Dynamic Recrystallization Behavior of Low-Carbon Steel during the Flexible Rolling Process: Modeling and Characterization

Dynamic recrystallization (DRX) is the predominant softening mechanism under high-temperature large-plastic deformation and determines the microstructure evolution of steel. Herein, an equivalent substitution method is proposed to investigate the coupling effect of deformation conditions on microstructural evolution during the flexible rolling process. Low-carbon steel is compressed using a Gleeble 3800-GTC thermal–mechanical physical simulation system at temperatures ranging from 900 to 1100 °C and strain rates ranging from 0.01 to 10 s−1. The flow stress behaviors under different deformation conditions are discussed. Accordingly, the relationship between strain rate and temperature is established using the Zener–Hollomon equation. Further, a new DRX model is proposed by combining the theoretical implications of previous models. The effectiveness of the experimental model and predicted model is statistically evaluated to accurately determine the DRX volume fraction of the experimental steel. Based on the dynamic material model, a hot processing map of the experimental steel is also developed to evaluate the steel's hot workability. Finally, the microstructure of the experimental steel is analyzed under specific deformation parameters. The results demonstrate that DRX behavior decreases as the upper roller is raised and the lower roller is lowered during the flexible rolling process.