Microstructure programming and defect control in selective laser melted 316L stainless steel lattices

Selective laser melting (SLM) unlocks lightweight potential in 316L stainless steel lattice structures (LSs), yet internal defects and performance heterogeneity persist. This study employs response surface methodology (RSM) and analysis of variance (ANOVA) to establish quantitative relationship between geometric (forming angle FA, rod diameter RD) and processing parameters (laser power LP, scanning speed SS, hatch spacing HS) on strut quality, and identifies FA and RD as dominant controllers of mass deviation superseding laser parameters. Results reveal a microstructure programming mechanism where FA governs residual stress states and generates in situ functionally graded microstructures through thermocapillary-driven directional solidification, while RD controls solidification morphology and defect type, triggering a transition from equiaxed to columnar through thermal mass-controlled cooling. Furthermore, crystallographic texture becomes controllable where high FA induces texture alignment along the building direction, while large RD enhances texture strength through competitive grain growth. The findings provide an approach for LS fabrication, transitioning from coupled compromise to precision microstructure programming, advancing applications in biomedical implants and aerospace components.