Study and effect of GTAW parameters on mechanical properties of aluminium dissimilar welded joints: optimization technique

In this research, dissimilar metals of AA 6082 and AA 7075 are joined using Gas Tungsten Arc Welding (GTAW) process with ER4043 filler wire. The welding conditions and their range are identified for producing quality welding characteristics. Taguchi based techniques are adopted for design of experimentation and analyzing factors involved in welding characteristics. L-9 Orthogonal Array (OA) was used for Design of Experiments (DOE). Welding current, filler diameter and root gaps are selected as input parameters. The welded structure defects were inspected with X-ray radiography images as well as macrostructures. The response factors such as Ultimate Tensile Strength (UTS), % of elongation, hardness and impact strength were considered and evaluated by conducting mechanical tests. Analysis of Variance (ANOVA) is conducted to study the influence of parameters on responses. The tensile strength of sample 5 is increased by 53.37% when compared with the sample 6 due to the lower heat input rates. The welding speed (68%) has most influence parameter followed by welding current (14%) and filler diameter (14%). The dissimilar combination of aforementioned joints have wide range of application including aerospace, defense, and military sectors.