Dynamic and Static Recrystallization Behaviour of Coarse-grained Austenite in a Nb-V-Ti Microalloyed Steel

The dynamic recrystallization (DRX) and static recrystallization (SRX) behaviour of coarse-grained austenite in a Nb-V-Ti microalloyed steel were studied by using a Gleeble thermomechanical simulator. Continuous and interrupted compression tests of coarse-grained austenite were performed in the temperature range of 1000–1150 °C at a strain rate of 0.1–5 s−1 . The peak and critical strains for the onset of DRX were identified with strain hardening rate analysis, and the ratio of critical strain to peak strain was found to be consistent with the one reported for finegrained austenite. An equation of the time for 50% softening was proposed by considering the activation energy of steel without microalloying elements and the solute drag effect of microalloying elements. Strain-induced precipitation may not take place at the deformation temperature above 1000 °C, which indicates that SRX of coarse-grained austenite is mainly retarded by coarse grain size and Nb in solution during rough rolling.