Effect of Temperature and Oxygen Concentration on Corrosion of J55 Steel in an O₂/CO₂ Environment

ABSTRACT The corrosion product competition and transformation process of J55 under an O 2 /CO 2 environment in the temperature range of 50–350°C and 0–1 MPa oxygen partial pressure range, respectively, were studied using electrochemical and surface analysis techniques as well as thermodynamic calculations to determine its corrosion rate change law and pitting corrosion phenomenon. This study demonstrates that the uniform corrosion rate of J55 with increasing temperature shows a trend of first increasing, then decreasing, and finally increasing. The transformation of its corrosion products, from FeCO 3 into Fe 3 O 4 , is consistent with the altering corrosion rate law with increasing temperatures. J55 corrodes faster at 350°C as the O 2 partial pressure increases. When the O 2 partial pressure is low, the predominant kind of corrosion product that is obtained is FeCO 3 ; when the O 2 partial pressure exceeds 0.2 MPa, all corrosion products are transformed into iron oxides. As the oxygen partial pressure increases, J55's corrosion product film becomes increasingly less protective of the substrate, making the substance more vulnerable to corrosion reactions.