Corrosion susceptibility of dissimilar friction stir welds of AA5083 and AA6082 alloys

The corrosion susceptibility of dissimilar friction stir welds of AA5083-O and AA6082-T6 alloys has been investigated. Two different tool traverse speeds were compared, revealing that the faster welding speed resulted in increased susceptibility to corrosion because of the reduced tool rotation rate per weld length for heat generation and mixing of materials. The heat affected zones of both alloys and the transition regions between the AA5083-O and the AA6082-T6 rich zones have been identified to be the regions that are most susceptible to corrosion. Grain boundary sensitization in the heat affected zones of both alloys, distribution of Mg2Si particles along the boundary between the two alloys (in the thermomechanically affected zones of the welds) and the galvanic interactions between the AA5083 rich zones and the AA6082 rich zones were observed to be responsible for the corrosion susceptibility in the welds.