Ti-containing 316L stainless steels with excellent tensile properties fabricated by directed energy deposition additive manufacturing

Abstract

Additive manufacturing is used to produce complex shapes, and it has been actively investigated. In this study, 316L stainless steels with various amounts of Ti were fabricated using directed energy deposition. The addition of Ti changed the microstructure and significantly improved the tensile properties of austenitic stainless steels. The addition of Ti led to distinct microstructural evolutions, such as changes in the cellular structure, grain size and Ti-rich particle. Microstructural changes such as change in change to equiaxed cellular structure and grain refimenet were due to Ti-rich particles acting as new nucleation sites and suppressing the segregation of solute atoms. In particular, the yield strength, tensile strength, and elongation of the specimen with 2 wt% Ti were 637 MPa, 857 MPa, and 43%, respectively, which were considerably higher than those of 316L stainless steel without Ti. Therefore, the addition of Ti is a suitable strategy for improving the tensile properties of additively manufactured 316L stainless steel.