Dissimilar joining of titanium to aluminum using friction stir welding process and weld joint characterization

Abstract

Abstract The present investigation studies the solid-state joining of difficult-to-weld aerospace materials such as titanium alloy (Ti6Al4V, ELI) and pure aluminum. Due to the wide difference in thermo-mechanical properties, it was a challenging task to establish a dissimilar metal joint. The friction stir welding process with a conically shaped tungsten carbide tool was used in the present investigation to join the dissimilar titanium alloy and aluminum in the lap joint configuration. After a series of pilot experiments, the optimum test conditions to produce the defect-free joint are spindle speed of 1200 rpm, feed rate of 40 mm min−1, tool tilt angle of 1°, and 1 mm tool offset towards the aluminum side. The results show that a good joint was achieved with a maximum joint strength of 89 MPa. The dissimilar joints are characterized by macrostructure, microstructure, microhardness, and scanning electron microscopic analysis.