An analysis of electrochemical corrosion on pipeline steel in silty soil under salt-temperature coupling environments

The initial corrosion evolution process of X80 steel exposed to silty soil mixed with NaCl at increasing salinities and temperatures was investigated. Based on the electrochemical testing and microscopic observations, the analysis results indicate dissolution rate is limited by cathodic processes in moist soil. The migration and accumulation of Cl- ions on the oxide film surface are driven by soil water potential after soil freezing, resulting in the decomposition of the film. The release of Fe2+ accelerates the passiva-tion rate. The growth of salt and ice water crystals on the steel-soil interface expands the void between the soil particles, thereby further increasing the diameter of the corrosion pit. (c) 2023 Elsevier Ltd. All rights reserved.