الفهرس 
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Abstract
The wide use of aluminum alloys in various applications such as aerospace, high speed train, automotive industries and Spot welds are formed in friction stir spot welding (FSSW) by pressing a rotating tool press against the upper surface of the lap joint of two sheets.
In the present work, the same sheet thickness and different sheet thickness of AA6082, AA2024 and AA1050 were welded using FSSW at a different dwell time and different rotation speeds. The load was noted by using force meter and recorded. The produced joints were investigated by macrostructure and microstructure examination. Bonding shear test and microhardness measurements were conducted on the resultant joints. The fracture surfaces were examined using a scanning electron microscope (SEM). The macro examination showed that defect free spot welded joints were produced at a wide range of rotation speeds. Also there is some defects in the welds of 2024 with 2024, The microstructural results in terms of grain refining of the stir zone (SZ) of the joints insure the mechanical properties of FSSW joints. The fracture stress of 6082-T6/6082-T6 FSSW joints reached the strength of base metal. FSSW of three sheets was successful. The fracture surface investigation revealed a ductile fracture across the joints.