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.