Influence of a small velocity variation on the evolution of the corrosion products and corrosion behaviour of super 13Cr SS in a geothermal CO2 containing environment

The general and localised corrosion of super 13Cr SS under various CO2 partial pressures (pCO2) in the static conditions and rotated speeds of 188 rpm at 200 °C were evaluated. The results show that super 13Cr SS exhibits lower localised corrosion risk at 188 rpm compared to the static conditions. The small velocity retards the localised corrosion through the formation of uniform corrosion product scales, which mainly comprises nanocrystalline FeCr2O4 at 2.7 bar pCO2. A double-layered film consists of an inner layer of Cr(OH)3/undissolved austenite and an outer crystalline FeCO3 layer was observed at 28.5 bar pCO2.