CO₂ Corrosion Behavior of High-Strength and Toughness V140 Steel for Oil Country Tubular Goods

The CO₂ corrosion behavior of V140 steel for oil country tubular goods exposed to high-temperature and pressure environment was studied by immersion corrosion experiments. The morphology, composition and elemental analysis of corrosion products were conducted by scanning electron microscope, x-ray diffractometer and electron probe micro-analyzer, respectively. The results showed that the corrosion rate gradually decreased and tended to be stable with the extension of corrosion time. The corrosion products in the initial stage were FeOOH and Fe₂O₃, and the final corrosion product was FeCO₃. With the extension of corrosion time, corrosion products gradually became thick and dense from sparse. The fine and dense FeCO₃ layer effectively improved the CO₂ corrosion resistance of V140 steel.