Galvanic corrosion behaviour of GH4169–TC4–7050–GH2132 fastening system in simulated marine atmospheric environment

Galvanic corrosion at dissimilar-metal interfaces can compromise the durability of multi-material fastening systems used in marine atmospheric environments. This study systematically investigates the galvanic corrosion behaviour of a GH4169 bolt–TC4 pedestal–7050 skin–GH2132 nut fastening system in a simulated marine atmosphere under different temperatures and immersion durations. Immersion tests, electrochemical measurements, and finite-element simulations were conducted to clarify the corrosion behaviour of the 7050/GH2132 and TC4/GH4169 galvanic couples. The 7050/GH2132 couple exhibited a large potential difference and developed severe localised corrosion, accompanied by increased corrosion current density, decreased charge transfer resistance, progressive degradation of the Al 2 O 3 -rich surface film and intensified pitting with increasing temperature and immersion time. In comparison, the TC4/GH4169 couple showed a smaller potential difference and limited corrosion evolution because of the relatively stable TiO 2 -rich passive film. The simulations further revealed pronounced corrosion localisation near the 7050/GH2132 interface but negligible morphology evolution in TC4/GH4169. These findings identify the 7050/GH2132 interface as the primary corrosion-sensitive region and provide guidance for corrosion protection of aerospace fastening systems.