Influence of Chromium Content in Alloys on Corrosion in Saline Water Saturated with Supercritical CO2

Amid growing global efforts toward carbon capture, utilization, and storage (CCUS), this study investigates the influence of chromium (Cr) content in candidate construction alloys on their corrosion modes and kinetics in supercritical CO2 (s-CO2)-saturated saline water at 8 MPa and 50 °C. The results indicate that alloys with a Cr concentration of over approximately 9 wt.%, including P91, 316L, and Alloy 800, exhibit a satisfactory corrosion performance in this environment. During exposure to s-CO2-saturated saline water, a non-protective FeCO3 layer forms on all tested alloys. For alloys containing more than 2 wt.% Cr, an inner Cr-enriched layer concurrently grows and acts as a barrier to resist environmental attack. The integrity of the inner and outer corrosion layers becomes more compact and uniform on alloys with at least 9 wt.% Cr. Pitting is unlikely to occur on candidate alloys used for s-CO2 storage or enhanced oil recovery.