Effects of filler metals on the properties of 7175 aluminium alloy electron beam welds

Summary

In electron beam welding of 7175 aluminium alloy plates of 15 mm thickness, the effects of filler (insert) metals on the properties of welds have been investigated by microscopic observation, electron probe microanaly‐sis, and hardness, tensile and impact tests. Hardness of welds without the insert is almost recovered by T76 post heat treatment. Hardnesses of weld metals with A1100 and A5052 inserts are lower than those of the base metals. Grain size in the weld metal from butt welds made without inserts is larger than from butt welds with inserts of A1100 and A5052 in thin plates with thicknesses of 0.5 mm and 1.0 mm.

Segregation of Mg is found in the weld crack zone. In the case of A5052 insert metal, the formation of cracking is suppressed and thus the joint efficiency of welds is improved to about 90%. Whilst the absorbed impact energy of welds made without an insert shows a lower value than that of the base metal, toughness of the welds is improved by using A5052 insert metal.