The significance of microstructural evolution on governing impact toughness of Fe-0.2C-6Mn-3Al medium-Mn TRIP steel studied by a novel heat treatment

We address here the continuing challenge and scientific gap in obtaining high impact toughness in medium-Mn steels. While addressing the challenge, the objective of the study described here is to obtain a fundamental understanding via critical experimental analysis of the reasons underlying high impact toughness that was successfully obtained in Fe-0.2C-6Mn-3Al medium-Mn TRIP steel. Electron microscopy and X-ray diffraction studies clearly underscored the absence of the TRIP effect in Fe-0.2C-6Mn-3Al medium manganese steel during impact and the volume fraction of austenite played a determining role in governing impact toughness. The highest impact toughness of 213.6 J.cm(-2) was obtained when the steel was subjected to an intercritical hardening temperature of 700 degrees C and low tempering temperature of 200 degrees C. The presence of martensite in the microstructure reduced the impact toughness on quenching from 750 - 850 degrees C.