Process Stability during Laser Beam Welding with Beam Oscillation and Wire Feed

Abstract

Beam oscillation in laser material processing makes it possible to influence process behavior in terms of energy distribution, stability, melt pool dynamics and solidification. Within the setup presented here, the beam is oscillated transverse to the welding direction, and the filler wire is fed to the melt pool of a butt joint with an air gap. One advantage of this setup is the large gap bridging ability. Certain parameter sets lead to the so-called buttonhole welding method, which allows laser welding of smooth and nearly ripple-free seams. Observations showed a transition area between conventional keyhole and buttonhole welding in which the process is destabilized. Welds made with parameter sets from this area contain critical seam defects. Welding experiments with high-speed video recording and a simplified analytical model about the wire-beam interaction have helped to elucidate the mechanisms behind this. EN AW-6082 sheet material in 1.5 mm thickness and ML 4043 filler wire with 1.2 mm diameter were used. The investigations lead to the conclusion that partially melted wire segments result at certain parameter relations which hinder the formation of a buttonhole. If these segments are prevented, buttonhole welding occurs. In the transition area, these segments are very small and can lead to the detachment of a buttonhole, resulting in the named seam defects.

Morphology, mechanical property, and molten pool dynamics in spot modulated-PLBW of Ti6Al4V alloy sheets with air gap condition

“…Alderlink [11] carried out a laser welding experiment on a 1.1 mm thick AA5182 plate and found that the gap size accounting for ∼ 50% of the plate thickness can be welded by wire feeding, as opposed to 33.3% without feeding treatment. Schultz [12] successfully conducted the laser tailor-welding process of a 1.5 mm thick AW-6082 plate with a reserved air gap of 1.0 mm, where the filler wire was fed coaxially and was meanwhile swung horizontally (vertical to the traveling direction) to compensate for the uneven deposition of metal drop. Furthermore, Huang et al [13] undertook laser-MIG arc hybrid welding and suggested that the gap-bridging ability could be highly improved with larger laser-wire distance and higher wire feed speed either while maintaining the process stability.…”

The role of filler wire and scanning strategy in laser welding of difficult-to-weld aluminum alloys

“…In addition, increasing the oscillation width and frequency can result in more signi cant mitigation of weld porosity and consequently higher joint strength [19]. Schultz [20] proposed the oscillation as a mean for evenly distributing the energy on the tip of the ller wire. Some researchers have focused on the effect of ller wire and laser oscillating on the weld formation, grain growth, molten pool behavior and defect suppression and both methods can effectively improve the weld quality in terms of: (a) deal with gaps, misalignments, differences in thickness, (b) reduce pore formation and (c) reduce crack susceptibility.…”

Laser welding with and without filler wire of aluminum sheets produced by rolling and additive manufacturing for e-mobility applications

“…Yu et al [6] investigated the importance of wire-laser beam mutual position and distance for promoting a stable melt pool and a smooth wire melting. Schultz et al [7] proposed the oscillation of a high brilliance laser beam as a mean for evenly distributing the energy on the tip of the filler wire instead of defocusing or using a low brilliance beam with a large spot. They also demonstrated that this technique can also have beneficial effects in gap bridging.…”