In situ synchrotron X-ray diffraction study of the effect of microstructure and boundary layer conditions on CO2 corrosion of pipeline steels

This study demonstrates that the nucleation of crystalline scales of siderite and chukanovite onto the surface of low-alloy steels under CO2 corrosion at elevated temperature is critically dependent on initial surface roughness, on microstructure-related surface roughness developed during corrosion, and on stirring in the solution. This study confirms that effects due to chromium micro-alloying in the steel are extremely important for siderite nucleation. On average, these effects dominate over the effects of microstructure. However, spatial variation of the corrosion deposit thickness indicates an interdependence between microstructure and chromium-enhanced siderite nucleation with the possibility of localised corrosion developing as a result.