Carbon capture, utilization and storage (CCUS) is a critical technology for reducing atmospheric greenhouse gas emissions by capturing carbon dioxide (CO₂) emissions from industrial sources and transporting them for utilization or long-term geological storage. However, the captured CO₂ often contains reactive impurities that can accelerate corrosion in transport and storage infrastructure. In particular, water (H₂O) and nitrogen dioxide (NO₂) readily react to form nitric acid, creating highly aggressive corrosion conditions. While the CO₂ is often transported in the supercritical state, pressure reductions at end-use or storage sites can induce phase separation and water condensation. These locations create multi-phase conditions where acid formation and corrosion becomes a concern and emphasizes the need for proper material selection in these areas. This study investigates the initial corrosion behavior of five steels under simulated end-site conditions. Electrochemical corrosion testing in a 0.001 M HNO₃ (100 ppmv NO₂) solution continuously bubbled with CO₂ was performed on X80, 2Cr, 5Cr, P91, and 316L steels using open circuit potential, linear polarization resistance, and potentiodynamic polarization techniques. The chromium (Cr) content of the steels was found to highly influence corrosion resistance with increasing Cr content, reducing the resulting corrosion rate. Overall, X80 had the highest corrosion rate of 0.6 mm/yr, whereas 316L had the lowest corrosion rate of 0.005 mm/yr. Additionally, low Cr steels, particularly 2Cr, displayed unstable corrosion product formation in the linear polarization tests, indicating that small amounts of Cr may be insufficient for proper corrosion protection. The results show that higher-Cr-content steels are better suited for phase-transition regions along CCUS chains. Proper material selection at these critical locations is therefore essential to ensure long-term operational safety and reliability along the CCUS chain.