Improvement of laser welding of Zn-coated steel and aluminum alloys thin sheets using shaped laser intensity distribution Available to Purchase

This article presents a study of the improvement of laser welding of metal thin sheets used in the automotive industry using an adapted power distribution at the focal point. The concerned materials are galvanized steel and aluminum alloy sheets, which are welded in a lap joint configuration using a continuous wave Nd:YAG laser. The difficulties of this kind of materials are due to instabilities of the welding process characterized by pores and ejections generation. First of all, we determined and quantified the influence of parameters such as depth of penetration, depth of focalization, welding speed, keyhole elongation, keyhole opening, distribution of laser power and thickness of the sheets on process stability and bead quality. The good obtained results are explained with the help of an observation campaign which permitted a better understanding of the physical phenomena. It was also found out that the sheets surface cleanliness has an unexpected influence on the process stability.