The corrosion behavior of the welded joints of copper pipe in artificial seawater was studied with anodic polarization

electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM).Experiment results indicated that the anodic processes of copper

cupronickel-welded joint and brass-welded joint were similar in artificial seawater.At the same electrode potential

the corrosion current of cupronickel was the lowest and the corrosion resistance was the best

which is consistent with the EIS result.The current density peak of brass welded line appeared at -0.012 V

and a porous corrosion film was formed.The electrode was passivated subsequently.The passivation film was made up of Cu2O，CuCl and ZnO.The passivation film dissolved with electrode potential

and displacement deposition took place between Cu and Zn.The copper redeposition on the electrode surface induced the increase of electrode activity and corrosion rate.At an electrode potential of +0.87 V

the electrode surface was rich of acicular Sn and stannum oxide.This film would prevent the electrode from dezincification

and the current density decreased and homeostasis was reached at the same time.The corrosion mechanism of brass welded line in artificial seawater was dissolution/redeposition.