Fig. 2 shows (1) upper view, (2) side views and (3) cross-sections of the welded (a) aluminum–stainless and (b) stainless steel–stainless steel specimens. The welded surface of aluminum–stainless steel is linear, and thin
burrs are produced only at the side of the aluminum specimens because the hardness of aluminum is less than that of stainless steel. The welded surface are difficult to observe in the cross-section of the completely joined stainless steel specimens but some cracks are found in defectively joined specimens.
Fig. 3 shows broken conditions of welded aluminum alloy-stainless steel and stainless steel specimens after tensile test.
The relationship between welding tip vibration am-plitude and weld strength of 6-mm-thick and 20-mm-wide aluminum and stainless steel specimens is shown in Fig. 4. The welding tip vibration amplitude is altered from 17 to 27 lm (peak-to-zero value). The static clamping pressure at the welding surface is 20 MPa and the welding time is maintained at 2.0 s. The weld strengths obtained are near to the aluminum specimen’s strength over all vibration amplitude range. Electric input power was approximately 4 kW.