Long term corrosion of X70 steel and iron in humid supercritical CO2 with SO2 and O2 impurities

Abstract

The corrosion of X70 steel and iron in supercritical CO₂/SO₂/O₂/H₂O environment were investigated after a 454 h exposure. Optical microscopy was applied to observe the morphology of etch pits and synthesise the three-dimensional morphology. X-ray diffraction and X-ray photoelectron spectroscopy were employed to detect the composition of product scales. Experimental results verified that the localised corrosion occurred on the X70 steel sample under corrosion product deposits. Ferrous sulphate, sulphur and iron sulphide were detected as the corrosion products.