Effect of Dissolved Oxygen on Pitting Resistance of 2205 Duplex Stainless Steel in Hot Concentrated Seawater

The effect of dissolved oxygen concentration on pitting corrosion behavior of 2205 duplex stainless steel in concentrated seawater at 72℃ was studied by cyclic anodic polarization curve and electrochemical impedance spectroscopy (EIS). The results indicate that with the increase of dissolved oxygen concentration from 0.34 mg/L to 3.06 mg/L in seawater, the corrosion potential and pitting potential of 2205 duplex stainless steel increased by about 0.16 V and 0.209 V respectively, the resistance values of passive film and charge transfer process were enhanced greatly. So the passive film became more stable and hard to be destroyed to make pitting corrosion happen in 2205 duplex stainless steel. However, the repassivation potential slightly decreased by about 0.072 V with the increase of dissolved oxygen concentration after pitting corrosion occurred in 2205 duplex stainless steel. The pits grew in a wide potential range and then consumed more electrical charges during the cyclic polarization measurements, which led to the formation of deeper pits.