Identifying combination of friction stir welding parameters to maximize strength of lap joints of AA2014-T6 aluminium alloy

Abstract

AA2014 aluminium alloy (Al–Cu alloy) has been widely utilised in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid-state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimise process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminium alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminium alloys. Hence, in this investigation, an attempt has been made to optimise friction stir lap welding parameters to attain maximum tensile strength using statistical tools such as design of experiment, analysis of variance, response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.