A damage-coupled unified constitutive modelling for predicting the deformation behaviour of 316L under isothermal fatigue and thermo-mechanical fatigue loading conditions

Isothermal fatigue (IF) and thermo-mechanical fatigue (TMF) tests are conducted on type 316L austenitic stainless steel within a temperature range of 475 °C–625 °C under symmetric strain-controlled condition. The results indicate that 316L exhibits significant cyclic hardening, strain range memory effect (SRME), temperature history effect (THE), and phase angle effect (PAE). An improved damage-coupled unified viscoplastic constitutive model (DCUVCM) is accordingly developed based on the framework of Chaboche model and a widely-utilized creep-fatigue interaction damage model. In which, cycle- and maximum inelastic strain amplitude-dependent scalar functions are coupled into nonlinear kinematic hardening rules (KHRs) and isotropic hardening rules (IHRs) to describe cyclic hardening and SRME. THE is explained by introducing temperature rate terms into both the KHR and IHR. Moreover, a novel phasing coefficient is incorporated into the damage variable to describe the PAE. Eventually, the excellent agreement between experimental and simulated results under both IF and TMF loadings demonstrates the robustness of the proposed DCUVCM in predicting the whole-life cyclic response and fatigue life of 316L.