الفهرس 
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Abstract
The aim of this thesis is improving of quality and efficiency of welding
process. The friction stir welding (FSW) was chosen to be applied on
AA6063 Aluminum alloy. The final results should demonstrate that the
welding joints properties satisfy design requirements, determination of the
best mechanical properties of the welding joints and develop a
mathematical model to be more reliable as the main aim of this thesis.
In this study, the welding parameters of FSW are traverse speed (B), tool
rotational speed (A) and tool pin profile (Ḉ). The tool rotational speed
values are (20, 40 & 60) mm/min. The welding tool rotational speed
values are (800, 450 & 230) rpm. The last parameter to be considered is
welding tool pin profile(Ḉ) with three different shapes of threaded taper
profile, tapered profile & cylindrical profile. The target of this study is to
find influence of these parameters on the FSW process, the mechanical
properties (tensile strength, hardness & bending strength), and macromicrostructure (to discover the welding defects). Moreover, the genetic
algorithm (GA) process conducted within the ranges of the welding
parameters to optimize and increase the utility of welding process
economics and for more quality of welding joints by maximizing the
hardness, tensile strength and bending strength. The welding tool rational
speed within (230 rpm A 800 rpm), welding traverse speed within (20
mm/min B 60 mm/min), and tool pin profile (Tapered, Cylindrical and
Threaded Taper). Then, the finite element model was stablished to study
structural analysis, heat transfer on the numerical designed model by using
finite element method (FEM). The maximum contribution percentage for the welding pin profile equal to 39.13% for hardness model and the
welding pin profile equal to 32.96% for tensile strength model. The
maximum contribution percentage for traverse speed = 76.04% for
bending strength model. The GA results giving the maximum hardness at
A = 230 rpm and B = 20 mm/min as a following (threaded tapered profile
= 32.66 HRB, cylindrical profile = 29.02 HRB and tapered profile = 27.46
HRB). The GA results was given the maximum tensile strength of 77.36
MPa at (A = 230 rpm, B = 20 mm/min and threaded tapered profile). The
GA results giving the maximum bending strength at A = 563.8 rpm and B
= 60 mm/min as a following (threaded tapered profile = 155.91 MPa,
tapered profile = 155.31 MPa and cylindrical profile =140.95 MPa). The
results of macro and microstructure study are helping to distribute the
defects according to defect size discovered. Then, the analysis was shown
that 63% of the defects are controlled by 50% of the root causes. The
defects within (0.2 – 0.4) mm are caused by increasing in welding tool
rotational speed with traverse speed and insufficient stirring surface. The
defects within (> 1 mm) are caused due to low friction heat generation,
excessive tool vibration and wrong setting of the joints. The defects within
(0.8 – 1) mm are caused by pin profile type, pin depth and increasing in
turbulence of the plasticized metal. The finite elements model identifies
the temperature distribution along (X & Y) coordinates. The results
providing that the temperature distribution depending on the welding tool
pin profile. Whereas, the threaded taper profile giving regular temperature
distribution. The reliability analysis results giving the reliability at high
criticality (R) of 80%. The considered planned duration (Ṫ) is equal to 42
sec for the welding joints and 350s for the welding tool as an average
value.