Effect of O₂ on Corrosion Behavior of L80-13Cr Stainless Steel in Water Injection Well Environment

The influence of O₂ on the corrosion behavior of L80-13Cr in water injection well environments was studied using immersion corrosion test combined with electrochemical testing analysis. The results show that the average corrosion rates of both oxygen containing and non oxygen containing environments are similar, and the maximum pitting rate in oxygen containing environment is larger and the surface pitting pits are deeper. When there is O₂ in the solution, some loose and porous FeOOH and Fe₃O₄ appear in the passive film composition, and uneven coarse calcium carbonate rod like grains are distributed on the surface, which is easy to form an oxygen concentration cell, thus intensifying the local corrosion of L80-13Cr steel. The presence of O₂ increase the self corrosion current density of 13Cr, and oxygen absorption corrosion replaces the depolarization reaction of hydrogen as the main cathodic reaction, thus accelerating the anodic reaction. Moreover, the resistance value of the passive film R_f and the charge transfer resistance R_ct of the metal substrate/film interface after 7 d corrosion are both lower than those in the oxygen free environment. The passive film in the oxygen containing environment has poor protection ability and weak self-healing ability, and is prone to steady-state pitting corrosion.