The effect of Cr and Mo on the corrosion behavior of high strength steel was investigated in CO2/H2S environments. Corrosion tests were conducted using three different types of steel; Base steel (including no Cr and no Mo), 1% Cr steel and 1% Mo steel, in 1 wt.% NaCl solution (80°C) at initial pH 5.7 and initial pH 4.2 under atmospheric pressure. The test solution was saturated with flowing CO2/10% H2S mixture. Changes in corrosion rate with exposure time were monitored by linear polarization resistance (LPR) measurements. The surface morphology and the composition of the corrosion product layers were analyzed by various surface analysis techniques (SEM, EDS, EPMA, and XRD). The results showed that the final corrosion rates for all three steels were low (less than 0.2 mm/y) due to the formation of protective FeS layer. However, the initial corrosion behaviors were different among the three steel types depending on the role of corrosion products including Cr and Mo.

Subject
Scanning electron microscopy, X-ray diffraction, Steel surfaces, Corrosion rate, Iron sulfides, Acidity, Corrosion products, Surface analysis, Corrosion behavior, Surface layers, Steel, Linear polarization resistance, Samples
Keywords:
CO2/H2S corrosion, high strength steel, alloying element, FeS
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2020
Association for Materials Protection and Performance (AMPP)
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