Numerical and Experimental Investigation on the Corrosion Resistance of the Coupled 7025 Aluminum Alloy Structure with 304 Stainless Steel Fasteners for Marine Application

This study investigates the galvanic corrosion of AA7025 aluminum alloy coupled with 304L stainless steel (SS) fasteners in marine structures, using a multi-methodological approach involving analytical modeling, SolidWorks 3D modeling, COMSOL Multiphysics simulations, and experimental validation. The AA7025-304L SS couples were tested in tap water, 3.5% NaCl, and 1M H₂SO₄ for 30 days. Corrosion rates increased significantly due to galvanic coupling: 4.92× in tap water, 3.16× in NaCl, and 4.26× in H₂SO₄, with predictive models accurate within 5% error. H₂SO₄ caused the highest hardness loss (10.97%) and a corrosion depth of 100.4 µm. Microstructural analysis showed CaCO₃ scaling in tap water, severe pitting in NaCl, and generalized dissolution in H₂SO₄. COMSOL simulations identified an Al-5Zn sacrificial anode as an effective mitigation strategy, providing a protective current density of 0.84 A/m² and a polarization potential of -1.08 V, significantly reducing AA7025 corrosion in marine-relevant environments.