Atmospheric corrosion of carbon steels in tropical and subtropical climates in Southern China

Abstract Q235 and Q345 carbon steels were exposed for up to 24 months at three test sites of tropical and subtropical climate. The atmospheric corrosion kinetics of Q235 and Q345 was studied by weight‐loss measurement. The results show that the ranking of the atmospheric corrosivity from weak to strong of the three test sites is Xishuangbanna, Guangzhou, and Wanning. The kinetics of the atmospheric corrosion process presents two stages with an accelerated second stage in marine environments of high chloride ion content and high relative humidity, whereas no second stage appears in the kinetics curves in rural and industrial urban environments. The corrosion acceleration stage in the marine environment of the Wanning site is attributed mainly to the high chloride ion concentration and loose rust layer structure.