Metal-inert gas welding of magnesium alloys

Since magnesium alloys have a melting point of 600°C and a vaporisation point of only 1 100°C, difficulties (particularly spat. tering) frequently arise during fusion welding. The regulation of the energy supply into the filler metal must guarantee that the wire melts completely but must not lead to vaporisation. Therefore, welding tests were performed with special power-source characteristics. In this case, a short arc with pulse superimposition or a triggered short arc was used together with a filler metal with the same composition as the parent metal. 1.35 to 5.0 mm thick extruded sections and rolled sheets made of both AZ31 (MgAl3Zn1) and AZ61 (MgAl6Zn1) served as parent metals. The tensile strengths of the welded joints were 80 to 100% of those of the parent metal and the bending angles were up to 60°. The fatigue strength reached approx. 50% of the values of the parent metal and, when the weld reinforcement had been machined off, as much as 75%.