Extraordinary warm ductility of a Mn-rich high-strength steel achieved at temperature below 0.5 Tm

Abstract This work employed austenite reversion during deformation to achieve large ductility at a temperature below 0.5 Tm (melting temperature) in Mn-rich high strength steels. This goal was achieved in a Mn-rich steel without Al, in which a higher austenite reversion rate below 0.5 Tm was obtained. The tensile results evidenced that extraordinary ductility of over 90% at 550 °C, which is about 0.48 Tm of the steel. Thermodynamic calculation was applied to elucidate the effects of Al and strain energy. Moreover, electron backscatter diffraction was used to investigate microstructure evolution under various conditions. It was found that rate of austenite reversion is more critical than ferrite recrystallization in enhancing ductility during warm deformation.