Research on Atmospheric Corrosion of 45# Steel in Low-Latitude Coastal Areas of China

Abstract

Urgent action is required to mitigate the severe corrosion of carbon steel in low-latitude regions. The combination of high humidity, temperature, and salinity in these areas significantly accelerates steel corrosion, posing a substantial threat to the service safety of offshore engineering equipment. This study aims to elucidate the atmospheric corrosion mechanisms of 45# steel in low-latitude coastal areas. Samples of 45# steel were exposed to atmospheric conditions over various durations in the following three geographically distinct regions: Guangzhou, Wanning, and the South China Sea. The corrosion rates were calculated using weight loss tracking and potentiodynamic polarization measurements, while surface corrosion products were examined using X-ray diffraction (XRD) tests. The findings indicate a clear correlation between the corrosion rate of 45# steel and the latitude and specific location of the test area, with the highest to lowest rates observed in the South China Sea, Wanning, and Guangzhou, respectively. Similarly, the extent of corrosion rust penetration in defective coatings followed the same order. Moreover, the protection ability index (PAI) calculations revealed that none of the tested samples formed a protective corrosion film.