Assessment of using the floating bobbin tool for double sided friction stir welding of aluminium

The friction stir welding is a suitable substitute for gas metal arc welding for joining aluminum alloys in aerospace and shipbuilding industries. Recently a new friction stir welding method named floating bobbin tool friction stir welding has been introduced, that enables the implementation of this process with almost zero vertical force. Another advantage of this technique is the simultaneous double sided welding and the symmetry of the stirred region along the thickness. This paper focuses on the use of double sided friction stir welding technology with a floating bobbin tool for joining pure commercial aluminum. The tool used in this process was made from hot working steel with a hardness of 52 HRC. This tool has two shoulders and a threaded cylindrical pin. After performing the welding process, in order to assess the quality of the connection, non-destructive tests of visual inspection, radiography, as well as destructive tests of tensile, bending, hardness and metallography performed on a welded sample. Non-destructive tests confirmed the perfection of a welded sample with optimal parameters. The results of the tensile test showed that the connection efficiency was very significant and reached about 80%. In addition, the fracture strain of the welded sample was 80% higher than that of the base metal. Accordingly, the development and exploitation of this method provides the potential for the development of a low cost, solid state and reliable technology, and the feasibility of designing inexpensive equipment for mobile friction stir welding.