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

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/m², it was more reasonable to use the localized corrosion rate as the evaluation indicator for corrosion of X80 pipeline steel.