Corrosion behavior and mechanism of 3Cr steel in CO2 environment with various Ca2+ concentration

The effect of Ca2+ on the corrosion behavior of 3Cr steel was investigated using immersion tests and electrochemical measurements. The results demonstrated that with an increase in Ca2+ concentration in the solution, the corrosion rate of 3Cr steel decreased and the Ca2+ content in the corrosion scale increased. Ca is involved in the formation of both the inner and outer corrosion scales of 3Cr steel. Polarization curves revealed that Ca2+ could enhance the pseudopassivation of 3Cr steel. EIS results demonstrated that Ca2+ can decrease the porosity of corrosion films. Additionally, Ca2+ could accelerate the precipitation of FeCO3 (CaxFe1−xCO3) by reducing its solubility and saturation degree.