Finite element analysis on grain boundary diffusion controlled cavity growth during high temperature fatigue

Abstract

Finite element analysis on the growth of grain boundary cavity during high temperature low cycle fatigue is carried out. A finite element code is developed to solve this special initial-boundary value diffusion problem. The growth rates of the cavity by vacancy diffusion under the conditions of various strain rates are calculated. The size of the cavity nucleus calculated by thermodynamics is taken as the initial cavity size. The analysis results show that a cavity can be grown by the diffusion of grain boundary vacancies when the strain rate is below a critical value. However, it can be seen from the analysis that the growth rate is very low. The results coincide with the fact that the main cause of intergranular fracture under the condition of low cycle fatigue is the high nucleation rate of cavities.