Atmospheric corrosion behavior of Nb- and Sb-added weathering steels exposed to the South China Sea

The atmospheric corrosion behavior of new-type weathering steels (WSs) was comparatively studied, and the effects of Nb and Sb during corrosion were clarified in detail through field exposure and characterization. The results showed that the addition of Nb and Sb played positive roles in corrosion resistance, but there was a clear difference between these two elements. Nb addition slightly improved the rust property of conventional WS but could not inhibit the electrochemical process. In contrast, Sb addition significantly improved the corrosion resistance from the aspects of electrochemistry and rust layer. Compared with only 0.06wt% Nb, the combination of 0.05wt% Sb and 0.06wt% Nb could better optimize the rust structure, accelerate the formation of a high proportion of dense and protective α-FeOOH, repel the invasion of Cl⁻, and retard the localized acidification at the bottom of the pit.