Effect of Aluminum Arc Butt Joint Weld Geometry on Fatigue Strength

Abstract

The use of aluminum in auto odies is increasing due to the requirement of mass reduction for gas mileage enhancement. However, few open studies have been conducted on the fatigue strength of arc welded aluminum butt joints. In this study, the fatigue strength of arc welded butt joints of aluminum sheets was investigated. The material was 6061-T6 with a thickness of 4 mm. Welding specimens were prepared to determine the effects of the top bead toe angle, penetration depth, top surface misalignment, and alternative double-butt joint formation. Results showed that the top surface misalignment and partial penetration were more critical than the top bead toe angle on fatigue strength. Partial and full penetration revealed the lowest and highest fatigue strength, respectively. Because of the low viscosity and surface tension, achieving full penetration in butt joint aluminum arc welding without a backing component while also controlling penetration depth are impossible. An alternative solution to this problem is to ap-ply a double-butt joint design, with experimental results showing for the first time the validity of this solution in terms of fatigue strength. Key words: Aluminum, Arc, Welding, Fatigue, Automotive, Butt joint