Corrosion Behavior of Martensite-Based Stainless Steels in Chloride Solutions Saturated with CO₂ Containing Impurity Gases

In Carbon Capture and Storage (CCS), CO₂ is gathered from various CO₂ emitters and injected into underground storage sites. The captured CO₂ contains impurity species such as O₂, SOx and NOx, and the injection tubing will be in contact with formation water, which has a high concentration of chlorine. CO₂ corrosion is a primary concern in the selection of the tubing material. Although martensite-based stainless steels are candidate tubing materials, few reports have examined their corrosion behavior in the presence of high pressure CO₂, and especially CO₂ that contains impurity components. In this document, the corrosion behavior of steels containing 13 % Cr to 17 % Cr was investigated. The corrosion rates of the 13CR steel were higher than the acceptance criterion of 0.127 mm/y, and pitting occurred under most test conditions. The Modified 13CR series showed lower corrosion rates than 13CR. Their corrosion rates were lower than 0.127 mm/y, and the steels were free from pitting under most test conditions. Even under some test conditions in which Mod. 13CR steels suffered pitting, the 15CR and 17CR steels were free from pitting and their corrosion rates were lower than 0.127 mm/y, indicating that 15CR and 17CR have superior corrosion resistance. Martensitic stainless steels can be considered viable candidate materials for injection tubing for CCS, and 15CR and 17CR steels have better corrosion resistance and would be applicable under severer corrosive conditions.