Influence of Hydrostatic Pressure on the Corrosion Electrochemistry Behaviors of 2205 Steel in Deep Sea Environment

The corrosion behaviors of unloaded and U-shaped loaded 2205 steel in 3.5% (mass) NaCl solution with different hydrostatic pressure were studied by electrochemical impedance spectroscopy, potentiodynamic polarization and Mott-Schottky method. The morphology and composition of corrosion products of 2205 steel after electrochemical tests were observed and analyzed by SEM and EDS. The results showed that 2205 steel had good pitting resistance in 3.5% NaCl solution. With the increase of hydrostatic pressure, the free corrosion potential decreased, the free corrosion current density increased, and the electrochemical impedance decreased. U-shaped loading could reduce the pitting potential of 2205 steel. The carrier density of passive films formed at 20 MPa was the highest, and the carrier density of passive films formed at constant pressure was the lowest.