Hot Deformation Behavior and Processing Maps of a Medium Manganese TRIP Steel

The hot deformation behavior of a medium-Mn steel was studied in terms of hot compression flow curves in the temperature range of 850-1050 °C and strain rates of 0.05-10 s^-1. The thermo-mechanical analysis was carried out and suggested that the microstructure during deformation was completely austenite which had high tendency for dynamic recrystallization (DRX). The flow behavior was characterized by significant flow softening at deformation temperatures of 950-1050 °C and lower strain rates of 0.05-5 s^-1, which was attributed to heating during deformation, DRX and flow instability. A step-by-step calculating procedure for constitutive equations is proposed. The verification of the modified equations indicated that the developed constitutive models could accurately describe the flow softening behavior of studied steel. Additionally, according to the processing maps and microstructure analysis, it suggested that hot working of medium-Mn steel should be carried out at 1050 °C, and the strain rate of 0.05-10 s^-1 resulted in significantly recrystallized microstructures in the in steel. The flow localization is mainly flow instability mechanism for experimental steel.