Maintaining microstructure ultra-refinement in the austenitic stainless steel by inducing χ phase precipitating through severe cold rolling and annealing

Abstract

Abstract In the present study, an austenitic stainless steel (2Cr17Ni13Mo5) was processed by severe cold rolling (SCR) and subsequent annealing. The grain size was severely refined to ∼100 nm after SCR. The yield strength (YS) and ultimate tensile strength (UTS) increased to 1510.5 MPa and 1660.4 MPa, respectively. Nevertheless, the ductility decreased significantly. Full recrystallization was completed after annealing at 800 °C for 1h. However, the ultrafine-grained structure was maintained with the grain size of 780 nm, which is mainly attributed to the pinning effect of χ phase precipitated at the grain boundary during annealing. Good comprehensive mechanical properties with high strength (YS = 977.6 MPa, UTS = 1197.7 MPa) and good ductility (elongation = 17%) were obtained. The high strength is mainly attributed to the ultrafine-grained structure maintaining, while the annihilation of dislocation contributes to the ductility improvement.