An evaluation of the resistance of pipeline steels to initiation and early growth of stress corrosion cracks

Safety and reliability are basic requirements on the operation of systems of high-pressure pipelines. One of the dangerous mechanisms endangering the safe operation is stress corrosion cracking (SCC). In this work, SCC initiation in two types of pipeline steels––a carbon pipeline steel and an X60 high-strength thermo-mechanically treated steel––in carbonate solution was studied. An influence of surface microstructure, different stress/strain conditions and temperature was evaluated. The X60 steel was more sensitive to the SCC process in comparison with the carbon steel. Surface local microscopical inhomogeneities were the predominant initiation sites of microcracks.