The modelling of dynamic recrystallization in the isothermal compression of 300M steel

The 300M steel was isothermally compressed on a Gleeble-3500 simulator at the deformation temperatures ranging from 1123 K to 1473 K, the strain rates ranging from 0.1 s−1 to 25.0 s−1 and the strains ranging from 0.36 to 1.2. The morphology of austenite grains in the isothermally compressed 300M steel was observed using an OLYMPUS PMG3 microscope. The experimental results of DRX behavior and microstructure observation showed that dynamic recrystallization occurred more easily at higher deformation temperature and lower strain rate. Based on the work hardening rate versus flow stress curves, the critical strain was identified to express the initiation of dynamic recrystallization. In order to determine the kinetics of dynamic recrystallization, the Avrami equation based on the flow stress–strain curves was established. The austenite grain size of complete dynamic recrystallization was a power law function of Zener–Hollomon parameter with an exponent of −0.22.