Ultrasonic spot-welding of AA 6061-T6 aluminium alloy: Optimization of process parameters, microstructural characteristics and mechanical properties of spot joints
P. Rajalingam, S. Rajakumar, S. Kavitha, Tushar Sonar
Abstract
The main objective of this investigation is to optimize the ultrasonic spot welding (USW) parameters specifically welding time, amplitude and pressure for enhancing the tensile shear fracture load of lap joints of AA 6061-T6 aluminium alloy for automotive applications. The statistical response surface methodology (RSM) was utilized for generating strength prediction models (SPM) and validated using analysis of variance (ANOVA). The response surfaces were created using RSM and analyzed. The effect of USW parameters on macrostructure, microstructure and tensile fracture load (TSFL) of USW joints was studied. From the results, it was observed that the USW joints created using the welding amplitude of 100%, welding time of 21 s and welding pressure of 6 bar exhibited greater TSFL capacity of 5.08 kN. The SPM accurately predicted the TSFL of USW joints within 5% error on 95% confidence. Welding pressure disclosed major effect on TSFL of USW joints followed by welding amplitude and time. The greater TSFL of USW joints is imputed to the better coalescence of weld surfaces and refined microstructure.