Study on dynamic recrystallization of ultra-high strength 22MnB5 steel during hot rolling

Abstract

The effect of deformation temperature and strain rate on the recrystallization behavior of ultra-high strength hot formed 22MnB5 steel was systematically studied by isothermal compression experiments, and the microstructure was characterized and analyzed. The results show that the peak stress and peak strain of 22MnB5 steel decrease with increasing deformation temperature and increase with increasing strain rate. The dynamic recrystallization of 22MnB5 steel is more sensitive to temperature and less affected by strain rate. The recrystallization behavior is significant during isothermal deformation above 1323 K. Based on the hyperbolic sinusoidal constitutive equation, the accurate prediction model of dynamic recrystallization grain size and a dynamic recrystallization critical strain model for 22MnB5 steel were established. The relationship between recrystallization austenite grain size and deformation temperature and deformation amount was obtained as follows: d=4.1×10³[ε·exp(350.38/RT)]. The critical strains of complete recrystallization and complete non-crystallization at each deformation temperatures were determined by the critical strain model, which can provide a basis for the optimization design of rolling process parameters.