In the present investigation, a dissimilar metal joint between Titanium alloy (Ti6Al4V, ELI) and pure Aluminium (Al) was achieved using an Al-Si based filler alloy by vacuum brazing technique. A sound dissimilar joint of Ti to Al was achieved after a series of pilot experiments with overlap configuration. A thin foil of 0.2 mm thick Al-Si was used as filler alloy. With an overlap of 7.5 mm, the average joint strength achieved was 64 MPa. Mechanical properties were evaluated by varying the overlaps of the vacuum brazed joints and then compared. The average joint strength achieved for an overlap distance of 3, 6 and 9 mm were 57 ± 0.5, 53 ± 0.5 and 59 ± 0.5 MPa, respectively. The brazed joints were investigated for macrostructure, microstructure, scanning electron microscope and electron probe micro analyser analysis for characterization studies.

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.