Corrosion resistance and mechanism of new type Cu-Cr-Ni seawater corrosion-resistant steel

A new type of corrosion-resistant steel (B-NS) for ship hull was developed by adding alloying elements Cu, Cr and Ni according to the corrosion characteristics of marine environment. The corrosion resistance of B-NS was investigated by electrochemical test, full immersion test and dry-wet cyclic test, and the cross-sectional morphology and composition of the rust layer were analyzed by scanning electron microscope and energy dispersive spectroscopy. The results show that the addition of alloying elements effectively reduces the saturated current density and corrosion rate of B-NS steel under full immersion and dry-wet cyclic test. The alloying elements promote the formation of a more stable and dense protective rust layer under dry-wet cyclic test. The alloying elements give B-NS ship plate steel excellent corrosion resistance mainly in improving the thermodynamic stability of B-NS ship plate steel, promoting the formation of rust layer to prevent aggressive media from corroding the substrate, and giving the rust layer cation-selective permeability to prevent Cl- from penetrating into the rust layer.