Fundamental understanding on the effect of Cr on corrosion resistance of weathering steel in simulated tropical marine atmosphere

The role of Cr on the corrosion resistance of weathering steel in simulated tropical marine atmosphere was investigated by the dry/wet cyclic corrosion test. The addition of Cr in steel greatly promotes the transformation of α-FeOOH. Cr-doped α-(Fe,Cr)OOH and FeCr2O4 present spherical particles of about ten nanometers, improving the compactness of the rust layer. Cr forms Cr2O3 and Cr(OH)3 with good corrosion resistance, and promotes the enrichment of Cu to form CuO in the inner rust layer. These products increase the nucleation position and effectively refine the rust grains, leading to the increase of diffusion resistance for corrosive species.