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Friction welding of C6191 aluminum bronze to SUS304L stainless steel was carried out to examine its weldability. Joint strength was evaluated by fatigue strength. The C6191 and the SUS304L at the weld interface were hardened, while the heat affected zone of the SUS304L was slightly softened. A reaction layer of 1–5 μm that consisted of component elements of the base metals was observed at the weld interface. The fatigue limit of the joint welded under the optimum welding condition was higher than those of the base metals because of the hardening of C6191 and SUS304L, and the fatigue limit of joints decreased as the friction time or the upset pressure varied. In particular, the fatigue strength of joints welded under the conditions varied the upset pressure which was lower than that of the C6191 base metal.

Stud joints of 5083 aluminum alloy were welded by arc stud welding and friction welding, and their joint strengths were examined. In the weld zone of the arc stud welded joint, no change occurred in the hardness distribution. In contrast, the weld zone of the friction-welded stud joint softened slightly on the plate side and hardened on the bar side. The tensile strengths of the arc stud welded joints with weld reinforcement and without weld reinforcement, and the friction-welded stud joints without burrs were 233, 231 and 180 MPa, respectively, and all joints fractured at the weld zone. In the bending test, all joints fractured near the weld zone at a bending angle of approximately 20°. In the fatigue test, the fatigue strengths of the arc stud welded joints were higher than those of the friction-welded stud joints, and the fatigue limits of the arc stud welded joints with weld reinforcement and without weld reinforcement, and the friction-welded stud joints without burrs were 43, 40 and 13 MPa, respectively.

Friction welding of SUS304 stainless steel to C1100 tough pitch copper was carried out and tensile strength of joints was examined. Also, a statistical analysis of the tensile strength data was investigated for judging a suitability of friction welding conditions on this joint. It was found that the SUS304 and the C1100 near the weld interface hardened and softened, respectively. There were fine-grained structures composed of much copper and a little of iron, chromium and nickel near the axial center at the weld interface. Tensile strength tended to increase with a friction time and with an upset pressure, and the maximum joint efficiency for the C1100 base metal was 101%. The shape parameter in Weibull distribution increased with an increase in mean value of tensile strength and with a decrease in dispersion of tensile strength. It seemed that the shape parameter is useful for judging the suitability of friction welding conditions.

t. Friction welding of FC250 common grade cast iron was carried out to examine the weldability and temperature distribution near the weld interface during welding. The joint strength of both solid and pipe joints was evaluated by tensile tests. The highest tensile strengths in the solid joints and pipe joints were 317 MPa (79% joint efficiency) and 381 MPa (95% joint efficiency), respectively. A fine-grained interfacial layer of FC250 formed near the axial center at the weld interface in the solid joints, whereas there was no fine-grained interfacial layer in the pipe joints. The welding material temperature at the axial center was higher than that at the periphery in the solid joint. There was little difference in the temperature distribution between the solid joints and pipe joints.