Nd:YAG laser welding of fine sheet metal butt joints in AZ31 magnesium alloy

Magnesium alloys have been used increasingly in various areas of industry, such as the automotive sector, electronic components. A reliable method for joining components produced with these materials will definitely allow for a wider use of these alloys. In this article, the laser welding process with an Nd:YAG laser using a maximum power of 2 kW was studied and reported. The effect of welding parameters, such as laser and welding, was analysed. Metal sheets of 1mm thickness in AZ31B magnesium alloy were butt-welded with helium and argon as shielding gas in the absence of filler material. The mechanical characteristics were measured during tensile tests, using digital image correlation (DIC) as a deformation measurement technique. After a preliminary experimental plan aimed at exploring the range of process parameters, the welding process was optimized using an approach based on the design of experiments (DoE). Consecutive experimental plans led to optimized butt joints, which, following a tensile test, showed a sound weld bead with fracturing in the base material. Local strain analysis by DIC highlighted different tensile behaviours, in terms of deformation of the weld bead, in the optimized butt joints with respect to those that were not optimized