Microstructural studies on Al-Zn-Mg alloy welds

Weldments of heat-treatable medium-strength Al-Zn-Mg alloys using three different filler materials (W-Mg, W-MgMn, W-MgZn) were studied. Emphasis is directed towards determining the microstructures of these weldments. In general, it was found that all W-Mg weldments contain relatively fine precipitates and also particles such as Al12Mg2Cr which may be responsible for mechanical properties. In contrast, W-MgZn weldments showed relatively coarse grains which could be responsible for their inferior mechanical properties. Although Zn is added with the intention of improving corrosion resistance, the study have shown that the mechanical properties of this weldment are comparatively inferior to other weldments studied.