Mechanical properties and microstructural characterization of automated pulse TIG welding of dissimilar aluminum alloy

Abstract

Tungsten inert gas (TIG) welding is commonly used welding process for joining aluminum alloys. Welding of aluminum and its alloys poses several problems to the designer as they are prone to hot cracking and porosity. To overcome this, a relatively new automated TIG welding with continuous wire feed arrangement is employed for joining two dissimilar aluminum alloy with pulse TIG welding. Trial runs were conducted on dissimilar aluminum alloy 5083 and 6061 plates of 6.35 mm. Radiography studies were done to check porosity and lack of penetration. The microstructure, mechanical properties and surface morphology at the fractured location of the weld joint were examined. The microstructural properties of base metal, heat affected zone and fusion zone were analyzed through optical microscopy. The welded joints show an ultimate tensile strength of 213 MPa, yield strength of 176 MPa and elongation of 12%. Energy dispersive spectroscopy was conducted to examine intermetallics composition in fusion zone while fractured surface was examined using scanning electron microscopy (SEM). SEM images show dimple type rupture present at the surfaces owing to insufficient or excessive heat with impurities that prevents the accomplishments of stronger micro-level weld integrity.