In this paper, in order to clarify the fatigue strength characteristics of dissimilar material friction welded joints of A6061 aluminum alloy to S35C carbon steel, the friction welded joints were produced under the three welding conditions involving a good welding condition and the fatigue strength characteristics of the welded joints was evaluated using a cantilever type rotary bending fatigue testing machine. The tested data were analyzed by Weibull distribution. The results indicated that increasing the upset pressure P2 causes a decrease in the fatigue limit and tends to failure in the softened A6061 base material, moreover, under same stress level, the dispersion of fatigue life distribution of the welded joints is large compared with that of the base material.
Friction welding is a solid phase welding method which effectively utilizes the friction heat as a heat source, and the welding of dissimilar materials is much easy while the welding is difficult in the fusion welding. Therefore, application and fundamental study of the friction welding of dissimilar materials are widely carried out recently. Friction welding has the excellent features in material saving, decrease of production process, high energy efficiency, low cost and easiness of automation. The friction welded joint has mainly been used for steering shafts, propeller shafts, rear axle housing of automotive structure material, various industrial machinery, cutting tool, etc. Recently, the application of aluminum alloys to automobile, aircraft and industrial machinery is positively carried out from the viewpoint of resource conservation and energy saving. Generally, the joint performance of the friction welded joints is evaluated in static strength test such as bending and tension. However, present authors have reported that the joint efficiency of fatigue strength of friction welded joints does not become 100 % for some combination of welded materials and friction welding conditions.
