Galvanic Corrosion Performance of High-Strength Copper-Nickel Alloys in Seawater

High-strength copper-nickel (Cu-Ni-Mn-Al-Nb) alloys are widely used for marine applications because of their excellent resistance to seawater corrosion, high inherent resistance to biofouling, and ease of fabrication. However, in-service experience has shown that these alloys may encounter variable performance worldwide as a result of local environmental conditions. In particular, the corrosion performance of high-strength Cu-Ni alloys may be affected by the seawater environmental factors, which may include biofouling, temperature, salinity, pH, and dissolved oxygen content. This study reports an investigation into the galvanic corrosion performance between two wrought, high-strength copper-nickel alloys, with nickel contents of 15% and 19%, regarding the influence of surface oxide films/deposits and biofouling. X-ray photoelectron spectroscopy was used to study the composition of the corrosion product films. Analyses of galvanic currents, coupled and decoupled potentials routinely monitored for seawater immersion over a period of 2 years, are presented.