Effect of reverse austenitic transformation on mechanical property and associated texture evolution in AISI 316 austenitic stainless steel processed by low temperature rolling and annealing

Abstract

The tensile behaviour of austenitic stainless steel after cryorolling and subsequent annealing has been reported. The defect structures generated during cryorolling, lead to the formation of alpha' and epsilon-martensite. Subsequent annealing leads to the formation of refined austenitic grains surrounded by martensitic islands. These martensitic islands consist of alpha' phase only. The dislocation-martensite interaction leads to discontinuous yielding for high Ultimate Tensile Strength (UTS)/Yield Strength (YS) ratio. In case of annealing at 923 K (650 degrees C) for 10 min after 30% cryorolling leads to nearly 30% untransformed martensite whereas only 7% martensite remains after annealing for 1 h. The effect of remnant martensite on tensile behaviour leading to yield plateau has been discussed in this work. It can be noticed that sample with 20% cryo rolling and annealed at 650 degrees C for 1 h shows higher YS (721 MPa) with YS/UTS ratio of 0.79 and similar to 18% uniform elongation. Sample with 30% cryo rolling and annealed at 650 degrees C for 1 h shows YS of 305 MPa with YS/UTS ratio of 0.27 and uniform elongation of similar to 24%. Therefore, 20% cryo rolled and annealed at 650 degrees C for 1 h has the best combination of mechanical properties.