Dynamic recrystallization behavior of M50 steel during hot compression: Constitutive modeling, hot processing map, and CA model
Lingtong Zhang, Wang Li, Min Li, Cai Qi, Xuanrui Zhang, Qichun Sun, Yanlin Wang, Zidong Wang
Abstract
M50 steel, known for its excellent high-temperature mechanical properties, is widely used in critical components such as high-speed bearings. However, during hot working, it tends to exhibit coarse microstructures and uneven performance, compromising service reliability. To address this, hot compression experiments were systematically conducted to investigate its deformation behavior and optimize the hot working process. True stress-strain curves were obtained under deformation temperatures ranging from 890 °C to 1130 °C and strain rates of 0.05–10 s −1 . The activation energy for hot deformation was calculated to be 363,504 J/mol, and a constitutive model with high prediction accuracy was established, showing a correlation coefficient of 99.3 % with experimental results. A hot processing map was developed by combining power dissipation efficiency and flow instability criteria, identifying a stable DRX region at high temperatures and low strain rates. Taking grain refinement and stability into account, the hot working window was narrowed to 1030–1130 °C and 0.05–0.50 s −1 , yielding an average grain size of ∼2.54 μm. The results also indicated that increasing temperature or strain rate promotes DRX; under constant temperature, grain size decreases with increasing strain rate, while under constant strain rate, it increases with temperature. Excessively high strain rates may lead to stress concentration, abnormal grain growth, and reduced processing stability. Furthermore, a CA model based on the constitutive equation was developed to predict microstructural evolution. The simulation results agreed well with experimental data, confirming the model's accuracy and effectiveness in simulating the DRX behavior of M50 steel.