Process parameter optimization in friction spot welding of AA5754 and Ti6Al4V dissimilar joints using response surface methodology

This study shows experimental and numerical results of friction spot welding of AA5754 and Ti6Al4V alloys. The determination of proper welding parameters plays an important role for the weld strength. Experimental tests, conducted according to combinations of process parameters such as tool rotational speed (RS) and dwell time (DT), were investigated with response surface methodology using a 3(k) factorial design of experiments. Sound joints with elevated shear strength were achieved and the influence of the main process parameters on joint strength evaluated. DT was the parameter with the largest influence on the joint shear resistance (58.9 %), followed by its interaction with RS (38.1 %). Higher strength was correlated to the thickness and morphology of the joint interface. A numerical model for predicting lap shear strength was successfully developed and used to optimize welding parameters in order to produce high-performance joints with less energy consumption and high efficiency.