Characterization of Corrosion Behavior and Corrosion Production Property of 90-10 Cupronickel Welding Joints in Flowing Seawater

Due to its excellent performance, 90-10 cupronickel has been widely used as a pipeline for marine engineering. However, due to the harsh service conditions of flowing seawater, the problem of corrosion leakage is extremely serious. One of the most common locations is the welding joint. In this paper, electrochemical impedance spectroscopy, surface morphology analysis techniques (scanning electron spectroscopy, energy disperse spectroscopy, three-dimensional microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy) are used to study the corrosion resistance of 90-10 cupronickel (MZ), heat affected zone (HAZ) and welding zone (WZ). The experimental results show that MZ, HAZ and WZ can form protective corrosion product film in flowing seawater, and that the corrosion resistance increases with the experiment time increasing and achieves the maximum value after 20 days. However, the corrosion resistance of HAZ is smallest due to the low adhesion density of corrosion production formed on HAZ. HAZ is preferentially corroded for minimum corrosion resistance and galvanic corrosion between WZ and HAZ.