Temperature dependence of carbon deposits within oxide scale on CrMoV steel in atmospheric and supercritical CO2

Abstract CrMoV steel was exposed to 500, 550, and 600 °C for up to 120 h in 0.1 and 10 MPa CO2. A significant change in carbon deposition content was not observed in the 0.1 MPa CO2, in contrast to the high carbon content at 550 °C and 10 MPa CO2. The formation of internal Fe-rich M3C carbides and super saturation of steel grains with dissolves carbon at 550 °C but not at 500 and 600 °C may be responsible for this difference. The effect of carbon deposition on the outward Fe diffusion via vacancy or interstitial sites was also discussed.