Modeling of the Dynamic Recrystallization of Ti Microalloyed High‐Strength Steel

Abstract

The dynamic recrystallization (DRX) and austenite microstructure evolution of Ti microalloyed high‐strength steel are investigated and modeled by thermal simulation experiments. The corresponding mathematical models are established based on DRX‐type flow stress curves and the austenite microstructure. A highly accurate austenite grain growth model under different heating conditions is established, which can predict the initial austenite grain sizes before deformation. Considering the effect of initial austenite grain sizes and deformation conditions, the key parameters (peak stress, steady stress, peak strain, and constants C and C1) of the DRX‐type flow stress model are determined, and the predicted DRX‐type flow stresses are in good agreement with the experimental values. The relationships between critical strain and peak strain(εc = 0.77εp), critical stress, and peak stress(σc = 0.82σp) are determined for experimental steel. The relationships between the initial austenite grain size and the key parameters (k, M, a, h) in the DRX kinetic model and the DRX grain size model are determined. The calculated and experimental DRX volume fractions and grain sizes are in good agreement. The results show that these mathematical models can accurately describe the DRX behavior of experimental steel.