Hot deformation behaviors of low-alloyed ultrahigh strength steel 30CrMnSiNi2A: Microstructure evolution and constitutive modeling. (March 2021) - Wang, Kang
Highlights: The hot deformation behavior and microstructure evolution of ultrahigh strength steel 30CrMnSiNi2A are investigated. The dynamic recrystallization behaviors are mainly dominated by the discontinuous dynamic recrystallization mechanism. The continuous dynamic recrystallization behavior caused by the rotation of subgrains takes place at high strain rate. An Arrhenius type model and a physically-based model are proposed for the hot deformation behavior of 30CrMnSiNi2A steel. Abstract: In this work, isothermal compression tests over wide ranges of deformation parameters (deformation temperatures and strain rates) are carried out for investigating the hot deformation behaviors of low-alloyed ultrahigh strength steel 30CrMnSiNi2A. For clarifying the effects of deformation parameters on microstructural evolution and dynamic recrystallization (DRX) nucleation mechanisms, the optical microscope (OM) and transmission electron microscope (TEM) are employed. It is found that DRX easily take place and the initial microstructures are greatly refined under low deformation temperatures (920 and 970 ° C ) or high strain rates (1 and 10 s -1 ). The DRX behaviors are nearly completed with the strain rate decreasing or deformation temperature increasing, and the DRXed grain growth takes place. Under high strain rates, the uncompleted DRX aggravates the inhomogeneous grain distribution, thus the average grain size initially decreases and then increases with the strain rate decreasing. It is also found that discontinuous DRX behavior characterized by grain boundary migration takes place under various deformation parameters. Besides, the dislocation cells and subgrains are detected under the strain rate of 10 s -1, which means continuous DRX mainly takes place under high strain rate. According to the experimental data, an Arrhenius type model and a physically-based model are constructed, respectively. The good agreements between the reproduced and measured stresses indicate that both models enjoy the excellent capability in reproducing the hot deformation behaviors of 30CrMnSiNi2A steel.