Friction stir welding of aluminium casting alloys

The results of testing friction stir welding quality in relation to EN AC-43200 (AK9) and EN AC-45000 (AK64) aluminium casting alloys are presented. The test joints were made with the use of a welding machine constructed on the basis of numerically controlled milling machines. The assessment of the joint quality was made based on visual inspection, mechanical testing, weldment structure analysis and hardness tests. The purpose of the investigation was to discover the possibility of friction stir welding of casting alloys and the influence of welding conditions on joint properties and structure. The test results show good weldability of aluminium casting alloys by the FSW method. Sound welds can be obtained in a relatively wide range of welding parameters while the weld strength is satisfactory. In order to obtain the highest quality joints, the workpieces must be pressed onto the other, while the welding process cannot run with excessively high speed. The best mechanical properties of the joints were achieved when the friction process was conducted at a rotational speed of the mixing tool of 900 rpm.