Hot Deformation Behavior of the 25CrMo4 Steel Using a Modified Arrhenius Model

• Published in: Materials Vol. 15; no. 8; p. 2820
• Main Authors: Xu, Hongtu, Tian, Tiantai, Zhang, Jiahao, Niu, Liqun, Zhu, Hongbin, Wang, Xingtao, Zhang, Qi
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 12.04.2022; MDPI
• Subjects: 25CrMo4 steel; Accuracy; Chromium molybdenum steels; constitutive model; Constitutive models; Correlation coefficients; Coupling; Deformation; Dislocation density; Dynamic recrystallization; Electron backscatter diffraction; Grain boundaries; High speed rail; hot deformation; Mathematical models; Mechanical properties; Microstructure; microstructure evolution; Neural networks; Strain analysis; Strain rate; Stress-strain curves; Temperature; Temperature effects; Thermal simulation; Thermal simulators; Titanium alloys; True stress; 25CrMo4 steel; microstructure evolution; constitutive model; hot deformation
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15082820

25CrMo4 steel is widely used in the manufacturing of high-speed train axles due to its excellent mechanical properties. The purpose of this study is to develop an accurate modified constitutive model to describe the hot deformation behavior of the steel. Isothermal compression experiments were performed at different strain rates (0.01, 0.1, 0.5, and 1 s ) and different temperatures (950, 1000, 1050, and 1100 °C) using a Gleeble-3800 thermal simulator. The microstructure after hot deformation was observed by the electron backscatter diffraction (EBSD), and the effects of temperature and strain rate were analyzed. The results showed that the coupling effect of temperature and strain rate on the dislocation density led to the change in the shape of the true stress-strain curve and that dynamic recovery (DRV) and dynamic recrystallization (DRX) caused the macroscopic softening phenomenon, with DRX being the main mechanism. Based on the true stress-strain curves, the strain-compensated Arrhenius constitutive model was calibrated. To improve prediction ability, a modified Arrhenius constitutive model was proposed, in which the temperature and strain rate coupling correction functions were incorporated. The original, modified Arrhenius models were evaluated according to the absolute relative error (ARE), the average absolute relative error (AARE), and the correlation coefficient (R ). Compared with the original model, the modified Arrhenius model has a higher prediction accuracy, with the ARE value mostly below 4%, the AARE value of 1.91%, and the R value of 0.9958.