Hydrogen-facilitated anodic dissolution-type stress corrosion cracking of pipeline steels in near-neutral pH solution

The effect of hydrogen on stress corrosion cracking (SCC) of pipeline steel s in the near-neutral pH solutions that form in coating disbondments was st udied using slow strain rate tests (SSRT), polarization techniques, scannin g electron microscopy (SEM), and secondary ion mass spectrometry (SIMS). Re sults showed hydrogen could diffuse into the steels around the crack tip du ring the SCC process. Hydrogen facilitated the dissolution rate of the stee l in the solution and increased SCC intensity. A mechanism was proposed tha t showed hydrogen enhances the anodic dissolution type of SCC in dilute aqu eous solution. Thermodynamic analysis of the SCC process was consistent wit h experimental results.