Study on hot deformation behavior of carbon structural steel with flow stress

The hot deformation behaviors of carbon structural steel were investigated using isothermal compression tests performed on a Gleeble 3500 thermal-mechanical simulator at temperatures of 950–1050 °C, and strain rates of 0.01–0.5 s−1. Austenite grain growth behavior under different heating conditions was also studied. The relationships among average grain size, soaking temperature, and time were determined. The flow stress under dynamic recrystallization (DRX) conditions was analyzed, and the critical strain, as a function of the deformation parameters, was measured. The dependence of peak strain on strain rate and temperature obeys a hyperbolic sine equation with a Zener–Hollomon parameter. Using regression analysis, the DRX activation energy was determined and the DRX grain size model of the steel was constructed. Meanwhile, an approximate model based on the flow curves was investigated to determine the recrystallized fraction under different conditions, after which the DRX kinetics model was established. The model predictions show good agreement with the experimental results.