The Background to the Weldable Al‐Zn‐Mg Alloys Available to Purchase

THE alloys under consideration contain only zinc and magnesium as the major alloying additions. The total alloy content varies between 5 and 7 per cent whereas the high strength aircraft alloys have a total content of 8 to 10 per cent and may also contain up to 2 per cent of copper. A wide range of mechanical properties can be obtained with the weldable alloys and some of these properties closely approach those of the aircraft alloys. Problems associated with weld metal cracking and heat affected zone recovery arc normally severe with age hardening aluminium alloys but are greatly attenuated with the weldable alloys.