MIG-laser combined welding of aluminum alloy to 304 stainless steel

In this paper a study on some aspects of the weldability of a copper aluminum alloy to an austenitic stainless steel through a MIG-Laser combined heat source is presented. In particular the effect of the heat source position over the welding sheets on the interface between the two metals was investigated. Using a steel feed wire the combined heat source was positioned in several working positions. Firstly, the axis connecting the torch to the laser beam was set parallel to the seam in the laser leading layout. Alternatively, the axis was rotated respect to the seam so the filler material dropped on the steel or the aluminum side. In the latter case an aluminum alloy feed wire was used. The different layouts had some goals to reach. In the first position it was aimed to maximize the welding penetration and evaluate the brittle intermetallic phases that form in different material joint. The second position aimed to limit the stirring effect of the two alloys and in turn the formation of the brittle phases by fusion of only was side of the joint. The morphology and microstructure of the weld through electrical and optical microscopy were characterized and here presented. The mechanical property of the weld was assessed by means of the tensile test.