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 steels in the near-neutral pH solutions that form in coating disbondments was studied using slow strain rate tests (SSRT), polarization techniques, scanning electron microscopy (SEM), and secondary ion mass spectrometry (SIMS). Results showed hydrogen could diffuse into the steels around the crack tip during the SCC process. Hydrogen facilitated the dissolution rate of the steel in the solution and increased SCC intensity. A mechanism was proposed that showed hydrogen enhances the anodic dissolution type of SCC in dilute aqueous solution. Thermodynamic analysis of the SCC process was consistent with experimental results.