An electrochemical and X-ray computed tomography investigation of the effect of temperature on CO₂ corrosion of 1Cr carbon steel

This paper presents the investigation on the effect of temperature on the corrosion behavior of 1Cr carbon steel at 40 °C and 80 °C in 1 wt. % NaCl aqueous solution saturated with CO₂. The evolution of the corrosion process was followed with Linear Polarization Resistance (LPR) and Electrochemical Impedance Spectroscopy (EIS). X-ray Computed Tomography was used for 3D structure of the scale ex-situ to correlate with electrochemical investigation. Additionally, the surface morphology of the corrosion products was analyzed with Scanning Electron Microscopy (SEM) and structural information using X-ray powder diffraction (XRD). Tomography results showed protective FeCO₃ formation with three different layers at 80 °C, where corrosion underneath the scale was uniform. The 3D image of the corrosion products formed at 40 °C showed loose and porous, and consequently did not reduce the corrosion rate unlike for 80 °C. Low temperature test also showed signs of localized corrosion beneath the corrosion products.