Effect of cryorolling on the microstructure and tensile properties of bulk nano-austenitic stainless steel

We report the synthesis of nanostructured austenitic AISI 304L stainless steel (SS) through cryorolling (CR) and reversion annealing in the temperature range of 700-800 °C. Severe CR at sub-zero temperature promotes twinning in γ-austenite, which transform into α׳-martensite with lath thickness of 50-100 nm. Whereas, 50-300 nm size γ-grains recrystallize in nano-twinned α׳ through reversion annealing as confirmed by transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD) imaging. The evolution of highly processable bulk nano-austenitic SS with bimodal grain size distribution on achieving high strength (~1295 MPa), large tensile ductility (~0.47), and true necking strain of 0.59, have been discussed.