Understanding the galvanic interactions between AA2024T3 and mild steel using the scanning vibrating electrode technique

Abstract

The scanning vibrating electrode technique has been used to characterize the galvanic interactions between AA2024T3 and mild steel at room temperature and elevated solution temperatures up to 60 °C in naturally aerated 3.5% NaCl solution. The work shows that from a solution temperature of 43 °C and above, highly localised anodic activities with high intensities occur on the mild steel, compared with the anodic activities occurring on the AA2024T3 alloy in a couple system of the two alloys. The highly localised activities on the mild steel were not observed at 34±1 °C with the surface showing no distinct corrosion activities and AA2024T3 alloy was completely the bulk anodic material at this solution temperature. At room temperature, AA2024T3 was also the bulk anode, although mild anodic activities were detected on the surface of the mild steel alloy. The local corrosion activities revealed by the scanning vibrating electrode technique were in agreement with the micrographs of the surfaces of the alloys after the immersion tests.