Investigation on a Novel Laser Impact Spot Welding

Abstract

Abstract:In this paper a novel laser impact spot welding (LISW) method is described, in which a hump was formed on the flyer plate on the intended welding spot location by local pre-forming. When the flyer and base plates were placed together to perform welding, the two plates kept in contact over their entire surfaces except at the hump, where a local air gap was enough to guarantee the impact velocity and collision angle to achieve spot welding using laser pulse energy. The presented approach was implemented to join thin titanium foils to copper foils under low laser energy system. Joints with regular shapes were obtained. The microstructure in the weld interface was studied with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It was found that the jetting occurred at the central region of the weld spots due to oblique impact. Wave features were observed in the weld interfaces. The impact energy was found to have significant influence on the wave's characteristics. Moreover, SEM images and EDS analysis did not show apparent element diffusion across the weld interface. Besides, the lap shearing test was used to characterize the mechanical properties of the spot welded joints.

High-Velocity Impact Welding Process: A Review

“…With the confinement layer, the expansion of the plasma pushes the flyer to collide on the target. Materials such as copper, aluminum, steel, and titanium were welded with the LIW method [18,56,57]. The current experimental setup is similar to that for EXW, as shown in Figure 2.…”

Simulation and Experimental Comparison of Laser Impact Welding with a Plasma Pressure Model

“…No crystallization occurred due to LIW and the metallic glass retained an amorphous microstructure after bonding (tested and confirmed only for 1.5 mm laser spot diameter and 47.25 J/cm 2 laser fluence). Liu et al [35] proposed a preforming technique in LIW of 0.03 mm thick titanium flyers to 0.1 mm thick copper targets. In this method, a preformed local hump replaced the gap between the foils normally used in LIW.…”

Laser Shock Processing on Metal

“…Novel potential applications have recently emerged either for laser peening [6], or more broadly, for laser-induced shock waves [7]. Besides, new LSP loading conditions like those using ultra-short pulses in the picosecond [2] or femtosecond range have appeared.…”

“…The original work by Liu et al [7] demonstrates the feasibility of Ti-Cu joining by laser induced spot welding, through the dynamic collision between a thin laser-accelerated titanium flyer plate and a copper substrate, separated by an optimized stand-off distance. An interesting point to notice is the need of jetting formation behind the flyer plate to provide a cleaned impact surface by removing contaminants and ensuring optimum contact between Ti and Cu.…”

“…The following fields are covered in the seven selected papers: materials' behavior and phase transformations under high strain rate (Amadou et al [1]), new loading conditions with ultra-short pulses (Petronic et al [2]) surface modifications induced by laser peening including recrystallization effects (Zhou et al [3]) and warm laser peening (Huang et al [4], Chen et al [5]), and novel applications of LSP such as water droplet erosion resistance (Gujba et al [6]) or impact spot welding (Liu et al [7]). The wide variety of topics related to LSP highlights the extraordinary dynamism and enthusiasm of the growing international LSP community.…”