Corrosion Behavior of T2 and B30 Cu-Ni Alloy at Different Seawater Depths of the South China Sea

Through marine natural environment tests, the corrosion behavior of T2 and B30 Cu-Ni alloy at different seawater depths of the South China Sea was studied. The corrosion morphology and corrosion product properties were investigated using different techniques, including 3D optical microscope, scanning electron microscope (SEM), x-ray diffraction analyzer (XRD) and electrochemical impedance spectroscopy (EIS). Based on the environmental factor monitoring data and corrosion rate data, environmental factor influence mechanism on corrosion behavior was discussed The results indicated that the corrosion rate of T2 decreased with seawater depths increasing, while it was opposite for that of B30 Cu-Ni alloy. The evolution law of the corrosion rates of T2 at different seawater depths was mainly controlled by changes in seawater temperature and dissolved oxygen concentration. The effect of hydrostatic pressure was limited on T2 corrosion rate, but high hydrostatic pressure could promote Cl− penetrating into the corrosion product film, forming a uniform corrosion morphology for T2. For B30 Cu-Ni alloy, it was simultaneously affected by dissolved oxygen concentration and hydrostatic pressure, and the corrosion product film was rich in Ni and Fe elements.