Critical Condition of Dynamic Recrystallization in 35CrMo Steel

The compression deformation behaviors of 35CrMo steel at different conditions was studied by using Gleeble-3810 thermo-simulation machine under large strain. The results indicate that the flow stress curves of 35CrMo steel is affected by strain rate and deformation temperature, showing the characteristics of dynamic recovery (DRV) and dynamic recrystallization (DRX), which is the main softening mechanism of 35CrMo steel. The activation energy (Q) and Zener-Hollomon parameter (Z parameter) expression for thermal deformation of this steel was calculated by linear regression. The inflection point on the curve of strain hardening rate and flow stress (theta-sigma curve) corresponds to the beginning of DRX, and the critical strain of DRX increases with the decrease of deformation temperature and the increase of strain rate. Based on the inflection point criterion, the constitutive equation of the critical strain of DRX of 35CrMo steel was established: epsilon(c) = 0.000232Z(0.1673), which reflects the variation of the critical strain of DRX with the Z parameter. In addition, through metallographic observation, the rationality of the inflection point criterion in determining the critical strain of DRX of 35CrMo steel was verified, and the DRX state diagram was established.