Constitutive equation and microstructure evolution during isothermal compression of an Fe–26.6Mn–9.8Al–1.0C lightweight steel

This study investigates the constitutive equation and microstructure evolution of an experimental Fe–26.6Mn–9.8Al–1.0C lightweight steel at deformation temperatures of 850–1050 °C and strain rates of 0.01–5 s −1 via thermal–mechanical simulation. The flow stress curves of the steel are modified by considering the effects of friction and temperature rise. A high-temperature constitutive equation of the lightweight alloy is expressed using Arrhenius-type equation involving the Zener–Hollomon parameter, the constitutive equation based on peak stress and strain compensation (material parameters vary with different strain) were constructed, respectively, which can better predict the flow stress changes of the experimental steel during hot compression, the average absolute relative error (AARE) and R were calculated to be 5.6% and 0.98. DRX kinetic model of the experimental steel was also established, and the results show that the high temperatures and low strain rates are conducive to DRX. DRX is sensitive to thermal deformation temperatures and strain rates, but the sensitivity to temperatures is higher than that to strain rates. Deformation twin and dislocation slipping are the main deformation mechanisms in the experimental steel at the low deformation temperature of 850 °C. At the higher temperature of 1050 °C, the deformation mechanisms are dislocation slipping and deformation banding.