SCC quick-evaluation model of high-strength pipeline steel in the typical external environment

Stress corrosion cracking (SCC) has always been a crucial issue affecting the safe operation of pipeline steels. To address the challenges of SCC evaluation for pipeline steels in external environments, this study establishes and validates a SCC quick-evaluation model for pipeline steel in external environments. This model requires only electrochemical tests and a small number of slow strain rate test to obtain the stress corrosion susceptibility distribution of pipeline steel across the entire potential range. The model is applicable to different environments and pipelines, demonstrating broad applicability, operational convenience, and accurate results. The evaluation error of the model is less than 18 %, meeting the requirements for SCC assessment in engineering. Based on the quick-evaluation model, non-steady-state electrochemical test provides electrochemical information for crack-tip and non-tip regions at different potentials, serving as the basis for determining SCC mechanisms. As the applied potential shifts negatively from OCP, the SCC mechanisms of pipeline steel can be divided into the AD+HE and HE mechanism.