Structure and mechanical properties of MIG welded butt-joints of magnesium alloys

Abstract

This article presents an assessment of the structure and the mechanical properties of butt joints of as-cast magnesium alloys AZ91, AM-Lite and AM50 welded with the MIG welding method. The shielding gas used was a mixture of argon and helium. The macro- and microstructures were evaluated by means of a light microscope and a scanning electron microscope using metallographic specimens cut along a plane perpendicular to the welding direction. An analysis of the distribution of alloying elements has been performed with the use of the scanning electron microscope. The mechanical properties of joints have been evaluated on the basis of microhardness distribution in the joints and tests of the bending and tensile strength of weld joints. The results of this assessment show that it is possible to achieve high quality butt joints of magnesium alloys with the use of the MIG welding method. Trace amounts of porosity have also been observed in the joint area.