Experimental evidence for bainite formation below Ms in Fe–0.66C

The isothermal decomposition of austenite in the temperature range 220–300 °C in Fe–0.69Mn–0.66C has been studied using dilatometry and scanning electron microscopy (SEM). Analysis of the dilatometry curves shows that after athermal martensite formation is interrupted below Ms = 264 °C, the austenite continues to decompose isothermally at a certain rate, which is in agreement with the kinetics of bainite formation above Ms. This strongly indicates that isothermal bainite is formed below Ms, which is supported by SEM images showing a mixed martensite–bainite microstructure.