Effects of Gap Width and Cathodic Potential on Stress Corrosion Cracking Susceptibility of X80 Pipeline Steel in NS4 Solution

Slow strain rate test (SSRT) was used to study the effects of gap width and cathodic protection potential on stress corrosion cracking susceptibility of X80 pipeline steel in NS4 solution under simulated peeling coating. The results showed that with the increase of the gap width, the stress corrosion cracking susceptibility of X80 pipeline steel first increased and then decreased, and the highest stress corrosion cracking susceptibility was under the condition of 100 μm gap width. When the gap width was 200 μm, the stress corrosion sensitivity of X80 pipeline steel showed a trend of first decreasing and then increasing with the negative shift of the applied cathodic protection potential. When the cathodic protection potential was -1 100 mV, the high stress corrosion sensitivity was due to the combined effect of cathodic hydrogen evolution and stress.