Exceptionally high strength and good ductility in an ultrafine-grained 316L steel processed by severe plastic deformation and subsequent annealing

摘要

An investigation was conducted to evaluate the effect of annealing at different temperatures on the tensile properties of ultrafine-grained 316L stainless steel processed by high-pressure torsion (HPT). A “moderate-temperature” annealing at 740 K resulted in reduced strength and elongation due to the annihilation of mobile dislocations. A “high-temperature” annealing at 1000 K yielded a remarkably good combination of yield strength (~1330 MPa) and elongation to failure (~43%) which can be attributed to the almost full reversion of α’-martensite formed during HPT into γ-austenite while the grain size remained very fine with avalue of about 200 nm.