Stress Corrosion Cracking of Simulated Weld Heat-Affected Zone on X100 Pipeline Steel in Carbonate/Bicarbonate Solution

The stress corrosion cracking (SCC) of a simulated weld heat-affected zone (HAZ) in X100 pipeline steel in a carbonate/bicarbonate solution was studied at the open-circuit potential (OCP) and various cathodic potentials. Microstructure of the weld HAZ was simulated by Gleeble processing. Results showed that the steel had a higher sensitivity to SCC at the OCP than at the cathodic potentials. Moreover, the SCC process at - 850 mV was controlled by both anodic dissolution and hydrogen embrittlement (HE), while the SCC was due to HE at - 1200 mV. The SCC occurred at the intercritical HAZ at the cathodic potential because of its lower strength than that of the other weld areas. The fracture modes at the cathodic potentials were all intergranular and transgranular.