No abstract

In this paper, the effects of process parameters, such as the tool rotational and traverse speeds, on temperature evolution and the microstructural and mechanical properties of dissimilar friction stir welding between 3 mm thick AA 7075 aluminum alloy and polycarbonate (PC) plates were investigated. The tool rotational and traverse speeds were varied from 3000 to 3500 rpm and 50 to 150 mm min−1, respectively. The joint fabricated at 3250 rpm and 100 mm min−1 yielded a highest tensile load of 586 N. Microstructural analysis of the stir zone revealed an interlock phenomenon, the transportation of AA 7075 in polycarbonate, and the absence of ceramic-type (carbide, hydride or oxide) compounds. Microhardness (HV) measurement on the weld zone showed an uneven distribution due to the complicated microstructure of the welded joint. The maximum temperatures of 164°C and 66°C were obtained at 3250 rpm and 100 mm min−1 at a distance of 5 mm away from the welding centerline in the AA 7075 and PC side, respectively.

Joining of dissimilar materials, especially in the case of polymer and metal, is significantly challenging because of the difference in chemical, mechanical and thermal properties of the materials. In this paper, a feasibility study of dissimilar materials joint between 7075 aluminium alloy and polycarbonate sheet was conducted by using friction stir welding through butt joint. A series of friction stir welding experiments were executed at various levels in order to obtain good joint. The preliminary results indicated that 7075 aluminium alloy and polycarbonate sheet were successfully joined with the aid of frictional heat energy originated from the friction stir welding process. The formation of 7075 aluminium alloy dislocation at the polycarbonate sheet side was clearly observed at the welding interface, which believed to be contributing to the weld strength. The effects of traverse and spindle speed on weld properties as well as the effect of appearance at joint interface are discussed in the paper.