Environment-sensitive fracture: material and welding considerations

Abstract

AbstractFusion welding is widely employed in the fabrication of metallic constructions, and this has a number of consequences concerning the possibility of environmentally assisted failure occurring in subsequent service. In the weld region the material microstructure and composition can vary greatly over a relatively small distance, especially as the welding consumables used seldom fully match the composition of the parent material. In addition, the joint surface will generally be irregular, with an associated stress-concentration effect and a propensity for ‘hideout’ of aggressive chemical species, while unless a post-weld heat treatment is applied the weld fabrication will contain residual welding stresses. Moreover, a fusion-welding operation can lead to the formation of cracks and crack-like defects by a number of solid-liquid and solid-state mechanisms before exposure to the service environment. These various effects of welding are considered, with reference to the risk of environment-sensitive frac...