Role of cementite morphology on corrosion layer formation of high-strength carbon steels in sweet and sour environments

Abstract

The effect of cementite morphology on the corrosion layer formation of four high-strength carbon steels was studied in an aqueous solution containing CO2 and CO2/H2S. The linear polarization resistance and weight loss data reveal that as the cementite phase fraction is increased, the corrosion rate increases in CO2 environment, while no trend is observed in the CO2/H2S environment. The results indicate that a porous and, non protective corrosion layer forms in the CO2 environment, whereas a protective layer forms in the CO2/H2S environment. A mechanism that explains the role of cementite morphology on corrosion layer formation in a CO2 environment is proposed for the studied materials.