Analysis of Interface Fracture on Piping Welded Joint with Continuous Material Properties

Based on a numerical simulated approach of the continuous change of material mechanical property, a pressure piping welded joint with semi-elliptical surface crack is studied, the effect of the welded mechanical heterogeneity on the stress-strain fields and J-integral along the interface crack fronts at different locations are simulated. The results of this investigation show that the maximal stress, strain and J-integral are located at the crack front center point, the minimal stress and strain are located at the piping inner surface. Crack lies in the weld metal is more susceptible to propagate, and the propagating tending direction of the crack near the line dividing the weld metal and heat affect zone is the weld metal.