LPBF from gas atomized powders, were determined by metallography, and examined with respect to Kou’s cracking susceptibility index, |dT/d(fs)1/2|, derived from the Scheil-Gulliver equation. Maximum crack density was experimentally observed for alloys with higher solute content than that predicted by cracking susceptibility model (i.e., no diffusion in solid and equilibrium partition coefficient). Presence of solid-state diffusion and/or variation in partition coefficient on cracking susceptibility index, based on Kurz and Fisher’s modified Scheil-Gulliver equation, were examined to deduce their respective influence on the composition-dependence and magnitude of LPBF solidification cracking index. Partition coefficients appropriate for LPBF solidification were estimated based on diffusion coefficients available in literature for Al-Cu alloys.
Additive Manufacturing Feasibility Investigation Using Single Track Study for the Fabrication of Borated Austenitic Stainless Steels via Laser Powder Bed Fusion: Abhishek Mehta1; Devin Imholte2; Nicolas Woolstenhulme2; Daniel Wachs2; Yongho Sohn1; 1University of Central Florida; 2Idaho National Laboratory
Borated austenitic stainless steels can be used in nuclear applications for criticality control in fuel storage and reactivity control and flux adjustment in reactors. Single laser scans (SLS) were performed on the bulk S30465 and S30467 alloys to explore the feasibility to fabricate them using laser powder bed fusion (LPBF). SLS were performed as functions of laser power and scan speed. In S30465, melt-pools developed keyhole porosities at 200 W for low scan speeds (≤ 500 mm/s), but no flaws were observed at 350 W. In S30467, melt-pools developed keyhole porosities at 200 W for low scan speeds (≤ 300 mm/s), and a significant cracking was observed at 350 W. Dense and defect free solidification occurred for both alloys with the laser power of 200 W using intermediate scan speeds (700 – 1100 mm/s). Microstructure of the solidified melt-pool consisted of ultra-fine γ + (Cr,Fe)2B eutectic in continuous γ-phase matrix.
Grain Boundary Engineering of 316L Stainless Steel via Laser Powder Bed Fusion: Matteo Seita1; Shubo Gao1; 1Nanyang Technological University
Applying conventional grain boundary engineering (GBE) to parts produced using near-net-shape manufacturing processes—including additive manufacturing (AM)—is challenging due to the copious mechanical strain involved. In this study, we present an alternative route to GBE of as-built AM alloys which requires no mechanical deformation. Focusing on laser powder bed fusion of 316L stainless steel, we find that the propensity of the alloy to recrystallize mainly depends on the solidification microstructure—including the cell size and the amount of solute that decorates their interfaces—which may be controlled by tuning the process parameters. By choosing the proper laser scanning strategy, we demonstrate the capability of triggering recrystallisation site-specifically and produce “microstructure architectures” consisting of controlled grain boundary character distributions. The resulting alloys exhibit non-conventional mechanical properties and showcase the additional opportunity offered by AM to design superior materials with complex microstructures.