Optimizing the nickel content in weathering steels to enhance their corrosion resistance in acidic atmospheres

The effect of nickel on the corrosion resistance of weathering steels in acidic atmospheres was investigated by exposure test and electrochemical technique. The results showed that 3.5 wt.% is the optimum nickel content in weathering steels to enhance their atmospheric corrosion resistance. The reason is discussed as follows: once the nickel content exceeds 3.5 wt.%, the nickel content in the rust increases slightly even with a considerable increase of that in weathering steels; the mass ratio of α-FeOOH to γ-FeOOH in the rust almost remains stable; additional nickel has no significant effect on the corrosion current density of the steels.