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.