The effect of environmental factors such as HC03+ ion, CH3C00- ion, and Ca2+ ion, and microstructure on morphology of corrosion products was investigated in C02 environments with 0.3MPa CO* at 80”C. Steel J55 with ferritic-pearlitic microstructure and Steel N80 with martensitic microstructure were used as testing materials. Steel J55 showed good localized-corrosion resistance compared with Steel N80. A linear relationship between pH and corrosion rate was obtained in Steel J55 with homogeneous corrosion, but the relationship was not so good in Steel N80 with heterogeneous corrosion.
Kev words: Ferritic-pearlitic microstructure, Martensitic microstructure, Carbon Steel, CO2 corrosion, Corrosion morphology, Oil Country Tubular Goods(OCTG)