Simulation of Cyclic Deformation Behavior of Ferritic P92 Steel Based on Unified Viscoplastic Model

摘要

Creep-fatigue interaction (CFI) behavior of P92 steel was investigated at high temperature of 600 °C by employing different hold time in tensile and compressive hold directions. Axial strain controlled CFI tests were then conducted in trapezoid waveform. Tension and compression hold up to 60 min and 10 min were conducted respectively to clarify the influence of hold time and hold direction. Results show that existing of tensile hold time increases the cyclic softening while compressive hold has reversed effect. In addition, it has been achieved that softening ratio of P92 steel is more sensitive to tensile hold than compressive hold. Moreover, a unified viscoplastic model with a modified isotropic variable is proposed to simulate the material's cyclic deformation behavior at low cycle fatigue (LCF) and CFI loadings. The hysteresis loops, peak stress evolution and stress relaxation behavior during hold time are all simulated. Comparison of the simulated and experimental results shows that the proposed model is reasonable to simulate the cyclic behavior of P92 steel.