缝隙宽度和外加阴极保护电位对NS4溶液中X80管线钢应力腐蚀敏感性的影响

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

采用慢应变速率试验(SSRT)研究了缝隙宽度和阴极保护电位对模拟剥离涂层下NS4溶液中X80管线钢的应力腐蚀敏感性的影响。结果表明:随着缝隙宽度的增加,X80管线钢的应力腐蚀敏感性呈先增大后减小的趋势,其在100μm缝隙宽度条件下的应力腐蚀敏感性最高;缝隙宽度为200μm时,随阴极保护电位的负移,X80管线钢的应力腐蚀敏感性呈先降低后升高的趋势;阴极保护电位为-1100 mV时,X80管线钢的应力腐蚀敏感性较高是阴极析氢和应力的共同作用导致的。

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.