Compared to the conventional Rankine steam cycle, the Brayton cycle system utilizing supercritical carbon dioxide (S-CO₂) as the working fluid offers significant advantages, including higher energy conversion efficiency, a more compact structure, enhanced safety, economic benefits, and a superior overall energy efficiency ratio. Consequently, the S-CO₂ Brayton cycle system holds promise for application in thermal power generation, fourth-generation nuclear power, new gas turbines, solar power generation, and other fields. In various operating conditions, material corrosion in high-temperature CO₂ environments has consistently been identified as a primary factor leading to the degradation of superheaters and reheaters. The corrosion mechanisms of steel in CO₂, particularly the differences between ferritic and austenitic steels, are not yet fully understood. T92 ferritic steel and 316L austenitic steel are widely recognized as preferred materials and have been extensively utilized as superheater/reheater components in power stations. Enamel coating has been considered a cost-effective solution for enhancing the oxidation resistance of steels without considerably degrading their mechanical properties. Therefore, this work investigated the corrosion behaviors of T92 ferritic steel and 316L austenitic steel, and enamel-coated steels in CO₂ at 600 ^oC. Results revealed rapid oxidation and carbon invasion for both T92 and 316L steels, with 316L austenitic steel exhibiting superior oxidation resistance and slightly better carbon invasion resistance due to its higher chromium content. Meanwhile, the mass gain after 500 h of corrosion was significantly higher for T92 ferritic steel than for 316L austenitic steel, reaching 10.51 and 1.38 mg/cm², respectively. The oxidation kinetics of all samples follows an approximately parabolic trend. A double-layered structure comprising an outer Fe-rich oxide layer and an inner Cr-rich oxide layer is formed on the surface of both steels. The interface between the inward growth of the inner layer and outward growth of the outer oxide layer corresponds to the initial steel surface. In addition, rapid carbon invasion and carburization cause more metal damage than oxidation. While T92 ferritic steel and 316L austenitic steel exhibited comparable resistance to carbon invasion, differences in their structures led to variations in carbide distribution within the steels. T92 ferritic steel demonstrated homogeneous carbide formation due to its high internal diffusion channel density, resulting in an intrusion depth of 329 μm after 500 h of corrosion. In contrast, carbides primarily precipitated at the austenitic grain boundaries of 316L austenitic steel, extending up to 241 μm within the same corrosion timeframe. Enamel-coated samples exhibited excellent corrosion resistance by effectively inhibiting oxidation and carburization reactions through isolating the contact between CO₂ and the steels. Consequently, the corrosion mass gain in these samples was reduced by at least two orders of magnitude. Furthermore, the glass phase of the enamel maintained thermal stability throughout the corrosion process, while the strong bond between the enamel coating and substrate provided long-term protection against thermal stress effects.