Plastic r) factor considering strength mismatch and crack location in narrow gap weldments

摘要

The fracture toughness for LBB analysis of piping is generally determined in terms of thej-integral according to ASTM El 820. The J-integral consists in the elastic componentJet and the plastic part J_(pl). Experimental evaluation of J_(pl) requires the plastic η factor. The J-integral evaluation by ASTM method was developed, however, essentially for homogeneous material. The fracture toughness of a strength mismatch weld evaluated as per ASTM method can, thus, differ from its actual value. In this study, the plastic η factors of similar as well as dissimilar metal narrow gap weld are suggested considering the influence of weld strength mismatch, weld width, and crack location. The proposed plastic η factors are compared with detailed finite element results. Few fracture tests were performed to quantify the influence of weld strength mismatch on fracture toughness of low alloy steels using C(T) specimens.