Activation Energy and Zener-Hollomon Mapping of Hot-Deformed API X80 Steel Using Modified Hyperbolic Sine Constitutive Models
نویسندگان
1 Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran
2 Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3 Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran
doi
10.22099/ijmf.2025.53717.1336چکیده
This study investigates the hot deformation behavior of API X80 pipeline steel using modified hyperbolic sine-based constitutive models. Uniaxial compression tests were conducted at temperatures of 950 to 1100 °C and strain rates of 0.001 to 1 s⁻¹. Five constitutive approaches were evaluated: linear-linear Shi (LLS), linear-polynomial Shi (LPS), polynomial-polynomial Shi (PPS), and polynomial-polynomial Yang (PPY). Results indicate that activation energy (Q) varies significantly with deformation conditions. While the constant Q (CAE) model provides reasonable predictive accuracy and remains useful for simplified analysis, the PPY model demonstrates superior performance by capturing complex dependencies between stress, temperature, and strain rate. Zener-Hollomon (Z) maps and Q contours further illustrate the impact of model selection on process prediction. These findings establish a reliable computational framework for accurately modeling and optimizing hot deformation in high-strength steels.
