Galvanic corrosion performance of high strength copper-nickel alloys in seawater

Description/Abstract

High strength copper-nickel (Cu-Ni-Mn-Al-Nb) alloys are widely used for marine applications due to 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 due to 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.