Effect of Reversible Cyclic Plastic Deformation and Thermal Treatment on the Microstructure and Mechanical Properties of SS304L Steel

In the present study, the effect of heat treatment and reversible cyclic plastic deformation (RCPD) on microstructure and mechanical properties of stainless steel 304L (SS304L) has been examined. The RCPD demonstrated a significant reduction in the grain size as well as formation of deformation-induced twins, without any observable phase transformation in the SS304L specimens. An isothermal annealing of as-received specimens at 950 °C (1223 K) for varying annealing durations exhibited the formation of recrystallized equiaxed austenitic microstructure. It was also observed that the grain size and the twin width increased simultaneously with annealing time, wherein the grain size increased linearly, whereas the increment in the twin width was parabolic in nature. The density of deformation twins decreased with increasing annealing time, which was attributed to the variation in the stacking fault energy (SFE) with temperature and duration of annealing treatment. The average hardness values decreased with increasing annealing time, and this trend was correlated with the increasing grain sizes and, simultaneously, decreasing amount of twin density.