Laser Powder Bed Fusion (LPBF) is an extensively used Additive Manufacturing (AM) method that can build metal parts with complicated geometric designs. However, because of the rapid solidification conditions and the layer-by-layer building, its application is challenged by the products’ poor surface quality and limited mechanical properties. Laser rescanning process is often used as a refinement method during LPBF to improve the quality of products. In this study, the grain structure formation during laser rescanning process of LPBF is modelled in 3D by a Cellular Automaton (CA)-based microstructure model coupled with Finite Element Analysis (FEA). The coupled model considers different nucleation mechanisms, including epitxial growth, which are applicable to rapid solidification in melt pool. The model is adapted to reproduce grain structure of Al-Si alloy manufactured by LPBF with laser rescanning strategy. The effects of laser remelting on the characteristics of grain structure, i.e., grain size, aspect ratio and orientation are evaluated. The mechanisms that enable unique grain structure e.g., refinement, are discussed.

Moderated by: Hani Henein / Mark Jolly