Influence mechanism of selective laser melting process parameters on melt pool evolution and grain growth of Inconel 625

This study establishes a multi-physics field coupling model integrating the Discrete Element Method (DEM), Computational Fluid Dynamics (CFD), and Cellular Automaton (CA) to systematically simulate the melt pool evolution and grain growth behaviors of Inconel 625 alloy during the multi-layer and multi-pass selective laser melting (SLM) process. The effects of process parameters, including spot diameter, scanning spacing, and inter-layer scanning strategy, on the melt pool morphology, temperature field, flow field, and grain structure are investigated. The results indicate that an increase in spot diameter leads to a widened melt pool, reduced depth, increased grain size, and weakened orientation. Excessively large scanning spacing causes unfusion defects, while overly small spacing results in thermal accumulation and spattering. The inter-layer scanning rotation angle (0°, 90°, 180°) significantly affects grain orientation and texture strength: 0° scanning tends to form strong textures and coarse columnar grains, whereas 90° and 180° scanning contribute to grain refinement and reduced anisotropy. Experimental validation confirms the reliability of the simulation results, providing a theoretical basis for SLM process parameter optimization and microstructural regulation.