Electrochemical behavior of 2205 duplex stainless steel in simulated solution containing high concentration Cl^- and saturated CO₂ at different temperatures

2205 duplex stainless steel (DSS) has good corrosion resistance due to its typical duplex organization, but the increasingly harsh CO₂-containing oil and gas environment leads to different degrees of corrosion, especially pitting corrosion, which seriously threatens the safety and reliability of oil and gas development. In this paper, the effect of temperature on the corrosion behavior of 2205 DSS in a simulated solution containing 100 g/L Cl^- and saturated CO₂ was investigated with immersion tests and electrochemical tests and combined with characterization techniques such as laser confocal microscopy and X-ray photoelectron spectroscopy. The results show that the average critical pitting temperature of 2205 DSS was 66.9 °C. When the temperature was higher than 66.9 °C, the pitting breakdown potential, passivation interval, and self-corrosion potential decreased, while the dimensional passivation current density increased, and the pitting sensitivity was enhanced. With a further increase in temperature, the capacitive arc radius of 2205 DSS decreased, the film resistance and charge transfer resistance gradually decreased, the carrier density of the donor and acceptor in the product film layer with n + p bipolar characteristics also increased and the inner layer of the film with Cr oxide content decreased, while the outer layer with Fe oxide content increased, the dissolution of the film layer increased, the stability decreased, and the number and pore size of pits increased.