Friction stir welding is advance joining process for different similar and dissimilar metals. It is commonly used for joining of Aluminium alloys. In this study an attempt were made to join commercial structuralaluminium with 7039 aluminium alloy. A zig-zag pattern of hardness was found in weld nugget. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters ontensile properties of friction stir welded joints were analyzed. The results showed that the optimum parameters to get a maximum of tensile strength were 635 rev/min, 12 mm/min and, where the maximum of tensile elongation was obtained at 635 rev/min, 8 mm/min after post weld heat treatment. All welds were failed outside of weld nugget in low strength alloy side. The tensile strength of welds was decreases after post weld heat treatment.

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Friction stir welding Mechanical Properties 7039 Al alloy