Reversible Characteristics and Cycling Effects of the ε ↔ γ Martensitic Transformations in Fe-Mn-Cr Twip/Trip Steels

The variation of thermal characteristics of the ε ↔ γ transformation during thermal cycling and the effect of Cr content was studied in two Fe-Mn-Cr steels through cyclic DSC examinations. It was found that the martensite start temperature decreased and the austenite start temperature increased in the first cycles, then both stabilized after several cycles. The latent heat of the transformations increased first and then also stabilized. The Cr content pushed the ε ↔ γ transformations to lower temperatures, decreased the thermal hysteresis and the latent heat. It is experimentally shown that 6.53 m/m% Cr content increases the stacking fault energy in this alloy.