A Numerical Approach to Model Microstructure Evolution for NiTi Shape Memory Alloy in Laser Powder Bed Fusion Additive Manufacturing

Computer simulation and prediction of the microstructure of the additively manufactured parts via laser powder bed fusion is an essential part of the computational-based design of material and components. In this work, the microstructural evolution of NiTi alloys was simulated through a multiscale multiphysics modeling approach. The model consists of two computational modules for thermal simulation and microstructural evolution. The thermal history and the melt-pool dimensions obtained from the thermal simulation were in good agreement with the experimental micrograph of the samples. The Cellular Automata method was adopted for the microstructural simulation due to the lower computational cost compared to other techniques. The introduced Cellular Automata model generated an acceptable prediction of the microstructure. The simulation results indicated columnar austenite competitive grain growth in agreement with the observations on the fabricated samples. The validated model will serve as a base for future studies toward model-informed material and part design.