Alternating Current Corrosion Behaviors of X70 Steel in Neutral Environments

Weight loss tests of X70 steel samples were performed in soil-simulating conditions at various AC current densities from 0 to about 500 A·m-2. The results showed that the corrosion rate increased as AC current density increased. Corrosion induced by AC current can present different types in different electrolyte environments. The uniform corrosion happened on X70 steel surface due to the influence of alternating current in the environment with SO42- and without other aggressive ions. But when Cl- existed, pitting corrosion happened due to the influence of alternating current and Cl-. The corrosion product had certain protection. Because the electrolysis role of alternating current changed the electrolyte resistivity, the alternating current value decreased with the soak time, and the decline feature presents exponential law.