A Khosravifard - Department of Materials Engineering, Shiraz Branch, Islamic Azad University, Shiraz 71955, Iran

In this study, dynamic mechanical properties of three high-manganese steels with TRIP/TWIP or fully TWIP characteristics are studied. High strain rate experiments in the range of true strain rates between ~500 and 1800 /s were conducted using a dynamic torsional testing setup. All the three steels show a positive strain rate sensitivity in the intermediate range of strain rates (up to 500 /s). But, they behave differently as the strain rate is further increased. The steel with the lowest carbon content shows a strain rate softening behavior, while the other two exhibit strain rate hardening. The adiabatic temperature rise of the material greatly influences its stacking fault energy during the high rate dynamic deformation. Thus, unlike the quasi-static experiments, the dominant deformation mechanism of the steel during a dynamic test changes as the deformation progresses. In this regard, the variations of the stacking fault energy during the deformation are calculated for the three steels.

High strain rate, TRIP/TWIP steel, stacking fault energy, adiabatic temperature rise