Effect of chromium content in steel on its corrosion resistance in carbon dioxide environments

The corrosion resistance of steels containing 3–17% Cr in media with high partial pressure of CO₂ and varying temperature and salinity was studied. The general corrosion rate and the characteristics of local corrosion were determined gravimetrically. The structure and composition of corrosion products were analyzed using scanning electron microscopy. The results indicate that resistance to CO₂ corrosion increases with chromium content and that a Cr concentration of 3–5% is insufficient to keep the general corrosion rate below 0.1 mm/year. At temperatures above 120 °C, steels with 15–17% Cr exhibit the highest resistance to CO₂ corrosion. The transition of CO₂ to supercritical state does not significantly accelerate the corrosion of steels containing 13% Cr or more, under otherwise identical conditions.