Synergistic effect of AC and Cl^- on corrosion behavior of X80 pipeline steel in alkaline environment

The influence of AC on the corrosion behavior of X80 pipeline steel was investigated in chloride-containing alkaline environment by electrochemical measurements and immersion tests. The results show that a superimposed AC degrades the passivity of the steel, shifts the corrosion potential negatively, and increases the corrosion rate. Both the increasing AC current density and the concentration of chloride ion accelerate the corrosion of the steel. With the addition of 0.2 M Cl^- to the solution, AC and Cl^- generate synergistic effect on the corrosion behavior of the pipeline steel, especially, the corrosion rate greatly increases and corrosion becomes more localized.