Methods to influence the meltpool dynamics and the element distribution in laser welding of aluminium alloys with filler wire

Abstract

With increasing utilisation of high strength aluminium alloys, high material thickness and complex joint geometries the use of filler wire is recommended in many cases, especially in order to avoid hot cracking. Regarding increasing material thickness, the homogenous distribution of the alloying additions (in particular Si) throughout the whole melt pool is becoming more and more important. Hot cracking in the bottom line of a laser weld – even when filler wire was added – is still a typical problem.This contribution presents results on taking influence on the weld pool dynamics by the utilisation of electromagnetic volume forces. Here, they are produced by an external current, which is applied via the filler wire. A significant homogenisation of the silicon distribution throughout the molten area can be achieved in this way. Furthermore, the influence of process gas on the meltpool dynamics and the element distribution will be discussed.With increasing utilisation of high strength aluminium alloys, high material thickness and complex joint geometries the use of filler wire is recommended in many cases, especially in order to avoid hot cracking. Regarding increasing material thickness, the homogenous distribution of the alloying additions (in particular Si) throughout the whole melt pool is becoming more and more important. Hot cracking in the bottom line of a laser weld – even when filler wire was added – is still a typical problem.This contribution presents results on taking influence on the weld pool dynamics by the utilisation of electromagnetic volume forces. Here, they are produced by an external current, which is applied via the filler wire. A significant homogenisation of the silicon distribution throughout the molten area can be achieved in this way. Furthermore, the influence of process gas on the meltpool dynamics and the element distribution will be discussed.