Evaluation of tensile strength and fatigue strength of 6061 aluminum alloy friction welded joint

摘要

Friction welding of 6061 aluminum alloy was carried out in order to examine the relationship between deformation heat input during upset stage, upset bum-off length and joint performance. The joint performance was evaluated by tensile test and fatigue test. Stabilized tensile strength was obtained, when deformation heat input during upset stage and upset burn-off length were over about 200J/s and over about 4mm, respectively. The welding condition at the weld interface and the width of softened area effected on fatigue strength more so than tensile strength. That is, in the joint of which the welding at the weld interface is good and the softened area is wide, fatigue strength become high because the stress is dispersed in the softened area. On the other hand, in the joint of which the welding at the weld interface is good and the softened area is narrow and in the joint of which the welding at the weld interface is poor in spite of having the wide softened area, fatigue strength become low because the stress concentrates at the weld interface. Judging from the fatigue limit obtained from the fatigue test, in over value in which there are deformation heat input during upset stage and upset burn-off length, the sound joint can be produced.