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 similar to 2.0 mu m can be obtained using the experimental conditions described in the study, which is similar to 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.