Aluminum is becoming increasingly important in automotive vehicle construction. On the one hand, its use leads to a reduction in vehicle weight, and on the other hand it offers advantages over fiber composites in terms of recycling, i.e. reusability. Die-casting alloys are used when complex components are required at low costs. Furthermore, the use of high-strength wrought aluminum alloys (6XXX and 7XXX) is increasing in crash-relevant structures, for example the battery tray. However, during laser welding of these material combinations, there is a high risk of pore formation (die casting alloys) and hot cracks initiation (high-strength wrought alloys).
At Fraunhofer IWS, a novel process technological approach is under development, using laser beam welding with dynamic beam shaping. This welding technology significantly controls the formation of the melt pool and the stress situation during solidification and cooling of the melt. Through the defined selection of process parameters, on the one hand the porosity of the die-cast welds can be significantly reduced. On the other hand, hot cracking of critical materials can be reliably avoided even without the use of filler metal.
The object of this presentation is to demonstrate the potential of laser welding with high-frequency beam oscillation for aluminum battery tray manufacturing. Set-up and parameter field of the welding process are presented and results of the process development for typical joint geometries in combination of cast and wrought aluminum are discussed. Initial results from the preliminary tests for final component manufacturing are presented too.