Numerical Research of Ductile Crack Growth Behavior for Dissimilar Metal Welded Joint of Nuclear Pressure Vessel

Based on GTN damage model and finite element method（FEM）,numerical simulations are performed on the specimens of a nuclear power dissimilar metal welded joint（DMWJ）,and the crack growth paths and J-R resistance curves were obtained.Results show that the crack growth paths for the central cracks in the buttering and weld material are nearly the same as those of the homogenous material crack,while the growth paths for interface crack and near interface crack in the DMWJ deviate from their initial positions significantly.The initial interface crack and near interface crack tend to grow in the soft material with low yield stress,and is mainly caused by the strength mismatch of the different materials.The cracks with different initial location and depth have different strength mismatch and geometry constraint,and result in different J-R resistance curves.The growth paths and resistance curves of these cracks could not be predicted by macroscopic fracture mechanics;while the numerical simulation of finite element based on GTN damage model is expected to be used in structural integrity assessment for safe-end DMWJ and leak-before-break analysis.