Corrosion Characteristics of 2205 Duplex Stainless Steel in High Temperature and High Pressure Environment Containing H2S/CO2

Abstract

The corrosion characteristics of 2205 duplex stainless steel in high- temperature and high-pressure (HT and HP) environments containing H2S/CO2 are investigated in this paper. After corroded 720 hours in the condition of 3.5 MPa H2S, 3.5 MPa CO2, 205°C, 15% NaCl and a sulfide content of 3g/L, one layer of comparably thick corrosion product are formed on the surface of the specimens. The corrosion products, which are relatively porous, lose its protection to the matrix. Lots of pitting are found on the surface of the steel and intercrystalline fracture and transcrystalline fracture are generated in the bottom of the pitting, which indicates its high sensitivity to stress corrosion crack (SSC). Also, the phenomenon of selective corrosion, a priority corrosion of α phase and minor corrosion or non-corrosion of γ phase, is observed after the corrosion process.