Study on the Critical Condition and Deformation Mechanism of Dynamic Recrystallization of Novel Lightweight Steel Based on the Work Hardening Rate

In this work, the stress-strain curves of the experimental steel were obtained after isothermal compression deformation within the temperature 850—1 050 °C of and the strain rate of 0.01—5 s-1 on Gleeble3500 thermal-mechanical simulator. The work hardening rate-strain curves, dynamic recrystallization critical stress and critical strain of the experimental steel were further obtained by data processing. The microstructures evolution and deformation mechanism of the experimental steel were analyzed by OM, TEM and EBSD. The results show that for the experimental steel, there is an obvious ‘secondary increase’ phenomenon of the flow stress, for the the dominant position is occupied again by work hardening as the strain increases at relatively low temperature and low strain rate. The peak stress, critical stress, peak strain and critical strain of the experimental steel show an increasing trend, as the deformation temperature decreases and the strain rate increases, and simultaneously, a new relationship model between them is obtained. The recrystallization grain size of the experimental steel increases with the increase of temperature and the decrease of strain rate, and the stacking fault energy (SFE) ranges from 181.1 mJ/m2 to 237.4 mJ/m2, which exhibits increasing trend with the increase of temperature under the deformation condition. It can be concluded that stacking fault energy is not the only factor affecting the deformation mechanism of the experimental steel because of the presence of the twins after hot deformation of the experimental steel. Dislocation slipping is the main deformation mechanism of the experimental steel. © 2022 Cailiao Daobaoshe/ Materials Review. All rights reserved.