Investigating the mechanism of stress corrosion cracking in near-neutral and high pH environments for API 5L X52 steel

• SCC of X52 steel in near-neutral and high pH solution was studied.
• The dominant mechanism was anodic dissolution at low applied cathodic potential.
• The dominant mechanism was hydrogen embrittlement at high cathodic potential.
• Anodic dissolution is active at typical potential ranges of cathodic protection.
• The X52 shows higher susceptibility to near-neural pH SCC up to −1100 mVAg/AgCl.

Stress corrosion cracking behaviour of API-5L-X52 steel under cathodic protection in near-neutral and high pH conditions was studied using slow strain rate test method and electrochemical measurements. The slow strain rate test showed ductile and brittle fracture feature at low and high applied potentials, respectively. In order to identify the mechanism contributes in stress corrosion cracking; the electrochemical potentiodynamic polarisation test was done at fast and slow sweep rate. The results revealed that at near-neutral pH condition the anodic dissolution at crack tip was the dominant mechanism. While at high pH medium, the hydrogen based mechanism was dominant.