INVESTIGATION ON PULSED CURRENT GMA WELDING OF Al~Li ALLOY

Abstract

Aluminium-Lithium alloys are widely used in aero space applications because of their lower density and higher elastic modulus compared to conventional structural Aluminium alloys. In aircraft structures, the weight saving achieved by using low density alloys are expected to greatly save the fuel besides increasing the performance. Welding can be effectively used to fabricate these structures provided a suitable process and procedure is developed to ensure desired properties of the welded. The present investigation has been carried out on an Al-Li alloy, Russian grade 1441, by using Continuous current GMA. welding and Pulsed current GMA welding process. By varying the welding current and welding speed, the effect of heat input on metallurgical and mechanical properties of weld joints has been studied and compared. The mechanical properties those tested are as tensile strength of the welded joint, with and without reinforcement, and microhardness (VHN). The weld joints are also characterized by studying their geometry, dilution, porosity content and microstructure. Finally, the characteristics of the welds are compared to find out a suitable technique of joining of this Al-Li alloy for improved joint properties.