Influence of Clsup>- on Corrosion Behavior of Galvanized Auto Steel Sheet in Mud

Corrosion behavior of the galvanized auto steel sheet and the substrate in the mud containing different contents of Cl- was investigated and compared by the immersion test,electrochemical impedance spectroscopy (EIS) analysis and SEM observation.Under the experimental conditions apparent corrosion for both materials have took place and the corrosion rate of the galvanized steel sheet was normally higher than that of the substrate.The content of Cl- in the mud had a significant effect on the corrosion behavior,the highest corrosion rate for the galvanized steel sheet was in the 5% Cl- mud and for the substrate in the 1% Cl- mud,respectively.The compactness of corrosion products decided their protection property and the Cl- ions affected the corrosion behavior of metals through influencing the dissolved oxygen in the mud and the protection property of corrosion products.The analysis results of corrosion potential and EIS were quite consistent with the corrosion rates,reflecting the change of electrode properties with time during corrosion.