Development of a bonding interface between steel/steel and steel/Ni by ultrasonic welding

Abstract

Ultrasonic welding is a solid-state welding technique that can bond materials at a relatively low temperature and pressure. In this study, steel/steel and steel/Ni combinations were successfully bonded by ultrasonic welding, and the development of the bonding interface was examined. The bonding strength was obtained by a lap shear test and increased with welding time, as did the fraction of bonded area observed by SEM. The bonding process sequence was investigated by SEM and electron backscatter diffraction (EBSD) analysis of a cross-section at the bonding interface. It was revealed that abrasion is caused by oscillation to form small particles consisting of steel and Ni and that the particles are grown and subsequently flattened with welding time. Bonding is achieved by the flattened particles spreading along the bonding interface without any voids.

Effect of surface roughness on bonding interface formation of steel and Ni by ultrasonic welding

“…As shown, contact areas with island shapes are distributed at the fractured surface and expanded along the oscillation direction, and their numbers increased with welding time. The fracture observations in S/S with increasing welding time also can be referred to our previous study [12], whereas the contact areas were examined by energy dispersive X-ray spectrometry; they exhibited Ni composition on the steel side and Fe composition on the Ni side, and vice versa.

Figure 3 Fractured surfaces of IF steel in the case of rough/smooth after (a) 0.01 s; (b) 0.25 s; (c) 2.0 s; and (d) 2.5 s.

…”

“…At the fractured surfaces of R/S after 0.01 s of welding (Figure 3(a)), the contact areas in S/S [12] were smaller and more uniformly distributed than those in R/S. Further, the intervals of contact areas perpendicular to the oscillation direction in R/S were larger than those in S/S.…”

“…A high-frequency oscillation of 20 kHz with After USW, to evaluate the bonding strength, lap shear tests using a tensile test machine (AGS-50kNG, Shimadzu) was conducted for each welded specimen. Schematic setup for USW and the lap shear test can be referred to our previous study [12]. In the present study, the bonding strengths for each condition were averaged from five tests.…”

“…Al) [10, 11]. In bonding steels and other dissimilar metals by USW, it has been reported that an intermixed bonding interface between steel/steel and steel/Ni can be obtained by flattening wear particles with plastic deformation, and that the bonding strength of joints evolves with an increase in the bonded section [12].…”

Microstructure and Mechanical Properties of an Ultrasonic Spot-Welded Aluminum-to-Aluminum Joint: Response to Interlayer Thickness

“…Chen et al [8] confirmed that USW is a solid phase joining technique and that under the combination effects of high shear frequency vibration and clamping force, two metal sheets can be joined by such a technique. Daniels [9] noted that USW was first introduced for thin foils joining, wire bonding, and tube sealing in the 1950 s. It was used to join thicker metal sheets (such as Al, Cu, NiTi, Fe, and Ni) due to advancements in the welding system technique [10,11,12,13]. In comparison with friction stir spot welding and resistance spot welding, USW has low energy consumption (~0.6–1.5 kJ per weld), because the major heat generation is at the weld interface, not on the top surface of the specimen [14].…”