The Effect of Adding Magnesium to the Filler Material on the Tensile Properties of TIG Welded AA 6082 Aluminium Alloy

Aluminium 6082 is a moderate strength alloy with good weldability. Tungsten inert gas (TIG) welding is the most common welding process of this alloy. AA6082 is one of the major alloys used in automotive, shipbuilding, aircraft and structural applications. Tensile strength of welded joints is an important design parameter when it is used for these applications. ER 4043, which contains 5% silicon as major alloying element and ER5356, which contains 5% magnesium as major alloying element, are the most common filler materials used for the welding of AA6082 alloys. In the present investigation, magnesium is added to siliconbased ER 4043 filler wire at different percentage levels, and this new filler wire with altered chemical composition is used for welding of 6082 aluminium plates. The effect of adding magnesium to the filler wire is investigated by using design of experiments. From experiments it is found that this new filler wire is capable of providing higher tensile strength for the welded joint. It is found that the increase in the tensile strength is due to the formation of magnesium silicide intermetallic phase in the weld zone. The presence of various intermetallic phases are identified by microstructural analysis. The amount of magnesium content in the new filler wire which will give the maximum tensile strength to the joint is optimized by using factorial design, artificial neural network and genetic algorithm.