Observations of stress corrosion cracking in pipeline steel in corrosive seawater environment including detailed observation of the crack initiation mechanism

The effect of stress concentration on crack initiation and propagation during stress corrosion cracking of carbon steel in alternate wet and dry marine condition was studied by constant load tensile and microelectrochemical test. Results showed that the notch front does not crack but pitting occurs in the corrosion process under load-free condition. Under the loading condition, the anodic dissolution (AD) near the notch gradually intensified, and this effect become severer with increasing load. The local environment of the load-induced rapid AD and hydrogen evolution (HE) can lead to crack initiation, indicating that the joint action of AD and HE is the main SCC mechanism.