Evolution and characterization of the film formed on super 13Cr stainless steel in CO2-saturated formation water at high temperature

The evolution and characterization of films formed on super 13Cr at 90 °C and 200 °C were investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Focus Ion Beam (FIB) and Transmission Electron Microscopy (TEM) and localized Raman spectroscopy. The results show that super 13Cr maintains a passive state at 90 °C, while an active state exists with a high corrosion rate of 0.43 mm/year at 200 °C for the first 5 h, then stabilizes to a rate of 0.125 mm/year over 5 days exposure. The passive film formed at 90 °C is an amorphous-like structure with high Cr content, while the corrosion product films formed at 200 °C are mainly comprised of nanocrystalline spinel FeCr2O4 and crystalline FeCO3.