Multiscale simulations of metal additive manufacturing processes

Much of the latent promise of metal additive manufacturing (AM) rests in the potential for controlled creation of spatially tailored microstructures, designed to optimize key build-scale properties through systematic variation across a build. Component optimization possibilities and performance potential expand enormously when this becomes possible. However, the extreme conditions created by AM energy sources and the nature of alloy solidification under such conditions are not adequately understood. Modeling and simulation tools capable of quantitatively predicting AM microstructural outputs would enable a major leap forward.

A new study by LLNL and Oak Ridge National Laboratory researchers demonstrated through experimental validation that a multiscale simulation framework coupling thermodynamic models, microstructure-scale phase field simulations, and laser-track-scale multiphysics simulations could quantitatively predict tailored microstructure formation in a laser-processed titanium-niobium alloy. Through extensive large-scale simulations and analysis of detailed microstructural predictions over a broad range of conditions, the research team uncovered scaling laws for characteristic microstructural features that permit systematic and straightforward generalization of their findings to a wide range of materials. Further, the study highlighted the central importance of the alloy freezing range, which provides the basis of a generalized strategy for optimizing spatial control of microstructure during AM. The team noted that the type of computational capability developed through this project provides an efficient way to pursue AM process optimization for existing alloys and to design, test, and explore new alloys and processing approaches.

This research was highlighted on the inside cover of Materials Today. The project was funded by the Laboratory Directed Research and Development Program (18-SI-003).

[J. Berry, A. Perron, J.-L. Fattebert, J.D. Roehling, B. Vrancken, T.T. Roehling, D.L. Rosas, J.A. Turner, S.A. Khairallah, J.T. McKeown, and M.J. Matthews, Toward multiscale simulations of tailored microstructure formation in metal additive manufacturing, Materials Today (2021), doi: 10.1016/j.mattod.2021.09.024.]