In the oil and gas industry and CO₂ storage applications, aqueous CO₂ corrosion is one of the most common deterioration mechanisms for the materials utilized for production tubings. Deeper well explorations and future CO₂ storage will exacerbate the situation, demanding the exploitation of novel materials with higher resistance against corrosion. It has been demonstrated in the literature that metallurgical characteristics of materials, such as initial microstructure and the alloying elemental constituents, could considerably affect the CO₂ corrosion mechanisms as well as the material's resistance to further dissolution. As a result, metallurgical factors in material selection are considered to be the decisive parameters in this case. The effect of material characteristics on CO₂ corrosion behavior of steels, and how the precipitation of corrosion products could influence the protectiveness of the underlying material, has been extensively studied in the recent decades. However, only a few studies have attempted to mechanistically undrestand the impact of the initial steel microstructure and Cr content on corrosion behavior of low-alloy steels in CO₂-saturated sweet environments under realistic conditions, such as aqueous formation water chemistry in high-pressure flowing conditions.

The thorough investigations conducted in this work are aimed at determining the impact of metallurgical factors on CO₂ corrosion resistance and the growth of corrosion scale in the low-grade steel's surface region. L80-1Cr steels were austenisized and then subjected to various heat treatments to achieve varied initial microstructures. The as-received L80 material with different Cr content and heat-treated L80-1Cr specimens were then electrochemically exposed to CO₂-saturated simulated formation water chemistry in the dynamic flowing condition. The corrosion behavior of samples was determined by understanding the electrochemical behavior of the steel using both DC and AC techniques as depicted in figure 1. Surface characterizations before and after corrosion experiments were assessed using scanning electron microscopy and lab-source X-ray Diffraction. The CO₂ corrosion mechanism is comprehensively discussed in light of the materials’ electrochemical response, morphology, and the microstructure of the corrosion scale developed on the surface of steels.