الفهرس 
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Abstract
Heat treatable aluminium alloys are difficult to weld by traditional welding
techniques. By avoiding solidification, hot cracking and many other defects will not form.
Therefore, Friction Stir Welding (FSW) process is used where the melting temperature is
sidestepped. This relatively newly invented process has created outstanding attention. The
main intention of this research is to join AA 2024-T4 with the existence of the cladding
layer, and AA 7075-T6 using FSW in a T-joint configuration.
Mechanical properties investigation has done while taken into consideration the
structural change of the welded zones. The effect of tool dimensions, tool traveling speed,
and rotational speed in the welded joints were discussed. Three different tools were used
with different shoulder to pin ratio 3.36, 3.28, and 4.31. After optimization, the best tool
dimension has used with the different rotational and welding speeds. Three conditions at
800 rpm with 50,75, and 100 mm/min traverse speed, and two other conditions at 1000 rpm
with 50 and 100 mm/min were used. After FSW, macrostructure and microstructure
analyses were done using optical microscopy. The results showed a sound T-welds with no
obvious defects at high rotational speed, 1000 rpm. To have an insight into the mechanical
properties, hardness measurements and tensile testing were carried out. Furthermore,
fracture surface of the tensile specimens was investigated.