Hot deformation behaviour and processing map of a typical Fe-Mn-Si-Cr steel for automotive body structures

ABSTRACTThe hot deformation behaviour and processing maps of a typical Fe-Mn-Si-Cr steel for automotive body structures were investigated on a Gleeble3500 simulation tester by isothermal compression test in the temperature ranging of 950°C to 1150°C and a strain rate of 0.05–10 s−1. The results show that dynamic recrystallisation softening mechanism is more evident at low strain rate, while dynamic recovery is more evident at high strain rate. The instability parameter ξ(e˙) values are negative and considered as unsafe deformation zones at low deformation temperature and high strain rates. The processing maps exhibit two safe domains for hot working: (a) 0.05–1 s−1 and 1080–1150°C, the power dissipation values of η increase with the increase of strain rate. (b) 0.05–1 s−1 and 950–1020°C, while strain is lower than 0.1, the values of η decrease with the increase of strain rate.