Gas tungsten arc welding studies on similar and dissimilar combinations of Al-Zn-Mg alloy RDE 40 and Al-Li alloy 1441

Abstract

The present study is concerned with gas tungsten arc welding of two high strength aluminium alloys, namely, an Al-Zn-Mg alloy (RDE 40) and an Al-Li based alloy of Russian grade 1441. One of the critical requirements of these two alloys is that they should be weldable. In the present work, weldability aspects of these alloys were studied in terms of solidification cracking tendency, microstructure, tensile properties, and microhardness across the welds. These studies were extended to dissimilar welds between RDE 40 and 1441 produced via conventional gas tungsten arc (GTA) welding as well as pulsed current GTA welding. It was found that RDE 40 welds were less sensitive to solidification cracking and weld metal porosity compared with 1441 alloy. The superior weldability of RDE 40 was related to the equiaxed nature of the fusion zone and a lower sensitivity to moisture pickup. It was possible to produce RDE 40-1441 welds without defects. Pulsed current welding of RDE 40 to 1441 showed improved mechanical properties compared with conventional GTA welding, and these were related to the refinement of the fusion zone microstructure.