Ex‐situ synchrotron X‐ray diffraction study of CO2 corrosion‐induced surface scales developed in low‐alloy steel with different initial microstructure

The CO2 corrosion-induced scale developed in the surface region of the low-grade carbon steel is thoroughly investigated to understand the corrosion mechanisms involved during exposure to CO2-saturated aqueous environments. In this work, in addition to the electron microscopy and lab-source X-ray diffraction (XRD) methods, ex-situ depth-resolved phase identification of the corrosion scales developed on steel with different initial microstructures is performed using synchrotron grazing incidence XRD at different incidence angles. The CO2 corrosion mechanism is discussed considering the observed distribution of the corrosion products formed at a different depth relative to the time of electrochemical exposure of the steels.