交流杂散电流密度对X80管线钢腐蚀行为的影响

Effects of AC Stray Current Density on Corrosion Behavior of X80 Pipeline Steel

采用自主设计的试验装置,通过电化学试验和浸泡试验对不同交流杂散电流密度下X80管线钢的腐蚀行为进行了研究。结果表明:交流干扰对X80管线钢阴极极化的影响程度远大于对其阳极极化的影响,在产物膜的形成速率与溶解速率相差不大时,极化曲线表现为两个零电流电位;交流杂散电流密度较高时,最大蚀坑深度显著增加,X80管线钢的腐蚀形态由均匀腐蚀向点蚀转变;交流杂散电流密度大于100A/m2时,用局部腐蚀速率评价X80管线钢的腐蚀程度更合理。

The corrosion behavior of X80 pipeline steel at different AC stray current densities was studied by electrochemical test and immersion test with self-designed test equipment.The results show that the effect of alternating current（AC）interference on the cathodic polarization was more than on the anodic polarization for X80 pipeline steel.When the formation rate of the corrosion scale was close to its dissolution rate,there were two values of free corrosion potential in the polarization curve.With the continuous increase of AC stray current density,the maximum depth of corrosion pit increased significantly,and corrosion form gradually changed from uniform corrosion to pitting corrosion.When AC stray current density was more than 100 A/m^2,it was more reasonable to use the localized corrosion rate as the evaluation indicator for corrosion of X80 pipeline steel.