Laser Beam Welding of AZ31 Magnesium Alloy with Filler Strip

The 2-mm AZ31 magnesium alloy sheets were laser beam welded using filler metal in the shape of strip. Two kinds of the filler strips, i.e., AZ31 and AZ31 +1.5wt% Mn were adopted. The effects of the filler strip on the microstructures and tensile properties of the welded joints were investigated. As compared with the autogenous welding process, the welding process with filler strip brought about a decrease in the fusion zone (FZ) area and a reduction in grain growth in the heat-affected zone (HAZ). A significant grain refinement in the FZ was achieved by the addition of the filler metal containing Mn, and the equiaxed grains with the average size of about 6.0 mu m were obtained. The joints welded with filler metal exhibited improved tensile properties compared to those welded autogenously, and the highest joint efficiency was obtained with the addition of the AZ31 +1.5wt% Mn filler strip, which was up to 99%.