Constitutive modelling of ratcheting behaviour for nickel-based single crystal superalloy under thermomechanical fatigue loading considering microstructure evolution

Based on the metallographic observation, the microstructure evolution of nickel-based single crystal superalloy under thermomechanical fatigue (TMF) loading is investigated, and respective phenomenological models of damage and rafting are developed. Considering that the deformation behaviour of material is closely related to their microstructures, new variables involving rafting evolution are incorporated to modify the hardening rule in order to overcome the inaccurate prediction in stable stage of ratcheting behaviour. Furthermore, by combining the continuum damage mechanics, a modified crystal plasticity constitutive model is proposed, and the ratcheting behaviour during the whole TMF lifetime, as well as hysteresis loops, can be simulated accurately.