| Abstract: |
Aluminium and aluminium alloys are common structural materials due to their attractive combination of properties including low density, high strength, good corrosion resistance and proven weldability. Fusion and solid state welding processes are widely used for joining of aluminium and aluminium alloys. For general engineering applications, the three important methods for fusion welding of aluminium alloys are TIG, MIG and Plasma Arc (PAW) welding processes. As the joining of aluminium and its alloy using fusion welding techniques, there are some mechanical and metallurgical problems such as decreases in mechanical properties and metallurgical precipitations on both HAZ (Heat Affected Zone) and the weld metal (WM) of the weld zone to be considered. Consequently, the most significant solid state process for the welding of aluminium alloys to be developed is the friction stir welding (FSW) process that was invented at the Welding Institute (TWI) in 1991 and is capable to welding longitudinal seams in plates. The new technique applies using rotating shoulder tools with screwed pin enables long lengths of weld to be made without any melting taking place. This provides some important advantages compared with fusion welding processes. Despite beiing such a new prossess, FSW has been introduced to many applications with great success and is being actively investigated and used for applications in the aircraft, space vehicel, shipbuilding, railway, combat vehicle and automotive industries.
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