Hydrostatic Pressure Induces Corrosion Cracking of 2205 Duplex Stainless Steel in an Oxygen‐Free Deep‐Sea Environment

Hydrostatic pressure and dissolved oxygen may vary among different marine water bodies; in this work, corrosion behaviors of 2205 DSS in 3.5 wt% NaCl solution with different hydrostatic pressure and dissolved oxygen were studied. EIS, PC, and MS curves were used to study the electrochemical properties. Corrosion surfaces were studied by SEM‐EDS. Based on the EBSD technique, the cracks on the corroded surface were analyzed, and the corrosion products were characterized by XPS. The results show that the high hydrostatic pressure reduces corrosion resistance, while dissolved oxygen enhances it. Oxygen reduction requires a higher activation energy in a deep‐sea environment than in a shallow sea, and the cathode process changes from oxygen evolution reaction to hydrogen evolution reaction as the hydrostatic pressure increases under the solution with dissolved oxygen. Dissolved oxygen prevents hydrogen‐induced cracks in deep‐sea due to the oxide film. Hydrostatic pressure induces corrosion cracking of 2205 DSS in a 3.5 wt% NaCl solution with oxygen‐free conditions, and the crack develops at the grain boundary in the ferrite phase, especially at the long grain boundaries of the large ferrite grain.