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Abstract
Friction stir welding (FSW) has been performed to produce similar commercial pure aluminum specimens as well as dissimilar joints of commercial pure aluminum and Al-Si-Mg alloy. The main objective of the work is to study the effect of the tool geometry and dimensions, tool rotational and welding (progress) speeds on the mechanical properties and microstructure of the weld nugget (bead).
Specimens have been made with length 200 mm, thickness of 10 mm, and width of 40 mm. In the case of silicon – magnesium – aluminum alloy, same dimensions as in the first set, but the thickness were 7 mm. The tensile specimens manufactured to study the tensile properties of the welded parts, were machined according to DIN 50125.
The FSW were welded in a direction parallel to the rolling direction of the delivered material. Before welding, the edges to be welded were cleaned and adjusted to be parallel to each other.
The FSW operations were carried out using a universal milling machine which has a maximum spindle rotational speed of 1500 rpm, and maximum feed of 26 mm/min. A special fixture was designed and constructed in order to achieve clamping and fixing the welded parts edges in contact. The clamping system was used also to overcome the high welding forces. The used tools were made of high-speed steel (HSS) to satisfy the weld parameters.
The mechanical properties of the welded joints are investigated and the maximum resistance (Rm), hardness, the macro and micro structures of the friction stir welded specimens are studied as well.
Through changing the stir welding parameters, some sound specimens and other defected ones were obtained. The optimum parameters to obtain sound joints, and better mechanical properties were determined.