Overcoming the strength-ductility trade-off in metastable dual-phase heterogeneous structures using variable temperature rolling and annealing

A novel variable temperature rolling (VTR) and annealing process was conducted on a metastable austenitic stainless steel. Strain softening occurred during tensile straining in both cold rolled cryogenic rolled-annealed steels, leading to low uniform elongations of only 2-3%. In contrast, thanks the dual-phase heterogeneous lamellar structure achieved via VTR process, ultra-high strength over 1 GPa obtained, strain hardening led remarkable increase elongation up 10%. The high ductility are attributed significant work-hardening derived from superior deformation-induced sustained transformation-induced plasticity effect.