Crack tip fields effects on crack propagation through the heat affected zone in an overmatched welded joint

Abstract

The mismatching constraint effect on crack propagation through the heat‐affected zone (HAZ) in a welded joint is presented in this paper. It is shown that due to this effect, the fracture behavior of an overmatched welded joint depends on the mechanical properties and the size of the region of the crack tip location, as well as on the properties and the size of surrounding regions. The finite element analysis of high‐strength low‐alloyed (HSLA) steel welded joints with crack tips in the heat‐affected zone is performed based on previous experimental work. Two locations of the crack tip are analyzed: fine‐grained HAZ (FGHAZ) and coarse‐grained HAZ (CGHAZ). In both cases, after the initial propagation of the crack in FGHAZ or CGHAZ, its propagation is directed toward more ductile base metal, thus increasing the fracture resistance of a welded joint. Some new observations about the reasons for such behavior due to crack tip strain fields are presented as well.