Product Code: ICAL09_107

On the Meaning of Zinc Coatings in Hybrid Welding of Aluminium to Steel
Authors:
Frank Vollertsen, BIAS GmbH; Bremen Germany
Claus Thomy, BIAS GmbH; Bremen Germany
Presented at ICALEO 2009

Laser MIG hybrid welding was recently suggested as a feasible process for joining of aluminium to steel for both structural and tailored blank applications. In this process, the aluminium is molten to create a brazed bond to the zinc-coated steel sheet, which remains solid. To further investigate the effect of process parameters, laser power, MIG arc power, wire feed rate, welding speed and arc position relative to the abutting edges were varied for the case of butt joints of aluminium alloy AA 6016 to DC05 zinc-coated mild steel (sheet thickness approx. 1 mm). By metallographic cross sections and tensile tests, the effect of these process parameters on joint properties such as wetting length, intermetallic phase layer thickness and tensile strength was elucidated. Based on these results, a parameter envelope resulting in adequate and reproducible joint properties was established. On this experimental basis, a model to predict wetting length in dependence of processing conditions was suggested, with both model and experiment showing a correlation of wetting length to the melting isotherm of the zinc coating. These results shall contribute to an improved understanding of the process and promote an increased use of this process for producing dissimilar joints.