الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 176 |  |  |
| | | from | 176 | | |
Abstract
Friction stir welding (FSW) was developed initially for welding some of the aluminum alloys which were difficult to weld using conventional welding techniques. After the remarkable success of FSW in welding these alloys and other sorts of metals. Subsequently, this technique has been applied without any modification for welding polymeric materials. As a result, conventional FSW did not achieve satisfactory joint strength due to the huge differences between the properties of metals and thermoplastic materials. As a consequence, several modifications, developments and patents have been introduced to harmonize this technique with thermoplastic materials. In this study, a FSW machine was designed and manufactured to perform the welding with an easy control interface. The machine was also equipped with an induction heating system to heat the FSW tool during welding. The experimental investigation has been carried out to find the influence of four levels of each of these parameters including pin temperature, rotational speed and welding speed on the mechanical behaviour and macrostructure of polycarbonate (PC) sheets using Taguchi L16 orthogonal array. The results showed the applicability of using FSW at a high welding speed (90 mm/min) produced a joint efficiency of about 80.8% relative to the flexural strength of the parent material. The investigation of samples macrostructure showed that several defects such as macro-cracks, tunnels, flash formation, surface grooves, and root defects are formed as a response to the different interactions between the welding parameters. However, a defect-free weld can be obtained at the proper welding conditions which were found to be at a rotational speed of 1800 rpm, welding speed of 30 mm/min and tool temperature of 50 ◦C. In this situation, the flexural strength of the welded plate jumped to about 92.2% compared with the base material.