Strength and Fatigue Resistance of Laser-MIG Hybrid Butt Welds of an Airframe Aluminium Alloy AA6013

Abstract

Hybrid welding is, as regards selection of welding parameters, a tolerant process. On the other hand, the weld seam and the heat affected zone may tend to be wider as in an arc process, which may be detrimental to mechanical stability. With CO2 laser beam buttwelds as a basis for comparison, properties of butt-welds of a peak-aged airframe alloy AA6013-T6/3.2 mm, produced by Nd:YAG-MIG hybrid, are investigated. A filler wire (AA4047; AlSi12) was used for both types of welding. It is found that the hybrid process coarsened the microstructure in the fusion zone partly. Furthermore, although the weld seam and the heat affected zone were wider, mechanical properties were not at all adversely affected. Changes in hardness and tensile strength were marginal and the fatigue performance was in fact improved for the hybrid welds. These results are presented and discussed. It is concluded that the hybrid welding deserves consideration for fatigue critical applications.