On September 18th, the journal “Journal of Manufacturing Processes” published a paper titled “Standoff-free vaporizing foil actuator welding: Process principle, experimental validation, and mechanisms analysis”. This paper introduces a novel high-velocity impact welding process: the standoff-free vaporizing foil actuator welding (Standoff-free VFAW). This technique employs a new type of driving mechanism, overcoming the geometric placement constraints between the flyer plate and the target plate inherent in traditional impact welding processes. It enables welding without requiring an initial standoff distance between the two plates. The feasibility and general applicability of the proposed process were validated through experiments. The welding performance was evaluated using shear tests, peel tests, and microstructural analysis. The results indicate that the proposed process can successfully weld T2-copper to 304 stainless steel and AA5083-H112 to 304 stainless steel.

Fig. 1 Experimental device and principle: (a) Experimental device; (b) Principle of standoff-free VFAW process; (c) Shape of aluminum foil.

To validate the feasibility of Standoff-free VFAW, a free section length of 100 mm was chosen, with a 2 mm distance maintained between the driver plate and the flyer plate. The welding voltage was initiated at 16 kV and subsequently reduced in 2 kV increments to investigate the critical welding voltage, the flyer plate was T2 copper and AA5083-H112. The experimental results are depicted in Fig. 2. Referring to Fig. 2, in comparison with the conventional VFAW technique, the absence of an initial standoff distance means that the flyer plate did not undergo noticeable deformation in the weld area. These findings confirm the feasibility of the standoff-free VFAW technique.

Fig. 2 Under varying weld voltages (no welding at U=6 kV), the macroscopic appearance and the side view of the standoff-free VFAW samples are presented (side view is illustrated using the case of U=12 kV).

To investigate whether the welding interface of standoff-free VFAW is similar to that of conventional impact welding, a scanning electron microscope (SEM) was employed to conduct a microstructural analysis of the standoff-free VFAW welding interface. The results show, similar to the interface characteristics of conventional impact welding, the weld interface of standoff-free VFAW exhibits waveform interface features, as well as vortexes, microcracks, and voids.

This paper proposes a novel Standoff-free VFAW process and validates its feasibility and general applicability through welding experiments involving copper-steel and aluminum-steel joints. The successful implementation of Standoff-free VFAW demonstrates that an initial Standoff distance is not a prerequisite for impact welding, thus breaking the existing technical constraints of high-velocity impact welding and providing a new perspective for the field. SEM results indicated that the welding interface of Standoff-free VFAW exhibits a typical wavy interface, along with features such as diffusion layers and vortices.

Link: https://doi.org/10.1016/j.jmapro.2024.09.051