A study on the interaction between chloride ions and CO2 towards carbon steel corrosion

•An interaction mechanism between of Cl− and CO2 on the carbon steel corrosion exists.•The relaxation process of water-iron species appears for the CO2 saturated solutions.•Cl− contributes to the decrease of surface coverage of corrosion products and film breakdown. This article addresses the knowledge gap in the area of the interaction between Cl− and CO2 on carbon steel pipelines by comprehensively evaluating the corrosion behaviour of AISI 1020 carbon steel exposed to solutions containing Cl− and/or CO2 over time periods between 0.5 and 72 h at 60 °C. The results show Cl− can reduce the surface coverage percentage of corrosion products and contributes greatly to film breakdown. The carbon steel is thus exposed to the corrosive solution containing CO2 species, accelerating the further propagation of corrosion pits.