Cyclic Mechanical Behavior, Damage-Coupled Constitutive Model, and Remaining Life Prediction Model of QCr0.8 at High Temperature

The low cycle fatigue (LCF) behavior including the fatigue life, hysteresis loop, and damage process of QCr0.8 at 350°C and 500°C was studied. A viscoplastic damage-coupled unified creep-plasticity constitutive model was developed to simulate the cyclical mechanical behavior and damage of QCr0.8 with the same set of parameters at identical temperatures. Meanwhile, LCF damage measurement methods based on changes in elastic modulus and evolution of peak stress were compared. To assess the remaining life of QCr0.8 after a certain period of service, a remaining life prediction model based on the entropy increase theory within the unified thermodynamic framework was proposed. The results show that the prediction results are in good agreement with experimental data.