Constitutive Model and Hot Processing Maps of Fe-10Mn-2Al-0.1C Medium Mn Steel

Hot compression tests at deformation temperatures of 900-1 100 ℃ and strain rates of 0.01-10 s^-1 were conducted on Fe-10Mn-2Al-0.1C (mass fraction/%) medium Mn steel by using a Gleeble-1500 thermo-mechanical simulator. The Zener-Hollomon constitutive model of the test steel was established by a strain compensation method with the test data, and verified by the tests. The hot processing maps of the test steel at true strains of 0.2, 0.4, 0.6, 0.8 were established on the basis of the dynamic material model (DMM). The results show that the correlation coefficient between the flow stresses predicted by the established constitutive model and the measured stresses was 0.987, indicating that the model can be used to describe the thermal deformation behavior of the test steel. According to the calculation by the constitutive model, when the true strain increased from 0.1 to 0.8, the hot deformation activation energy of the test steel was reduced from 476 kJ·mol^-1 to 342 kJ·mol^-1. According to the hot processing maps, the optimal hot working conditions of the test steel were determined as deformation temperatures of 900-940 ℃ and strain rates of 0.01-0.03 s^-1, and deformation temperatures of 1 070-1 100 ℃ and strain rates of 0.1-0.56 s^-1; the power dissipation efficiency under these conditions was 32%-38%.