Research on the printing quality of large-layer thick laser selective melting of stainless steel powder

Selective laser melting (SLM) offers geometric flexibility, high resolution, and refined microstructures, yet its industrial adoption is limited by low productivity. Increasing layer thickness has shown potential to significantly improve build rates, but a systematic understanding of the interrelationships among layer thickness, powder size, process parameters, microstructural evolution, and mechanical properties remains insufficient. This study systematically evaluates 316L stainless steel processed using powder sizes of 15–53 μm and 48–105 μm under layer thicknesses of 50, 70, 90, and 110 μm. Results show relative densities exceeding 99% for layers up to 90 μm. While coarse powder at 50 μm exhibited comparable strength and slightly higher elongation than fine powder, increased lack-of-fusion defects at higher layer thicknesses led to progressive mechanical deterioration. Notably, fine powder samples at 70 μm achieved a yield strength of 592 MPa, tensile strength of 730 MPa, elongation of 60.5%, and a build rate of 7.3 mm 3 /s, demonstrating balanced properties and approximately triple the productivity compared to standard 30 μm layers. These findings suggest that a 70 μm layer thickness provides a viable trade-off between mechanical performance and build efficiency for applications not requiring high surface quality.