Effect of Filler Wires on Cracking along Edges of Magnesium Welds

Since Mg alloys often have a relatively low eutectic temperature T-E, they are susceptible to intergranular liquid formation and hence cracking in the region of the workpiece along the weld edge, where temperature exceeds T-E during welding. To evaluate the effect of the tiller wires on weld-edge cracking in butt welding of AZ91 Mg alloy, the circular-patch weld test was used. An AZ91 Mg circular patch was fitted inside a circular hole in an AZ91 Mg workpiece and butt welded to it. Mg filler wires AZ31 Mg and AZ92 Mg were used for welding. Temperature (T) was plotted against fraction solid (f(s)) for the workpiece and the weld. It was found that the susceptibility to cracking can he determined by comparing these two T-f(s) curves.