Simultaneous Occurrence of Twinning and Phase Transformation During Yield Point Elongation in Medium Manganese Steels

In this work, we report nearly 8 pct yield point elongation during deformation of medium Mn steel (Fe–5Mn–0.2C–0.8Si–0.34Al). Detailed investigation of the deformation mechanisms shows that in addition to slip in ferrite and austenite, phase transformation and twinning (TRIP and TWIP) occur simultaneously in the austenite phase. This is attributed to differences in Mn concentration in austenite grains which changes the stacking fault energy; thereby altering the dominant deformation mechanism from phase transformation to twinning.