Effect of Local Corrosion Caused by Inclusions and Surface Scratches of Steel in High Temperature and Pressure Flue Gas Environment

By simulating the high temperature and high pressure flue gas environment in heavy oil thermal recovery, the influence of two kinds of surface defects, steel inclusions and surface scratches, on local corrosion of steel was studied. And the mechanism of local corrosion caused by inclusions and surface scratches was analysed steel #20 and 26CrMo4 were used as experimental materials, and reacted in a 9 MPa flue gas environment for 24h. The reaction temperatures were 120 °C and 250 °C. The results show that the non-metallic inclusions in the steel are weak parts of the passivation film on the surface of the sample and are easily corroded by corrosive media. The scratched area is more likely to cause aggregation of corrosive media than other parts of the steel surface, and the iron elements in the metal in this area are more likely to reach the surface and react with the corrosive medium.