Residual stresses and microstructure within Allvac 718Plus laser powder bed fusion bars

Thomas R. Watkins, Kinga A. Unocic, Alonso Peralta, Mustafa Megahed, Jeffrey R. Bunn, Chris M. Fancher, Christopher R. D'Elia, Michael R. Hill, James F. Neumann

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The residual stresses within Allvac 718Plus bars built using LBPF with different laser powers, speeds and table displacements were measured using diffraction and mechanical methods and modelled with the baseplate attached and then removed. The residual stress profiles within the bars from the top surface down through the bulk were all quite similar, becoming less tensile due to a strain hardening mechanism. Table displacement has the greatest impact on residual stress, decreasing with increasing displacement/powder layer thickness. There was good agreement amongst the modeling and measurements. The microstructures were examined and varied slightly with energy density with higher densities having larger grains and enhanced post solidification diffusion. Energy density had minimal impact on the residuals stresses within the parameters to produce dense material.

Original languageEnglish
Article number102334
JournalAdditive Manufacturing
Volume47
DOIs
StatePublished - Nov 2021

Funding

At ORNL, D.W. Coffey, T.M. Lowe, T.S. Geer, D. Leonard and K. Cooley assisted with some of the experimental work. Dr.’s J. Peng and D. Shin provided critical insights. Dr.’s E. Cakmak and A. Sabau provided helpful comments on the manuscript. Research was sponsored by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office , under contract DE-AC05-00OR22725 with UT-Battelle LLC. Research at the 2nd Generation Neutron Residual Stress Mapping Facility at the High Flux Isotope Reactor was partially sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy . Microscopy research was performed using FEI Talos F200X S/TEM instrumentation provided by the Department of Energy, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Keywords

  • Additive manufacturing
  • Curvature
  • Microstructure
  • Modelling
  • Neutron & x-ray diffraction

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