Dynamic and post-dynamic recrystallization in a Mo-Ti steel

Simulations of hot strip mill and other tandem schedules have shown that dynamic recrystallization can take place if static recrystallization is sufficiently retarded to permit the required amount of strain accumulation. This condition is satisfied when the rate of static recrystallization is reduced by solute drag and the interpass times are short. Once dynamic recrystallization is initiated, the microstructure during the interpass time will be subject to post-dynamic recrystallization. Although the characteristics of dynamic recrystallization are well documented, very few data are available on the kinetics of the post-dynamic process, which includes both metadynamic and conventional static recrystallization. Continuous and interrupted tests were applied to a Mo-Ti microalloyed steel in torsion. Initial experiments involved straining to the steady state, in order to determine the peak stress and strain for dynamic recrystallization under various deformation conditions. Then, interrupted tests were performed at the peak and after the peak, which established the effect of strain rate, temperature and strain on the softening kinetics. A description of the influence of these test variables on the time for 50% static softening is given, along with an interpretation of the mechanisms contributing to this effect.