Features of Structure and Properties of Lap-Welded Joints of Aluminum Alloy Al–4Cu–1Mg with Titanium Alloy Ti–6Al–4V, Obtained by Friction Stir Welding

Abstract

Lap-welded joints between Ti–6Al–4V and Al–4Cu–1Mg were obtained using water-cooling-bath friction stir welding at different FSW tool rotation rates. The increase in the tool rotation rate from 350 to 375 RPM leads to better plasticization of the titanium alloy, elimination of stir zone defects, better interlocking and bonding with the aluminum alloy as well as the formation of intermetallic Al–Ti compounds (IMC), preferentially of the Al3Ti type. Shear-loading testing showed the best result was at the level of 3000 N with 2 mm of displacement. Increasing the FSW tool rotation rate to 400 and 450 RPM resulted in the formation of more IMCs, which had a detrimental effect on both maximum load and displacement achieved in the shear tests.