Stress corrosion cracking of ultrahigh strength martensite steel Cr9Ni5MoCo14 in 3.5% NaCl solution

This paper describes the stress corrosion cracking (SCC) mechanism of a new structural ultrahigh strength martensite steel Cr9Ni5MoCo14 and how cathodic potential affects the SCC susceptibility in 3.5% NaCl solution. At open circuit potential (OCP), SCC cracks initiate from pittings, and SCC mechanism involves anodic dissolution. Within the ideal cathodic protective potential range from −500 mV−500 mV to −700 mV−700 mV, the specimen has a greater SCC resistance, and SCC mechanism is mixed-controlled by both anodic dissolution and hydrogen-induced cracking. Significant hydrogen-induced crack is observed at −1100 mV−1100 mV which can be attributed to a significant amount of hydrogen atoms involving in the cracking processes.