Three-dimensional modeling of the microstructure evolution during metal additive manufacturing

Prediction of microstructures of additive manufactured materials is a significant research focus to face the challenge of producing tailored components. In this work, a three-dimensional numerical model is developed to evaluate fundamentals of grain structure evolution during metal additive manufacturing. Cellular automata and finite difference methods are coupled to predict the grain structure, depending on a transient temperature field during the additive manufacturing process. Selective laser melting process that makes use of a high energy density laser beam to produce parts of highly complex shape by melting of metallic powder is examined. The predicted grain structure is consistent with the experimental data. The results obtained show that specific solidification conditions in selective laser melting and grain selection associated with competitive nature of grain growth promote the development of coarse columnar grains with the most favorable growth direction misaligned with the build direction. This results in morphological and crystallographic texture. (C) 2017 Elsevier B.V. All rights reserved.