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Evaluation of a thermo-mechanical model for prediction of residual stress during laser powder bed fusion of Ti-6Al-4V

Published

Author(s)

Rishi Ganeriwala, Maria Strantza, Wayne King, Bjorn Clausen, Thien Q. Phan, Lyle E. Levine, Donald W. Brown, Niel Hodge

Abstract

The build-up of residual stress in a part during laser powder bed fusion provides a significant limitation to the adoption of this process. These residuals stresses may cause a part to fail during a build or fall outside the specified tolerances after fabrication. In this work a thermo-mechanical model is used to simulate the residual stress state for Ti-6Al-4V specimens built with continuous vs. island scan strategies. An agglomeration, or lumping, approach is used to speed up the computations. A material model is developed to naturally capture the strain-rate dependence and annealing behavior of Ti-6Al-4V at elevated temperatures. Results from the thermo-mechanical simulations showed good agreement with X-ray diffraction measurements used to determine the residual elastic strains in these parts. However, the experimental measurements showed higher residual strains for the specimen built with an island scan strategy; a trend not fully captured by the simulations. Parameter studies were performed to fully understand the advantages and limitations of the current simulation methodology. Reasons for both the computational and experimental findings are discussed.
Citation
Additive Manufacturing
Issue
27

Keywords

additive manufacturing, residual stress, thermo-mechanical modeling, Ti-6Al-4V

Citation

Ganeriwala, R. , Strantza, M. , King, W. , Clausen, B. , Phan, T. , Levine, L. , Brown, D. and Hodge, N. (2019), Evaluation of a thermo-mechanical model for prediction of residual stress during laser powder bed fusion of Ti-6Al-4V, Additive Manufacturing, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926890 (Accessed December 1, 2021)
Created April 1, 2019, Updated October 12, 2021