Galvanically Induced Intergranular Corrosion of AA5083-H131 Under Atmospheric Exposure Conditions: Part 2—Modeling of the Damage Distribution Available to Purchase

In this second in a series of two papers, a computational model to predict intergranular corrosion (IGC) damage caused by galvanic interactions between aluminum alloy (AA)5083 (UNS A95083) and AISI 4340 (UNS G43400) steel is presented. This model calculates the potential distribution based on the tertiary current distribution calculated from the Laplace equation using experimentally derived electrochemical boundary conditions. The potential distribution so derived was used to predict IGC depth after 100 h in solutions of different sodium chloride (NaCl) concentrations and compared to the experimental data presented in Part 1. The model calculations show good agreement with the results from exposure tests over a range of atmospheric conditions. The ability to predict the damage after 100 h using potential distributions calculated without considering any time dependencies, including homogeneous reactions, implies that the ohmic drop associated with the atmospheric exposure condition is of greater importance than changes in thin solution layer chemistry for this system. The influences of the degree of sensitization, relative humidity, and salt loading density on IGC propagation can be described by the model. The assumptions and limitations of the current model are also discussed.