Abstract

For additive manufacturing (AM), the certification and qualification paradigm needs to evolve as there exists no “ASTM-type” additive manufacturing certified process or AM-material produced specifications.  Even for small changes in starting feed material (powder or wire), component geometry, build process variables, and post-build thermo-mechanical processing, the qualification cycle can be complicated leading to long implementation times for even small changes. This is due in large part to the fact that we are not able to predict and control processing-structure-property-performance (PSPP) relationships.  Metallic-component certification requirements have been documented elsewhere but generally involve meeting engineering and physics requirements tied to the functional requirements of the engineering component and finally process and product qualification.  Key microstructural parameters and defects will need to be quantified to establish minimum performance requirements.

Certification requirements generally involve meeting engineering and physics requirements tied to the functional requirements of the engineering component and finally process and product qualification. In this presentation, the results of a study quantifying the constitutive behavior of Tantalum (Ta) fabricated by Laser-Powder-Bed additive manufacturing(AM) using an EOS platform and by wire-fed E-Beam Sciaky machine is presented.  The microstructure and texture of the AM-Ta is detailed.  The mechanical behavior of the AM Ta build was characterized using compression testing as a function of strain rate, temperature and orientation relative to the build direction. The dynamic damage evolution and failure response of the AM-Ta material, as well as wrought Ta, was probed using flyer-plate impact driven spallation experiments instrumented with PDV velocimetry.  The damage evolution as a function of orientation and peak shock stress was characterized using optical metallography and electron-back-scatter diffraction (EBSD).

Biography

GEORGE T. (Rusty) GRAY III is a Laboratory Fellow and staff member in the dynamic properties and constitutive modeling team within the Materials Science Division of Los Alamos National Laboratory (LANL). He received his Ph.D. in materials science in 1981 from Carnegie-Mellon University.  He came to LANL following a three-year visiting scholar position at the Technical University of Hamburg-Harburg in Hamburg, Germany. As a staff member (1985-1987) and later team leader (1987-2003 & 2014-present) in the Dynamic Materials Properties and Constitutive Modeling Section within the Structure / Property Relations Group (MST-8) at LANL, he has directed a research team working on investigations of the dynamic response of materials. He conducts fundamental, applied, and focused programmatic research on materials and structures, in particular in response to high-strain-rate and shock deformation. His research is focused on experimental and modeling studies of substructure evolution and mechanical response of materials. These constitutive and damage models are utilized in engineering computer codes to support large-scale finite element modeling simulations of structures ranging from national defense (DOE, DoD, DARPA), industry (GM, Ford, Chrysler, and Bettis), foreign object damage, and manufacturing. He is a Life Member of Clare Hall, University of Cambridge in the UK where he was on sabbatical in the summer of 1998. He co-chaired the Physical Metallurgy Gordon Conference in 2000. He is a Fellow of the American Physical Society (APS), a Fellow of ASM International (ASM), and a Fellow of the Minerals, Metals, and Materials Society (TMS). He is a member of APS, ASM, TMS, and serves on the International Scientific Advisory Board of the European DYMAT Association. In 2010, he served as the president of the Minerals, Metals, and Materials Society. Starting in 2012 he became the chair of the Acta Materialia Board of Governors that oversees the publication of the journals Acta Materialia, Scripta Materialia, Acta Biomaterialia, and Materialia. He has authored or co-authored over 435 technical publications. In 2017, he was elected to the National Academy of Engineering (NAE).