Supreme tensile properties in precipitation-hardened 316L stainless steel fabricated through powder cold-consolidation and annealing

Abstract

One of the key goals of processing 316L stainless steel by powder metallurgy (PM) techniques is to achieve industrial-viable tensile properties without structural defects like poor densification, undesired phase transitions, and oxidation during high-temperature sintering. To address this, this study adopts high-pressure torsion to fabricate a fully dense structure at ambient temperature through cold consolidation. The samples fabricated by the present PM-based technique exhibits considerably enhanced tensile properties compared to counterparts processed by conventional PM techniques, with a remarkable yield strength of 1 GPa and total elongation of 46%. Additionally, the segregation of certain elements during subsequent annealing results in a unique microstructure with nano-scale sigma precipitates which induces dislocation pile-up, leading to improved yield strength and retarded dislocation motion. The results indicate that the present PM-based route is an applicable technique to achieve the strength-ductility synergy in 316L stainless steel.