Analysis of mechanical properties and optimization of tungsten inert gas welding parameters on dissimilar AA6061-T6 and AA7075-T6 by a response surface methodology-based desirability function approach

Abstract

This study explores the influence of welding current, travel speed and gas flow rate on response parameters including ultimate tensile strength (UTS), percentage elongation (PE), microhardness (MH) and residual stress (RS) using face-centred central composite design (FCCCD). Dissimilar AA6061-T6 and AA7075-T6 plates were welded using an automated tungsten inert gas (TIG) process. Mathematical models were developed to predict the mechanical properties. High welding current or low travel speed enhanced the joint quality but raised residual stresses. At a welding current of 145 A, travel speed of 1.28 mm/s and gas flow rate of 18 l/min, the optimized UTS, PE, MH and RS were predicted to be 167.28 MPa, 10.25%, 69.61 HV and 65.49 MPa, respectively. Confirmation experiments were conducted to verify the model’s practicality. The results indicate that travel speed has the greatest influence on the responses, followed by welding current, while the gas flow rate has the least effect.