Al 2 O 3 -fortifed AA6061-T6 joint produced via friction stir welding: The effects of traveling speed on microstructure, mechanical, and wear properties

In this study, 6 mm thick AA6061-T6 alloy was friction stir-welded at different traveling speeds while Al 2 O 3 nano-particles were incorporated between adjoining plates. All joints were investigated macro- and micro-structurally. In addition, distribution pattern of Al 2 O 3 nano-particles in the stir zone was observed via scanning electron microscopes. Although the specimen friction stir-welded at 40 mm/min exhibited the most homogeneous particles distribution, friction stir welding at 1600 rpm and 45 mm/min yielded highest tensile strength. Fractographs achieved from tensile test specimens were in close agreement with corresponding percent elongations. Surprisingly, the foregoing specimen exhibited inferior hardness to the as-received AA6061-T6 alloy. Accordingly, it was concluded that dissolution of strengthening precipitates dominated the effect of hard reinforcement particles on enhancement of hardness value. As a result of Al 2 O 3 nano-particles introduction, on the other hand, wear resistance improved tremendously.