Influence of pre-oxidation on the corrosion behavior of weathering steel

Abstract

Atmospheric corrosion of steels is an electrochemical process resulting in heavy losses each year. This work mainly focused on corrosion behavior of pre-oxidized weathering steels. The steels in four surface states, i.e., ground by 150# silicon carbide, polishing, phosphating and ZnO coating, were oxidized at 400°C or 700°C for different time under different oxygen content. The results indicated that the polishing specimens had lowest corrosion rate, compact oxide structure and good adherence to the corrosion products. The oxides were composed of Fe2O3, Fe3O4 and Fe, while corrosion products were composed of Fe3O4, α-FeOOH, β-FeOOH and γ-FeOOH. Under the condition of different oxygen content, pre-oxidized weathering steels in reduced oxygen content relative to open air produces more obvious Cr element enrichment in the inner rust layer close to the substrate.