Effect of initial CaCO3 saturation levels on the CO2 corrosion of 1Cr carbon steel

This paper presents the investigation on the effect of calcium on the corrosion behavior of 1Cr carbon steel under various levels of initial CaCO₃ saturation () of the bulk solutions. All the experiments were performed at 80°C in 1 wt% aqueous NaCl solution saturated with CO₂. Four initial levels were investigated, namely 0, 0.6, 2, and 10. The corrosion process was followed using linear polarization resistance, potentiodynamic sweeps, and electrochemical impedance spectroscopy. The surface morphology of the corrosion products was analyzed with scanning electron microscopy and structural information using X-ray powder diffraction. Precipitation of a substitutional solid solution of Fe_xCa_yCO₃ (x + y = 1) was found on the steel surface. The growth of this layer was delayed by Ca²⁺ ions in the solution, but its protectiveness was not affected and was comparable with the pure FeCO₃ corrosion product. No signs of localized corrosion were detected on the material.