Study of microstructural evolution during metadynamic recrystallization in a low-alloy steel

Using Gleeble-1500 thermo-mechanical simulator, the microstructural evolutions during metadynamic recrystallization of 42CrMo steel were investigated by hot compressive deformation tests at forming temperatures of 850–1150 °C, strain rates of 0.01–1 s−1, and initial austenite grain sizes of 54–155 μm. The effects of forming temperature, strain rate and the initial austenitic grain size on the microstructural evolution during metadynamic recrystallization in hot deformed 42CrMo steel were discussed in detail. Based on the experimental results, the grain size model for metadynamic recrystallization was established. It is found that the effects of forming parameters (temperature and strain rate) on the microstructural evolution during metadynamic recrystallization are significant, while those of the initial austenitic grain size are obvious only when the initial austenitic grain size is less than 104 μm. A good agreement between the experimental and predicted grain sizes was obtained, which verified the developed grain size model.