Oxygen Transport Modeling for Atmospheric Corrosion of Carbon Steel in Cold Region

Atmospheric corrosion of carbon steel in cold regions remains insufficiently understood, particularly under winter conditions characterized by low temperatures combined with high airborne sea salt deposition. This gap necessitates a mechanistically based predictive model. This study developed a concise mathematical model based on outdoor exposure tests to describe the atmospheric corrosion of carbon steel in cold regions, with a focus on oxygen transport. Despite the cold climate, the corrosion rates increased in winter owing to increased airborne sea salt levels and the formation of thicker aqueous salt solution layers. The corrosion rate increased proportionally with the fourth root of the solution-layer thickness. Numerical analyses conducted using the finite element method suggest that oxygen transport processes, including dissolution from the gas phase, influence the corrosion behavior under thin NaCl solution layers. The corrosion rates calculated from solution layer thicknesses using weekly, monthly, seasonal, and/or annual averages of airborne sea salt deposition and relative humidity showed good agreement with the measured values. These results demonstrate the applicability of the proposed simplified model for predicting the corrosion lifetime of carbon steel in cold regions, within the assumptions adopted in this study.