The environmental conditions encountered in oil and gas wells can cause severe corrosion to mild steel tubing and pipelines and the microstructure and chemical composition of steel are considered to be important variables that affect the resistance of steel to corrosion. Five different pipeline steels with different chemical composition and microstructure were chosen to investigate the effect of their metallurgy on the properties of iron carbonate and related corrosion phenomena that could lead to localized corrosion. The effect of a high liquid flow rate on a pre-formed iron carbonate corrosion product layer was studied at 80°C, pH 6.6, and 1.5 pCO2. Iron carbonate layer, initially pre-formed on each steel at relatively low wall shear stress (35 Pa), was then exposed to high wall shear stress (535 Pa) for 3 days. For all tested steels, the pre-formed iron carbonate layer reduced the general corrosion rate to less than 0.5 mm/y after 2 days, but the increase in wall shear stress caused partial loss of the protective iron carbonate layer. All steels suffered localized or pitting corrosion, but the penetration rates of pitting found in normalized steels was much lower than that of quenched and tempered steels.
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Akeer et al. (2013) studied this question.