The Effect of Chloride on Stress Corrosion Cracking of X100 Pipeline Steel in Carbonate/Bicarbonate Solution

In this paper, the stress corrosion cracking (SCC) behaviors of X100 pipeline steel are studied in a carbonate/bicarbonate solution with different concentrations of chloride (Cl⁻) by using slow stress-strain tests, electrochemical measurements, x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The effect of Cl⁻ on the SCC process is discussed based on the change of surface state and the force of crack propagation. The results showed that the SCC susceptibility of the steel increased with the rise of Cl⁻ concentration. Cl⁻ promoted the SCC process by providing a high driving force for crack propagation and accelerating anodic dissolution. Furthermore, Cl⁻ reduced the FeCO₃ content in the film on the steel surface, which facilitated the initiation of SCC.