Effects of thermal cycling on the kinetics of the γ → ε martensitic transformation in an Fe-17 Wt pet mn alloy

The thermal cycling of an Fe-17 wt pet Mn alloy between 303 and 573 K was performed to investigate the effects of thermal cycling on the kinetics of the γ → ε martensitic transformation in detail and to explain the previous, contrasting results of the change in the amount of ε martensite at room temperature with thermal cycling. It was observed that the shape of the γ → ε martensitic transformation curve (volume fraction vs temperature) changed gradually from a C to an S curve with an increasing number of thermal cycles. The amount of e martensite of an Fe-17 wt pet Mn alloy at room temperature increased with thermal cycling, in spite of the decrease in the martensitic start (Ms) temperature. This is due to the increase in transformation kinetics of e martensite at numerous nucleation sites introduced in the austenite during thermal cycling.