Corrosion Behavior of X60 Steel in CO₂ Environment at High Temperature and High Pressure

The corrosion characteristics of X60 steel at three high temperatures and in the environment of CO2 at 2MPa partial pressure were investigated in autoclave by weight loss evaluation along with SEM,XRD and electron-probe micro-analysis.The results showed that at 90 ℃,120 ℃ and 150 ℃,the steel was attacked seriously by the CO2 and exhibited rather high corrosion rate.With the temperature increasing,the corrosion rate showed a peak,and the maximum rate appeared at 120 ℃.The main corrosion scale consisted of Fe3C and FeCO3.In the experimental process,the features of localized corrosion was presented,i.e.pitting corrosion and strip corrosion.Cl- was the excitant to pitting corrosion.The CO2 corrosion was affected by a series of factors including temperature,corrosion product scale,microstructure of steel,and Cl- ,etc.