Strength-ductility synergy in 316L austenitic stainless steel with a heterogeneous structure*

316L austenitic stainless steel (ASS) with a heterogenous structure (HS) and excellent strength-ductility synergy was fabricated by combining cold rolling (CR) with subsequent annealing. The micro-nano grain size distribution of casting microstructure provided a favorable conditions for the preparation of HS. The HS is characterized by trimodal grain size distribution of austenite, residual strain-induced alpha '-martensite, and annealing twins. The finegrain strengthening and back stress hardening play a major role in HS 316L ASS strengthening. Moreover, the favorable ductility was primarily attributed to heterogeneous deformation-induced (HDI) strain hardening of soft/hard interfaces in the HS. When the rolled steel with 70% deformation was annealed at 600 degrees C for 1 h, the yield strength (YS) of 1183 MPa with a total elongation (TEL) of 13% was obtained.