Predicting Critical Conditions and Stress-Strain Curves for Dynamic Recrystallization in SPHC Steel

The hot compression tests on an SPHC steel were carried out in the temperature range of 900–1150°C and strain rate range of 0.1–10 s−1, in which the maximum true strain is 0. 8. The activation energy of test steel was calculated, to be 299.4 kJ/mol. The critical stresses and strains for initiation of dynamic recrystallization were determined based on changes of the work hardening rate (θ) as a function of the flow stress (σ) or strain (ɛ), respectively. The dependence of the peak strain (ɛp), the peak stress (σp), and the steady state stress (σs) were determined based on the Zener-Hollomen parameter. The mathematical models of the flow stress evolution were established in the hardening and dynamic recovery region and dynamic recrystallization region, respectively. The average error between experimental curves and predicted ones was around 3.26%.