Corrosion behavior of 60Si2MnA spring steel in mixed salt environments

Abstract The atmospheric corrosion behavior of 60Si2MnA spring steel was investigated in environments containing chloride (Cl − ) and sulfate (SO 4 2− ). Bare steel specimens were exposed to controlled laboratory conditions that replicated key parameters of the target atmosphere. The deliquescence and weathering characteristics of the deposited salts were examined using electrochemical impedance spectroscopy, while a custom-built salt deposition system was employed to conduct corrosion tests at constant temperature and humidity (20 °C/75 % RH and 40 °C/75 % RH) with a surface salt load of 10 g/m 2 over varying exposure durations. Pronounced corrosion was observed under both temperature conditions. X-ray diffraction and Raman spectroscopy revealed that the corrosion products were primarily composed of iron oxyhydroxides and iron oxides. Scanning electron microscopy combined with electrochemical analyses showed that, at early exposure stages, the rust layer exhibited abundant cracks and pores, allowing for the ingress of corrosive species. The initial corrosion products acted as strong oxidants, enhancing cathodic reactions and thus accelerating metal degradation. With increasing exposure time, the thickening of the rust layer provided partial protection, slightly improving the corrosion resistance. Elevated temperature was found to significantly accelerate both the corrosion rate and the evolution of corrosion products.