Ultrasonic Spot Welding of Nickel Foam Sheet and Aluminum Solid Sheet

Abstract

Nickel foam sheet composed of three-dimensional (3D) triangular struts and aluminum solid sheet are welded via ultrasonic spot welding. The foam underwent acceptable thickness reduction and deformation, whereas most of the porous structures remain intact. Energy dispersive spectroscopy (EDS) analysis shows that little interdiffusion is noticed across the welding interface, leading to the formation of only a small amount of solid solution, and intermetallic compounds. Infrared temperature measurements show that the joint-temperature variation of the welding interface is substantially lower than the solid-solution temperature of Al/Ni, and the welding process is in solid state. The resistance of the joints is measured, and the contact resistance is calculated. The specimen with excellent interface connection exhibits low contact resistance. As the welding energy increases, the failure mode transitions from interfacial fracture to pull-out fracture, with the tensile load and fracture energy reaching 58 and 69%, respectively, of those corresponding to the nickel foam base metal. Fracture occurs exclusively on the nickel foam sheet, and the fracture mode is ductile fracture.

Microstructural Evolutions under Ultrasonic Treatment in 304 and 316 Austenitic Stainless Steels: Impact of Stacking Fault Energy

“…One of these effects, called "acoustoplastic," is a temporary softening due to the imposing ultrasound during the plastic deformation of metallic materials. [1] Considering this effect, ultrasound is suitable for use in several manufacturing processes such as welding, [2,3] additive manufacturing, [4,5] surface impact treatment, [6,7] and metal forming. [8,9] The stress reduction caused by acoustoplastic can be divided into stress superposition, dynamic impact, and acoustic softening.…”

A review of quality monitoring for ultrasonic metal welding

“…Scanning electron microscopy (SEM) was used to observe the morphology of ultrasonic weld joint and fracture, and component analysis was carried out in combination with the cross-section of EDS interface of joint. Xie et al 76 used ultrasonic welding to join aluminium solid sheet with nickel foam and observed the weld joints. As shown in Figure 13, the SEM photograph can clearly show the joint interface of aluminium and nickel foam, and the mechanical lock occurs at some area of the welding interface.…”

“…SEM images of the Al/Ni foam weld interface at different welding energies and EDS line scan results (yellow arrows show the scanning direction): (a) 10 J, (b) 30 J, (c) 50 J and (d) 70 J. 76 …”

“…Xie et al 76 performed resistivity measurements of ultrasonic welded joints. The results show that the resistance at the joint is higher than that of the unwelded material.…”