Effect of process parameters on mechanical properties and microstructure of TIG welded joints between AA 5052-T0 and AA 7075-T0

Tungsten Inert Gas (TIG) welding has wide area of application in various industries like automobiles, aerospace and marine, etc. In TIG welding, welding parameters play a vital role in creating a strong welded joint. This research work was focused on investigation of effect of current, gas flow rate and filler rod diameter on mechanical properties and microstructure of AA 5052-T0 and AA 7075-T0. Electrode rod (ER) 4043 was used as a filler material. Experiments were conducted on a 1.5 mm thick sheet of AA 5052-T0 and AA 7075-T0 and were designed according to Taguchi method. The effect of welding parameters was studied on tensile strength, flexural strength (face and root), microhardness and microstructure. Statistical analyses were carried out through signal to noise ratio, analysis of variance and regression approach. It was found that maximum tensile strength obtained was 193.2MPa at current of 70A, gas flow rate of 11L/min and filler rod diameter of 2.4mm. Moreover, highest face bend strength examined was 382.3MPa at current of 70A, gas flow rate of 11L/min and filler rod diameter of 2.4mm. Maximum root bend strength obtained was 271.41MPa at current of 70A, gas flow rate of 11L/min and filler rod diameter of 2.4mm. Whereas, maximum hardness at weld zone was 77.1HV at current of 60A, gas flow rate of 11L/min and filler rod diameter of 1.6mm. Current appeared as most influential parameter in this research work. Microstructure examination showed coarse and continuous grain network in weld zone at high current level.