Roles of Copper and Nickel in 13%Cr Stainless Steel for Improvement of Wet Carbon Dioxide Corrosion Resistance

Abstract Resistance to hydrogen sulfide (H2S) and carbon dioxide (CO2) corrosion in 13%Cr stainless steel (SS) has been studied to develop a new material in an application field of oil country tubular goods (OCTG). Recently, the combined addition of copper and nickel was found to increase the corrosion resistance of 13%Cr SS under wet, high-temperature, and CO2 environments. The purpose of the present work was to make clear the role of such copper and nickel elements as additive elements to the 13%Cr SS. With the increase in the addition of copper and nickel to the steel, a thickness of corrosion film growing in the immersion test decreased drastically, and the corrosion rate reached < 0.1 mm/y, even at 200°C. The transmission electron microscope analysis revealed that the thin corrosion film was an amorphous phase, and that the addition of copper caused the change of the corrosion film structure from a spinel crystalline to the amorphous one. Nano-ordered segregation of copper at the interface between th...