Abstract
Friction welding of 6061 aluminum alloy was carried out in order to examine the relationship among deformation heat input at the upset stage, upset burn-off length and joint performance. The joint performance was evaluated by tensile testing and fatigue testing. Stabilized tensile strength was obtained when the deformation heat input at the upset stage and the upset burn-off length exceeded 200J/s and 4mm, respectively. Weld condition at the weld interface and the width of softened area affected fatigue strength more than tensile strength. That is, when the weld condition at the weld interface is good and the softened area is wide, fatigue strength increases because the stress disperses in the softened area. On the other hand, when the weld condition at the weld interface is good and the softened area is narrow, and when the weld condition at the weld interface is somewhat poor in spite of the wide softened area, fatigue strength decreases because the stress concentrates at the weld interface. The fatigue limit obtained by the fatigue testing reveals that, when the deformation heat input at the upset stage and the upset burn-off length exceed a certain value, sound joints can be produced.
