The formation mechanism of corrosion scale and electrochemical characteristic of low alloy steel in carbon dioxide-saturated solution

摘要

The formation mechanism of corrosion scale and electrochemical characteristic of low alloy steel in CO_2-saturated solution were investigated by electrochemical measurements and surface characterization. The results show that the electrochemical behavior is associated with the formation of corrosion scale and the microstructure of steel. At the initial polarization stage, ferrite dissolves preferentially and leaves Fe_3C behind, which results in high Fe~(2+) ions concentration between lamellar Fe_3C. This situation facilitates the formation of FeCO_3 scale between the lamellar Fe_3C. With further increase of polarization times, the whole electrode surface is covered by FeCO_3 scale.