Role of microstructures on stress corrosion cracking of pipeline steels incarbonate-bicarbonate solution

Stress corrosion cracking (SCC) on the external surface of pipelines contri butes to the major failure of pipelines. The great majority of SCC is inter granular and occurs in a carbonate-bicarbonate environment. Metallurgical f actors affecting SCC are still vague and therefore have been studied. Unifo rm microstructures, not mixed structures, are favorable for suppressing SCC . Low-C steels produced In a process such as thermomechanical-controlled pr ocessing are less susceptible to SCC. The presence of locally soft microstr uctures decreases resistance to SCC (mixed structure and decarburized struc ture). However, SCC resistance is high on hard layers, like grit-blasted su rfaces.