Durability of CFRP in Marine Environments and Corrosion Acceleration When Galvanically Coupled to Mild Steel

In marine environments， clarifying both the durability of CFRP and its galvanic behavior when coupled with carbon steel is critical for engineering practice. Galvanic interaction accelerates steel corrosion， and CFRP’s long-term performance hinges on the stability of its barrier and interfacial adhesion. In this study， specimens with original surface （OS）， bare surface （BS）， and peel-ply （PPS） surface， as well as cross-sections， underwent water immersion and cyclic-corrosion accelerated ageing. Electrochemical characterization quantified CFRP durability evolution and galvanic acceleration on steel. The results showed that aged CFRP exhibited only mild degradation while retaining a barrier function. Specifically， low-frequency impedance and interfacial charge-transfer resistance decreased without spanning an order of magnitude， whereas the constant-phase element increased and the phase angle decreased； cyclic corrosion was more detrimental than water immersion. An open-circuit potential difference of approximately 800 to 900 mV between steel and CFRP provided a strong driving force for galvanic corrosion. Polarization curves and mixed-potential analysis indicatd that galvanic coupling increased the steel corrosion rate by about 4.6~23.3 times. By reducing fiber exposure and electrical connectivity while preserving a resin-rich layer， PPS surface treatment effectively suppressed galvanic corrosion and enhanced interfacial adhesion， whereas the cross-section was the most vulnerable region to galvanic acceleration.