Corrosion resistance of martensitic stainless steel OCTG in severe corrosion environments

摘要

The corrosion resistance of martensitic stainless steel at a high CO_2 and simulated acidizing condition was studied. Modified 13Cr steels and new 15Cr steel show good corrosion resistance at the very high CO_2 environment of 160oC and 50 MPa CO_2. Martensitic stainless steels showed high corrosion rate in the live acid condition, but those corrosion rates were lower than 22Cr duplex stainless steel. No localized corrosion was observed in martensitic stainless steels, but selective dissolution was observed between austenite and ferrite in 22Cr duplex stainless steels. The corrosion rate of new 15Cr in the spent acid condition was the lowest in these steels. The martensitic stainless steels showed better corrosion resistance than 22Cr duplex stainless steel in the inhibitor containing conditions. New 15Cr showed good corrosion resistance in the high CO_2 environment and acidizing condition.