Modeling and validation of microstructure and porosity formation in Al-10Si alloy laser powder bed fusion additive manufacturing process

Laser powder bed fusion (LPBF) additive manufacturing (AM) process has been used in production of metal components in industries such as aerospace, automotive, and defense. However, challenges including porosity formation and microstructure inconsistency can compromise part performance and reliability. This study presents an adapted Cellular Automaton (CA) model for predicting microstructure evolution and hydrogen porosity formation in an Al-10 wt.%Si alloy during LPBF process. Key developments to the CA framework include the incorporation of a melt pool temperature profile, a non-equilibrium grain growth mechanism accounting for high cooling rates in AM, and a refined hydrogen pore nucleation criterion. The model captures the microstructure transition from fine equiaxed grains at the edge of the melt pool to elongated and finally large equiaxed grains at the melt pool center. Two different types of porosity morphology are simulated and validated: spherical and inter-granular. Sizes and distributions of pores and grains are compared with experimental results, showing good agreement. Future work will be aimed at extending the model to multi-layer and multi-beam configurations for broader applicability in large-scale manufacturing scenarios.