Shuji Hashizume

Polarization Behavior of High-Alloy OCTG in CO2 Environment as Affected by Chlorides and Sulfides

Abstract Pitting corrosion resistance of 13% Cr steel, duplex stainless steel, and high Ni austenitic stainless alloys for Oil Country Tubular Goods (OCTG) has been examined by electrochemical meas...

Corrosion Resistance of Martensitic Stainless Steels in Environments Simulating Carbon Dioxide Gas Wells

Abstract Martensitic stainless steels (SS) have been used widely for oil-country tubular goods (OCTG) because of their high strength and excellent corrosion resistance in carbon dioxide (CO2) gas wells. Cr-rich precipitates form after tempering heat treatments of martensitic SS. These precipitates can affect the corrosion resistance of martensitic SS in environments simulating CO2 gas wells because Cr is considered to be an important element for improving corrosion resistance. The effects of chemical composition and tempering heat treatments on corrosion rates and pitting potentials were investigated to clarify the effect of precipitates on corrosion resistance of martensitic SS in environments simulating CO2 gas wells. The general corrosion index (GCI = Cr − 12 C + 0.77 Ni + 10 N [mass %]) was confirmed as a good index for estimating corrosion rates of martensitic SS in environments simulating CO2 gas wells. The term “C coefficient/Cr coefficient” (−12), was defined as the amount of Cras carbide precipit...