Corrosion study of the friction stir lap joint of AA7050-T76511 on AA2024-T3 using the scanning vibrating electrode technique

• Friction stir lap welds of AA7050-T76511 with AA2024-T3 pit preferentially on AA7050 nugget zone.
• Intergranular attack (IC) is deeper on the AA2024 heat affected zone (HAZ).
• Due to galvanic coupling IC attack on AA2024 HAZ is less pronounced than on parent AA2024-T3 alloy.

The corrosion of dissimilar friction stir (FSW) lap welded AA7050-T76511 and AA2024-T3 Al-alloys has been investigated using scanning vibrating electrode technique (SVET) in 0.1 M NaCl solution. FSW lowers the repassivation potential of the more active AA7050, while its pitting potential remains unaffected. For longer exposures at OCP pitting occurs preferentially on AA7050-nugget zone (NZ) close to the AA7050–AA2024-interface, due to the local galvanic coupling, as well as to the higher stability of pits nucleated on the AA7050-NZ. AA2024 heat-affected zone (HAZ) is the most intergranular corrosion (IC) susceptible region. However, IC-attack is less intense than on parent AA2024-T3 alloy.