Substitution of Ni with Cu and Its Impact on the Corrosion Resistance of Ni-Advanced Weathering Steels in the Simulated Tropical Marine Atmosphere

The effect of substituting equal concentrations of Ni with 0.7 wt% and 1 wt% Cu on the corrosion behavior of Ni-advanced weathering steels (WS) in the simulated tropical marine atmosphere was studied. The results reveal that the effect of substituting Ni with Cu on enhancing the corrosion resistance of Ni-advanced WS is positively correlated with the substitution of Cu, as the concentration of Cu substitution affects the synergistic effect of Cu/Ni in Ni-advanced WS. With the substitution content of 0.7 wt% Cu, the synergy effect of Cu/Ni on enhancing the densification and protection of the rust layer is weakened which promotes the charge transfer process and accelerates the corrosion process of Ni-advanced WS. As the content of Cu substituting Ni increases up to 1 wt%, the synergy effect of Cu/Ni is stronger than that of Ni at the same content. Consequently, modifies the Ni-depleted region in the rust layer, the alpha-FeOOH content in the rust layer is increased, makes the rust layer dense, and intensifies the charge transfer resistance at the substrate-rust interface, thereby improving the corrosion resistance of the Ni-advanced WS.