Comparison of corrosion behaviors of low‐alloy steel exposed to vapor‐saturated H₂S/CO₂ and H₂S/CO₂‐saturated brine environments

Abstract

In this paper, immersion experiments were carried out to compare corrosion behaviors of low‐alloy steel exposed to both H2S/CO2 environments in terms of corrosion kinetics, corrosion products, macroscopic/microscopic surface morphology, cross‐section morphology, and elemental distribution. The experimental results demonstrated that the corrosion kinetics of both the corrosion environments was similar. The distinctive corrosion environment accelerated the formation of different corrosion products. The corrosion products of vapor‐saturated H2S/CO2 environment were mackinawite, cubic iron sulfide, and greigite, while, the ones of H2S/CO2‐saturated brine environment were mackinawite and cubic iron sulfide. The surface formation process was also similar. The vapor‐saturated H2S/CO2 environment promoted the formation of fine crystals compared with H2S/CO2‐saturated brine environment. Molybdenum accumulated in the inner layer in both the corrosion environments. Two schematic models of corrosion process are proposed based on the experimental data.

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