ABSTRACT
6061 aluminium alloy matrix composite containing 20.5 vol% particulate alumina and 5052 aluminium alloy were welded using a brake type friction welding machine. The microstructures and mechanical properties of the friction welded joints were investigated. The mechanically mixed regions and the alumina particles which had moved to the other part of the composite alloy were observed clearly on the weld interface. The hardness at the weld interface showed higher values than those of the base metals. The variation of hardness on the composite material side was not very significant, but a softened area could be seen in the heat affected zone of the 5052 aluminium alloy side and recovery to the same level of hardness as that of the 5052 aluminium alloy base metal could be found at about 20 mm from the weld interface. Regardless of the welding conditions, the joint efficiency in terms of tensile strength was 95–101% of that of the composite material base metal and the maximum elongation was 71% of that of the composite material base metal. Friction welded joints with good joint efficiency fractured near the weld interface of the heat affected zone of the composite base metal. The impact values of the welded joints with a notch in the weld interface were about 70% of those of the composite material base metal.
