Understanding the Corrosion Behavior of P92 Steel in CO₂ Using In Situ Monitoring Technology I: Mechanism of Carbon Migration and Transformation

Carbon migration and subsurface transformation, among the corrosion processes of P92 steel in high-temperature CO₂ were investigated using in situ monitoring technology. During monitoring reaction intermediate CO was used to distinguish between the oxidation and carbonization reactions. The CO generation rate on P92 steel at 550 °C and 600 °C reached the highest value after 80 min and 100 min, respectively. Honeycomb pores in Fe₃O₄ oxide scale were observed as the main channels for CO₂ and CO gas diffusion and carbon deposition. The deposited carbon gradually diffused into the matrix in an ionic state and transformed into carbides.