Effect of alternating current on stress corrosion cracking behavior and mechanism of X80 pipeline steel in near-neutral solution

The influence of alternating current (AC) density on stress corrosion cracking (SCC)behavior and the mechanism of X80 pipeline steel was investigated in NS4 near-neutral solution by slow strain rate tensile tests (SSRT), surface analysis techniques, data acquisition technique, and electrochemical measurements. Results showed that the SCC susceptibility of X80 pipeline steel was improved with the increasing of AC density, and the SCC mechanism was collectively controlled by anodic dissolution (AD) and hydrogen embrittlement (HE). When the AC density was below 10 A m−2, the corrosion enhanced because of a vibrating effect. However, when the AC density was no less than 30 A m−2, SCC susceptibility enhanced because of the hydrogen evolution reaction. With regard to potential acquisition, only a very small percentage about 1.5%-2% of AC was involved acting as faradaic current, which resulted in hydrogen evolution reaction and then improved the SCC susceptibility.