Effect of sulphur dioxide on the corrosion of a low alloy steel in simulated coastal industrial atmosphere

• Effect of SO2 on steel corrosion in coastal-industrial atmosphere was studied.
• Increasing SO2 content does not always lead to a higher corrosion rate.
• Effect of SO2 is not obvious in early atmospheric corrosion of steel.
• The corrosion evolution of steel in coastal-industrial atmosphere was discussed.

This investigation aims to study the effect of SO2 on the corrosion of a low alloy steel in simulated coastal industrial atmospheres. The results indicate that the corrosion weight gain of the steel firstly increases with increasing SO2 content to a certain level and then decreases with further increasing the SO2 content. Besides, higher SO2 content promotes the formation of α-FeOOH and inhibits the formation of γ-FeOOH. Moreover, it seems that the deterioration effect of SO2 to steel corrosion is not obvious in the initial corrosion stage and SO2 begins to accelerate the steel corrosion as the corrosion process increases.