الفهرس | Only 14 pages are availabe for public view |
Abstract Recently, modem industries particular aerospace, automotive and shipbuilding have addressed a large attention to a new welding technology based on a solid state welding process, called friction stir welding (FSW). This advanced welding technology proved magic solution in welding unweldable and dissimilar materials. The present investigation aims to study the aluminum weldment quality using the friction stir welding technique with a double shoulder tool instead of the common single shoulder one. Attempts have been made to understand effects of process parameters include tool geometry, rotation speed, and welding speed on aluminum weldment. In this direction, a single shoulder tools with five different pin profiles (straight cylindrical, right threaded cylindrical, left threaded cylindrical, tapered cylindrical, and right threaded tapered cylindrical) and a double shoulder tools with three different pin diameters investigated. The operation parameters included three rotation speeds and three welding speeds were also investigated for double shoulder tool and compared with single shoulder one. Also an attempt has been done to correlate welding tool geometry and the operation parameters in the friction stir welded joint with temperature distribution across welded joints. Evaluations of friction stir welded joints were carried out by tensile, impact, and Vickers micro-hardness tests. The tensile behavior expressed as strength and elongation% were investigated and impact energy at room temperature and at range of temperature from ( -70°C to l50°C) were examined. Vickers micro-hardness tests were performed and assessed at single shoulder tool with different tool pin profiles. All results were compared and evaluated with the aluminum base metal It is found that the shape of the tool pin profile is affecting on the amount of heat which generated during friction stir welding and on the mechanical properties of the weldments. The welded joint strength reached about 90, 80 and 76% of base metal at controlling rotation speed, welding speed, tool pin diameter respectively. In addition, elevated temperature impact energy increased with decreasing temperature. Sharp DROP in impact energy recorded at temperature below sub-zero, this was true for all process parameters. On the other hand, Friction stir welding introduced softening in the stir zone and thermo-mechanical affected zone. |