Difference in corrosion behavior of pure iron and carbon steel in short-time exposure test

Corrosion behavior of pure iron and carbon steel in short-time exposure test was examined in detail by electrochemical methods. Though the corrosion resistant of pure iron was better than that of carbon steel in the initial stage of exposure test, the amount of corrosion losses for pure iron was more than that for carbon steel after 6 month-exposure test. From the results of ESCA analysis and various electrochemical measurements, it was found that the oxide film formed on pure iron in the initial stage of exposure test was more stable and difficult to be attacked by chloride ions than that formed on carbon steel. On the other hand, after 6 month-exposure test, it was indicated that the amount of γ-FeOOH that was reduced to magnetite easily was abounding in the rust of the pure iron in comparison with that of the carbon steel.