Modeling the creep deformation and damage evolution of superalloy GH4169: Application of a novel damage constitutive model based on continuum damage mechanics

Abstract

In order to accurately predict creep deformation and damage evolution of nickel-based superalloy GH4169, a novel damage constitutive model, which can be called TTC CDM-based model, was proposed based on TTC relations and continuum damage mechanics (CDM). The stress and temperature dependence of constants were all determined in the novel model, which overcame the weakness of the traditional CDM-based model and made the model have the satisfactory abilities of interpolation and extrapolation. Microstructural study has revealed that the creep fracture mode gradually converts from intergranular brittle fracture to transgranular ductile fracture as the stress decreases. And the critical conditions were identified. It was determined that the novel model accurately predicted the minimum creep rate, rupture time, creep deformation and damage evolution process of GH4169. Furthermore, the nonlinear creep damage accumulation effect was also revealed by the novel model, i.e. the total creep life of GH4169 will be reduced if high stress or high temperature condition was applied first, which was consistent with previous experimental results of variable creep load.