Simultaneously improved strength and ductility yet strain-hardenable 316L stainless steel by sigma phase and hetero-structuring

Abstract

In this study, we produced both homogeneous and heterogeneous-structured 316L austenitic stainless steels (SSs), each exhibiting comparable levels of yield strength (YS). Despite their similar YS, the heterogeneous-structured 316L SS exhibits a significantly higher tensile strength of ∼1 GPa compared to the homogeneous-structured 316L SS (∼832 MPa), and slightly higher fracture strain. The enhanced tensile strength and work hardening behavior in the heterogeneous-structured 316L SS were mainly attributed to the hetero-deformation induced (HDI) hardening, accelerated deformation-induced martensitic transformation (DIMT), and the presence of the nano-sized σ-phase particles. Our findings provide insights into the development of metastable heterogeneous-structured face-centered cubic (FCC) metallic materials with outstanding mechanical properties.

Keywords

• Austenitic stainless steel
• Heterostructuring
• Microstructure
• Sigma phase
• Tensile property