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在模拟近中性p H土壤腐蚀环境的NS4溶液中,采用慢应变速率拉伸(SSRT)试验、电化学极化和SEM观察,研究了外加阴极极化电位对X80管线钢近中性p H土壤应力腐蚀开裂(SCC)行为的影响。结果表明:X80管线钢在近中性p H土壤环境中SCC敏感性较高,开裂模式为穿晶SCC;SCC机制随外加阴极极化电位不同而改变,外加阴极极化电位高于-900 m V时,SCC受阳极溶解和氢脆混合控制,外加阴极极化电位低于-900 m V时,SCC为氢脆控制;随着外加电位负向增加,慢拉伸试样的断面收缩率、延伸率和断裂时间降低,SCC敏感性增加,在实际管道阴极保护工程中要避免过保护。
In NS4 solution simulating the soil pH of near-neutral p H, SSRT, electrochemical polarization and SEM were used to study the effect of cathodic polarization on the near neutral p H Effect of soil stress corrosion cracking (SCC) behavior. The results show that the SCC sensitivity of X80 pipeline steel is higher in near-neutral p H soil environment and the cracking mode is transcrystallization SCC. The mechanism of SCC changes with the increase of cathodic polarization potentials, and the cathodic polarization potential is higher than -900 m SCC was controlled by anodic dissolution and hydrogen embrittlement. When the cathodic polarization potential was lower than -900 mV, SCC was controlled by hydrogen embrittlement. With the increase of negative applied potential, the reduction of area of slow tensile specimen, Elongation and fracture time decreased SCC increased sensitivity in the actual pipeline cathodic protection project to avoid over-protection.