Corrosion behavior of X80 pipeline steel under thin electrolyte layer of acidic soil simulated solution

Abstract

Corrosion behavior of X80 steel under thin electrolyte layer (TEL) of acidic soil simulated solution were studied by utilizing polarization curves, EIS, SEM and XRD. In the bulk solution, cathodic electrochemical reaction governed the corrosion process of X80 steel, and the corrosion rate was higher. Under TEL, the corrosion of X80 steel was greatly affected by TEL thickness. Under TEL of 300 μm, the corrosion was still related to the cathodic electrochemical process. Under TEL of 145 μm, oxygen diffusion dominated the corrosion process, and the corrosion rate fluctuated with immersion time. However, the corrosion of X80 steel was jointly affected by the diffusion processes of oxygen and corrosion products under TEL of 70 μm. In this system, the corrosion rate increased continuously. After 96 h exposure, the corrosion extent of steel with TEL thickness was in the sequence of 70 μm > 300 μm > 145 μm. Complete corrosion product layer was easier to form in the thinner TEL.