Atmospheric Corrosion Behavior of Weathering Steel in Periodically Changed Environment

Abstract

The service environments of weathering steel are periodically various. However, the general accelerated corrosion test cannot effectively simulate the periodic change. In order to investigate the influence of periodic changed environments on corrosion, a low alloy weathering steel was exposed to an indoor air with NaCl and NaHSO3 aqueous solutions spraying the steel in turns. It was found that both atmospheric corrosion rate and the degree of alloy element enrichment in the inner rust layer were higher when the samples were sprayed with NaCl aqueous solution. Meanwhile, more compact rust layers were formed when the samples were sprayed with NaHSO3 aqueous solution. Rust layer would stabilize more rapidly by spraying NaCl and NaHSO3 aqueous solutions in turns than by spraying a single corrosion solution, which can be attributed to a combined advantage of alloy element enrichment and slow corrosion. Stabilization of rust layer is not necessarily derived from enrichment of alloy elements and stabilization of rust layer can produce stronger effect against further corrosion than enrichment of alloy elements.