Influences of water content on the corrosion behavior of X70 steel in Dagang saline-alkaline soil

The corrosion behavior of X70 steel in Dagang saline-alkaline soil with 20%-34% water content was studied by polarization curve measurement and electrochemical impedance spectroscopy (EIS). It is shown that the corrosion behavior of X70 steel is strongly dependent on the water content in soil. Local corrosion occurred at the water content of 25%, and general corrosion took place when the water content was more than 30%. With increasing water content, the corrosion current density increased to a maximum at the water content of 25% and then decreased. The low-frequency inductance loop emerged at the water content of 20%. It disappeared with increasing water content and a single capacitive impedance loop was observed.