CHEVRON CRACKING IN MEDIUM STRENGTH LOW ALLOY STEEL WELDS

With a series of wire and flux combinations the chevron cracking in multipass submerged are welds has been studied. The morphology of the cracks was observed by means of the optical microscope and scanning electron microscope. The test results show the cracking being oriented at an angle approximately 45°to the plate surface in longitudinal sections. Chevron cracking is composed of small cracks created individually in the columnar boundaries and within the columnars of the welds. The fracture showed dimple or quasi-cleavage. Ion microprobe analysis verified that Mn, S, P and Ni have no direct relations to chevron cracking. There existed the segregation of Si along the chevron crack path. Weld metal of yield strength lower than 500N/mm² subjected to high plastic deformation consumption and residual stress may be liable to chevron. cracking.