A novel damage constitutive model for creep deformation and damage evolution prediction

In order to accurately predict creep deformation and damage evolution of nickel-based superalloy GH4169, a novel damage constitutive model, that is, TTC CDM-based model, was proposed based on TTC relations and continuum damage mechanics (CDM). This model combined the best features of the TTC relations and CDM. The recently developed TTC relations were intrinsic relations between threshold stress, tensile properties, and creep behavior and exhibited better prediction ability than Wilshire equations. It was determined that the model accurately predicted the minimum creep rate, rupture time, creep deformation, and damage evolution process of GH4169. Microstructural study has revealed that the creep fracture mode gradually converts from intergranular brittle fracture to transgranular ductile fracture as the stress decreases. Furthermore, the nonlinear creep damage accumulation effect was also revealed by the novel model.