Deformation behavior of high yield strength - High ductility ultrafine-grained 316LN austenitic stainless steel

The concept of phase reversion annealing involving extensive cold deformation of metastable austenite to strain-induced martensite, followed by annealing at slightly elevated temperature, developed by Misra's group in recent years [2-5] was used to obtain ultrafine-grained structure in a 316LN austenitic stainless steel. The primary objective of this study is to elucidate the deformation mechanisms. The study suggested that an average austenite grain size in the ultrafine regime of ~2.0 μm can be obtained using the experimental conditions described in the study, which is ~6 times finer than the grain size of commercial 316LN steel. The grain refinement led to high yield strength in ultrafine-grained 316LN steel without any significant compromise in ductility. The high plasticity of ultrafine-grained 316LN steel is attributed to the presence of mechanical twins.