Journal of Materials Research and Technology (May 2020)
Microstructure and hot deformation behavior of FeMnAlCMo steel
Abstract
The hot deformation behavior of the lightweight Fe-30Mn-10Al-1.1C-4Mo steel was experimentally investigated under compression, tension, and torsion with tension conditions and simulated by the finite element method. The as-cast microstructure of the Fe-30Mn-10Al-1.1C-4Mo steel consists of the bcc phase, fcc phase, and Mo-containing carbides. Annealing of the steel at 1100 °C for 5 h leads to the disappearance of the bcc-phase and a decrease in the carbides volume fraction from 5.6% to 1.3%. The stress–strain curves show that the dynamic recrystallization proceeds during hot compression at the temperature of 900–1100 °C and the strain rate of 0.1–10 s−1. The constitutive model of hot deformation shows that the effective activation energy is in the range of 380–405 kJ/mol, which is higher on approximately 100 kJ/mol in comparison with Mo-free FeMnAlC steels. The critical values of the Rice and Tracy fracture criteria are in the range of 0.84–1.55 depending on the tension conditions. The linear dependence of the fracture criteria on the logarithm of the Zener–Hollomon parameter was found. The hot deformation and fracture models were confirmed by finite element simulation of the torsion with tension tests at 1000 and 1100 °C. The average error of the determination of the rotation angle until the fracture is about 15%, which shows good promise of the constructed model for the development of the hot deformation industrial technologies for the Fe-30Mn-10Al-1.1C-4Mo steel using finite element simulation.
