Correlation between grain size and flow stress during steady-state dynamic recrystallization

The mechanical behaviour and microstructure evolution during hot deformation remain a fundamental industrial topic for metallic materials. In the present paper, the correlation between grain size and flow stress during steady-state dynamic recrystallization (DRX) has been investigated from an internal-variable perspective. From the competition between work-hardening and recrystallization softening, a dynamic model of DRX evolution has been generalized by proposing an identification criterion on DRX continuity or periodicity. The dependence of grain size on deformation parameters under the DRX steady state has been obtained from the dynamic balance. An Arrhenius constitutive model for the DRX steady state has also been constructed from the Estrin-Mecking formula, and the stress exponent has been fixed as a constant equal to 6. The correlation between grain size and flow stress has been validated as an inverse proportion with the relevant exponent n=1/2. In addition, the influence of deformation parameters on flow curve shapes and grain coarsening/refinement has been characterized correspondingly.