Fig. 1 shows an arrangement of an upper and a lower welding tip, welding specimens and clamping vices for ultrasonic butt welding of specimens end to end. The ultrasonic butt welding system consists of a 15 kHz powerful ultrasonic vibration source, an upper passive vibration system and a welding frame with hydraulic static pressure sources to clamp the welding specimens. The vibration source was driven by a 50 kW static induction thyristor power amplifier [1–4]. The driving side specimen is clamped by a metal vice for avoiding the fatigue failures by transverse vibration of the specimen at a transverse nodal position where was carefully chosen for the material and dimensions of the welding specimens. The clamping position is shown in Fig. 1.
The welded surfaces were driven to vibrate parallel to each other by welding tips and were welded together end to end. The welding specimens used were 6-mm-thick and 10–20-mm-wide aluminum (JISA1100P, JI-SA5052P) and stainless steel (SUS304P) plates. The welding surfaces were finished to be flat by a milling machine. The specimens were degreased and cleaned by chlorothene and given no further treatment.