Main mechanical factors affecting creep strain at crack tip of stress corrosion cracking in full life cycle

Abstract

Stress Corrosion Cracking (SCC) is a failure mechanism that is caused by environment, susceptible material and tensile strain at crack tip. The mechanical state at crack tip is one of the main factors affecting stress corrosion crack propagation rate in structural materials of nuclear power plants. To understand the effect of mechanical factor on creep strain on SCC crack growth rate in the light water reactor environments, the creep strain at crack tip in full life cycle is studied by elastic-plastic finite element method (EPFEM) in this paper. Study results indicate that it is suitable to use the creep strain in front of crack tip as a mechanical factor of SCC behaviors, and also show that wedging stress is the main mechanical factor affecting creep strain in micro crack stage, while external load are gradually becoming the main mechanical factor in long crack stage. Crack propagation rate is very slow in micro crack stage, and it will expand rapidly under the combined effect of residual stress and working load if there is an initial crack l.