Effect of boron element on microstructure and mechanical properties of 316L stainless steel manufactured by selective laser melting

Boron(B)element is often utilized to enhance mechanical properties of stainless steel due to its excellent performance. In this study, selective laser melting (SLM) was used to print 316L/B stainless steel with varying boron weight content. The effects of boron content on microstructure, nanoindentation, and mechanical properties of the printed 316L stainless steel were discussed. Fine cell dendrites and columnar crystals were found in the SLM printed stainless steel due to the rapid solidification in SLM. It was found that boron has a higher growth limiting factor in the iron system and the boron solute can provide a high component supercooling. By adding boron element to stainless steel during printing, the honeycomb and grain size after solidification are significantly reduced due to interactions between the boron element and the 316L.Tensile testing results show that the ultimate tensile strength of the SLM fabricated parts with 0.5wt% and 1wt% boron element addition can be increased significantly to 1071 MPa and 1174 MPa, respectively.