الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Welding of thick sections aluminum alloys by friction stir welding technology (FSW) needs to overcome many challenges because of its necessity for industrial applications such as, ship building, rail cars, military vehicle. In this study, 40 mm thickness of 5083-O aluminum alloy plates were bead on plate FSWed. The welding was performed at different relatively low rotation speeds of 100, 125, and 150 rpm and different travel speeds of 100, 125, and 150 mm/min, while keeping the other FSW parameters are constant. Our objective was to optimize the parameter window and examine how the change in welding parameters influences the microstructures and mechanical properties of the produced welds.
Macro and microstructures investigation were carried out to examine the weld efficiency using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with EDS and EBSD techniques. Mechanical properties in terms of hardness measurements and tensile properties of the stir zone along the thickness direction from the top to the bottom were investigated. The results showed that the designed threaded and tapered W302 tool succeeded to weld 40 mm
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thick section AA 5083 with a plugging depth of 30 mm without failure. Defect-free welds are produced with microstructure exhibited a gradient distribution along the thickness direction. Equiaxed fine recrystallized grains observed in the stir zone SZ compared to elongated coarse grains in the base material. The ultimate tensile strength values along the thickness of the SZ from top to bottom are closed to each other and the maximum ultimate tensile strength of 285 MPa is obtained for the welding condition of 150 mm/min and 150 rpm. While, slight variations in ductility and hardness are detected for USZ, MSZ and LSZ for all the welding conditions.