Effect of welded mechanical heterogeneity on local stress and strain ahead of stationary and growing crack tips

The crack tip stress and strain condition is one of main factors affecting environmentally assisted cracking (EAC) behaviors in light water reactor (LWR). The mechanical and material properties of the base metal, weld metal and heat-affected zone (HAZ) in welded joints are heterogeneous because of the inherent characteristics of welded joint. Since the welded joint is more susceptible to EAC, to understand the effect of the strength mismatch in the welded joint on EAC growth rate, the stress and strain state in both stationary and growing crack tips of the welded joint specimen are investigated by the elastic-plastic finite element method (EPFEM) in this paper. The results indicate that the strength mismatch and sampling position in the welded joint would observably affect the stress and strain ahead of the stationary and growing crack tip, and accordingly affect the EAC growth rate