Dependence between η -factor and crack location relative to a fusion boundary between hard and soft materials in a SE(B) specimen

The current solutions in ASTM E1820 and E1921 for the calculation of the J-integral are not necessary directly applicable for strength mismatched welds. The problem is connected to the η-factor relating the experimentally measured work to the J-integral. Previous, investigations on η-factors for welds have focused mainly on cracks at the center of the weld. However, characterisation of the η-factor at other locations is also important since the crack can form anywhere in the weld. In this study, the η-factors for SE(B) specimens were investigated, with focus on the effect of the crack location relative to the fusion boundary between a hard base metal and a soft weld metal of a dissimilar metal weld. The results show a dependence between the η^CMOD-factor, the distance of the crack to the fusion boundary, the size of the remaining ligament, and the size of the plastic deformation zone. This dependence cannot be generalised based on this study alone, but the results give insight for developing an analytical η^CMOD-equation for strength mismatched specimens.