Ti-Modified Additively Manufactured 316l Stainless Steel: Microstructural Refinement and Superior Mechanical Properties

Abstract

This study investigates the effect of Ti modification on the microstructure and mechanical properties of 316L stainless steel fabricated by selective laser melting (SLM), aiming to enhance its mechanical strength for structural applications. The incorporation of Ti led to a pronounced refinement in microstructure, primarily due to the formation of Ti(C,N,O) nanoparticles that served as heterogeneous nucleation sites. As a result, the yield strength of the Ti-modified SLM 316L increased to 637 ± 3 MPa, and the ultimate tensile strength reached 837 ± 5 MPa, representing enhancements of 11.56% and 15.77%, respectively, over the unmodified SLM 316L. Notably, the total elongation remained at a high level, indicating a balance between strength and ductility. The enhanced mechanical properties are primarily attributed to the combined effects of grain boundary strengthening and Orowan strengthening from the Ti(C,N,O) nanoparticles.

Keywords: 316L stainless steel, Selective laser melting, Heterogeneous nucleation, grain refinement