Modeling the hot flow behavior of a Fe-22Mn-0.41C-1.6Al-1.4Si TWIP steel microalloyed with Ti, V and Nb

The present research work analyses the influence of Ti, V and Nb microalloying elements on the hot flow behavior of a high-Mn Twinning Induced Plasticity (TWIP) steel. For this purpose, flow curves were obtained by uniaxial hot compression tests performed at four strain rates (10−1, 10−2, 10−3 and 10−4 s−1) and three temperatures (900, 1000 and 1100 °C). The models of Estrin, Mecking and Bergstrom; Avrami and Tegart, and Sellars were applied to determine the hot working constants used to derive the constitutive equations describing the flow curves. The analysis of modeling parameters of the hot flow curves shows that Ti, V and Nb additions to TWIP steel generated slight increase in the peak stress (σp), retardation of the dynamic recrystallization (DRX) onset, particularly at low temperature, and decrease in the activation energy required to recrystallization (Qt). Likewise, the softening effect promoted by DRV and DRX was more evident at high temperatures and low strain rates. On the other hand, the resulting deformed microstructures, analyzed by the SEM-EBSD technique, showed that the most important refining effect on recrystallized austenitic grain was in the presence of V and Ti. The good agreement between the experimental and predicted hot flow curves demonstrated that the developed constitutive equations predict with reasonable accuracy the hot flow behavior of the studied TWIP steels.