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

Stress corrosion cracking (SCC) on the external surface of pipelines contributes to the major failure of pipelines. The great majority of SCC is intergranular and occurs in a carbonate-bicarbonate environment. Metallurgical factors affecting SCC are still vague and therefore have been studied. Uniform microstructures, not mixed structures, are favorable for suppressing SCC. Low-C steels produced In a process such as thermomechanical-controlled processing are less susceptible to SCC. The presence of locally soft microstructures decreases resistance to SCC (mixed structure and decarburized structure). However, SCC resistance is high on hard layers, like grit-blasted surfaces.