Influence of Deformation-Induced Martensite on Non-masing Behavior of 304L Stainless Steel

This study focuses on understanding the influence of deformation-induced martensite (DIM) on cyclic plastic deformation and non-Masing behavior of 304L stainless steel (SS). Low cycle fatigue (LCF) tests and corresponding microstructural investigations were done at +/- 0.25, +/- 0.6, and +/- 1.0% strain amplitudes at a total strain rate of 1 x 10(-3)/s. Further, numerical simulations were carried out for different martensite fractions formed during LCF loading. Depending on martensite fraction and applied strain amplitude, the development of stress/strain fields around the martensite due to deformation incompatibility between the austenite and martensite leads to the formation of deformation band-like plastic zones in austenite. The strain localization and microstructural heterogeneities increased with increased martensite fraction, leading to a change in the shape of the hysteresis loop and, subsequently, the Masing/non-Masing behavior. The fatigue life of 304L SS decreased with an increase in strain amplitude vis-a-vis increased martensite fraction. The research aims to enhance the understanding of the influence of DIM on cyclic stress-strain response, fatigue life, and the non-Masing behavior of 304L SS under LCF loading.