Thermo-mechanics Driven Dynamic Recrystallization Behavior and Mechanism in High Strength Martensitic Stainless Steel

The hot deformation behavior and dynamic recrystallization mechanism of a new High Strength Martensitic Stainless Steel (HSMSS) for aero bearing were systematically studied by the single-pass isothermal compression tests via theoretical calculations and multi-scale experimental characterizations. The true stress-strain curves and flow behaviors under different deformation temperatures of 900 °C to 1150 °C and strain rates of 0.01 to 10 s −1 were analyzed, and the critical deformation conditions for the occurrence of dynamic recrystallization were determined based on the Zener-Holloman model. Furthermore, it is found that the increasing deformation temperature and decreasing strain rate promote dynamic recrystallization. The correlation between the microscopic mechanism of dynamic recrystallization and deformation parameters is clarified. It is found that the high strain rate activates the post-dynamic recrystallization and improves the dynamic recrystallization fraction. And the relationship between strain-induced precipitations and deformation conditions is explored. Finally, based on the dynamic material model and Prasad instability criterion, the hot processing map is established, and the optimized processing parameters are determined. It indicates that softening mechanism modifies with the distinct power dissipation efficiency. The critical power dissipation efficiency in HSMSS is presented for the first time, and the high-resolution observation shows that the lower critical power dissipation efficiency is caused by the lower stacking fault energy. This study highlights a theoretical basis for the hot-working process and dynamic recrystallization mechanism in HSMSS.