Effects of Laser Power on Melt Pool Overlap and Mechanical Properties in Selective Laser Melting 316L Stainless Steel

The control of melt pool overlap is a pivotal factor determining the quality of components fabricated by selective laser melting (SLM). This study presents an in‐depth investigation into the melt pool overlap behavior during SLM of 316L stainless steel under the influence of laser power (200–450 W), combining computational fluid dynamics simulations with experimental validation. The result reported that the effective overlap width exhibits a non‐monotonic behavior when melt pool width increases linearly with power. Meanwhile, an optimal laser power of 250 W was identified, which maximizes the effective overlap width (52.47 μm) through conduction‐dominated melting, ensuring complete remelting between adjacent tracks and promoting the formation of fine equiaxed grains. This microstructural refinement results in superior mechanical properties, including the highest peak hardness, enhanced yield ratio, and improved ductility. Moreover, higher power levels (>300 W) promote keyhole mode melting, leading to the formation of coarse cellular grains and elongated gas pores, which degrade mechanical performance. At low power (200 W), insufficient melting results in significant porosity and reduced density. This work establishes a critical linkage between laser power, melt pool dynamics, solidification behavior, and mechanical properties, providing a scientific basis for optimizing SLM processes to achieve high‐density, defect‐minimized 316L components.