Friction stir welding (FSW) is a very useful technology for welding of aluminium alloys. This method does not heat the material to its melting point in order to create the weld. In this thesis, the usefulness of FSW for the welding of lap joints was investigated. When welding butt joints, the surfaces must be machined for their fitting, but with the welding of lap joints, that is not necessary.
In this research we investigated the influence of weld depth on properties of friction stir welded lap joints. We used 6 different welding tools with tool pin lengths from 3.1 mm to 5.7 mm and shoulder diameters of 10 mm and 12 mm. Welding parameters were set in order to obtain visually good weld joints. We created multiple samples on which we performed tensile testing. We measured ultimate tensile forces, tensile forces at fracture and the strains, at which these forces were measured. The results of tensile testing were processed and studied. We found out that the tensile strength of a lap joint increases with increasing depth of lap weld. The length of tool pin has a bigger impact on tensile strength of the weld than the linear energy input.
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