A limited examination of the static and fatigue properties of some welded sheet materials based on the Al:Zn:Mg system

摘要

Welds made by the argon arc and electron beam processes in Al:Zn:Mg alloys in thin sheet form were subjected to static and fatigue tests. Very good static properties were developed by using a simple post weld precipitation treatment (not full heat treatment). The fatigue properties of naturally aged, dressed butt welds in Al:Zn:Mg alloys, were only slightly superior to those for similar joints in the standard alloy N8 used for comparison. An improvement of more than 3596 on these properties could be obtained, however, by a post weld precipitation treatment, giving fatigue strengths more than 25% higher than any previously recorded for welds in aluminium alloys. Some correlation was found between the improvement in properties and the structure of weld metals as observed under the electron microscope. One of the alloys tested contained 2% copper, but the results showed this addition to be of doubtful advantage.