An experimental investigation on mechanical characteristics and wear behaviour of TIG welded dissimilar aluminum alloys

Abstract

The present research aims to investigate the combined influence of arc current and travel speed in terms of heat input during tungsten inert gas (TIG) welding and examine it through microstructural, mechanical, and wear characterizations. An automated welding setup was employed to fabricate the dissimilar AA6061-T6 and AA7075-T6 aluminum joints in a butt configuration. Macro and micrographic inspections were also conducted and investigated the changes across the weld cross-section with respect to heat input. Tensile, Charpy impact, residual stress, and wear tests were performed to examine the quality and strength of the joint. The results revealed that the joints with increased heat input displayed higher ultimate tensile strength, impact toughness, residual stress, and wear resistance. The consistent distribution of intermetallic phases and the fine equiaxed grains with minimal porosity development are probably responsible for it. However, excessive heat input caused reversion phenomena, coarser grains, and significant porosities, which reduced the tensile strength, impact toughness, and wear resistance of the joint. The welded sample S-3, having a welding current of 145 A, a travel speed of 78 mm/min, and a heat input of 1.67 kJ/mm, exhibited the highest ultimate tensile strength of 178 MPa, the largest elongation of 12.6%, the highest impact toughness of 13 J, and the lowest wear rate of 34 µm, along with a compressive residual stress of 60 MPa at the weld centre. The analysis of tensile and impact-fractured surfaces using SEM and EDS analyses validated the experimental results.