Alternating Current Corrosion Behavior of X80 Steel in 0.5 mol/L NaHCO3 Solution

The corrosion behavior of X80 steel in solution of 0.5 mol/L NaHCO3 with alternating current was investigated by polarization curves,electrochemical impedance spectroscopy (EIS),optical microscopy,etc. The results show that: as AC current density increased,the polarization curve of X80 in NaHCO3 solution presented alternating passivation characteristics at anode and little change at cathode,and the EIS showed a character of capacitive arc and Warburg impedance,implying a diffusion-controlled reaction process;X80 steel surface suffered pitting firstly and then expanded to an uniform corrosion,and its corrosion product was a mixture of iron oxides,iron or calcium carbonate,et al.