Prediction and Verification of Galvanic Corrosion of 7B04 Aluminum Alloy Under Simulated Marine Environment

Based on the principle of corrosion electrochemistry and the finite element method, the galvanic corrosion models for 7B04 aluminum alloy with CFRP, TA15 titanium alloy and 30CrMnSiA steel in the simulated marine environment were established respectively. The distribution of the galvanic potential and the galvanic current density on the electrode surface were obtained. The galvanic corrosion current was measured and was used to verify the accuracy of the prediction models built at present. The corrosion potential of the four materials can be arranged from high to low as E_CFRP > E_TA15 > E_30CrMnSiA > E_7B04, and the 7B04 aluminum alloy is accelerated to corrode as anode after coupling. The galvanic potential of different galvanic systems has little difference but the galvanic current changes obviously. The galvanic current of the coupling between 7B04 and CFRP is the largest when the area ratio is the same. This indicates that their couple effect is the strongest. The second is between 7B04 and TA15 and the weakest is between 7B04 and 30CrMnSiA. The galvanic potential and the galvanic current between the cathode and anode increase linearly with the increase of the ratio of the cathode/anode area. The relative error between the calculated results and the predicted results is less than 5%, indicating that the dual electrode galvanic corrosion model in the electrolyte has a higher prediction accuracy.