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

• Published in: Corrosion science Vol. 222; p. 111387
• Main Authors: Haratian, Saber, Gupta, Kapil Kumar, Larsson, Alfred, Abbondanza, Giuseppe, Bartawi, Emad Hasan, Carlà, Francesco, Lundgren, Edvin, Ambat, Rajan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2023
• Subjects: Chemical Sciences; CO corrosion; CO2 corrosion; Depth-resolved phase identification; Grazing incidence X-ray diffraction; Kemi; Materialkemi; Materials Chemistry; Natural Sciences; Naturvetenskap; Scaling; Grazing incidence X-ray diffraction; Scaling; CO2 corrosion; Depth-resolved phase identification
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2023.111387

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. [Display omitted] •Mode of corrosion propagation affects scale composition, distribution & morphology.•Corrosion scale morphology depends on the initial steel microstructure.•Variation in local pH atop different micro-regions forms differential scale.•Higher local pH within cementite lamellas accelerates mixed carbonate precipitation.•Vertical interfaces in corrosion scale causes higher ionic permeability.