Studying the STA effects on aluminium alloy joints by friction welding

This article examines the properties of joints fabricated by friction welding (FW) using AA6061-T6 and AA7075 as examples of both similar and dissimilar metals. It also looks at how heat treatment after welding affects the metallurgical characteristics of the joint. The heat treatment method under investigation combines solutionizing heat treatment with synthetic ageing (STA). The tensile characteristics, microhardness, and microstructure of the as-welded and STA-treated welded specimens are assessed in the paper using mechanical testing equipment and metallurgical characterization methods. The findings demonstrate that the joint characteristics are enhanced by precipitate nucleation occurring in the joint interface of the FW similar and dissimilar joint under STA treatment. On the other hand, the STA influence on the tensile strength (TS) of joints made with AA7075 was greater than that of similar joints made with AA6061-T6, as well as dissimilar joints made with both AA6061-T6 and AA7075. Additionally, after STA treatment, the similar joints showed a uniform distribution of hardness. However, in the dissimilar joint after STA treatment, the hardness dropped suddenly on the AA6061-T6 side, specifically from the partially deformed zone (PDZ) towards the heat affected zone (HAZ).