Improving aluminium-steel bolted joint durability in marine environments via computational galvanic corrosion studies

This study couples transient ISO 11997-1 cyclic salt-spray modelling with laboratory tests to assess galvanic corrosion of bolted A4 stainless-steel/EN AW-6082 assemblies. A time-dependent electrolyte-film thickness and conductivity model was coupled to a galvanic-corrosion solver to quantify how washer electrochemistry and geometry affect galvanic currents and corresponding mass loss. Washer open-circuit potential E corr and exchange current density i 0 are primary controls: more noble washers or higher i 0 drive larger cathodic currents, especially in thin films. Design should keep the aluminium potential below the pitting potential E pit via low-activity or insulating washers, geometric adjustments, or insulating/coating treatments. Simulations show nylon washers reduce predicted mass loss by ≈65 %, with a further ≈32 % reduction when washer diameter is increased by 8 mm. Geometry optimisation can reduce currents and mass loss up to threefold.