Computational study of the carbon steel corrosion behaviors under alternating current based on the mathematical model

In this paper, an alternating current (AC) corrosion mathematical model consisting of both the current and the potential information was derived based on the equivalent electric circuit. The model was solved numerically. The influences of peak voltage and frequency of the applied AC, Tafel slopes, double layer capacitance, and solution resistance on the corrosion system were studied. It was found that not only the ratio but also the independent value of the anodic and cathodic Tafel slopes is fundamental to the AC corrosion process. The AC-induced corrosion potential shifting direction was determined by the relations between the time-average anodic and cathodic currents versus the direct current (DC) potential. Based on the results, a mechanism was proposed to explain the AC-induced corrosion potential shifting phenomena.