Effect of rotational speed on Ti-6Al-4V-AA 6061 friction welded joints

Joining of Ti-6Al-4V to AA6061 has tremendous applications in aerospace, automotive and medical industries. Dissimilar Ti-6Al-4V/AA6061 of fluid coupler in aircraft industries are recently made employing friction welding technique. In this research work, experimental investigation on the effect of rotational speed on the quality of integrity of dissimilar Ti-6Al-4V/AA6061 joints was carried out. Effect of the most important process parameter, rotational speed on the mechanism of bonding at the interface is investigated by observing changes in microstructure of the welded specimen. Increase in rotational speed raises frictional heating at the interface and leads to dynamic recrystallization with recovery of recrystallized equiaxed grains which is highly favourable for enhancing joint strength. Increase in micro hardness at the weld line of the joint interface may be attributed to the formation of intermixed zone compound, which is brittle in nature. The rotational speed causes the tendency of formation of Ti3Al, TiAl at the joint interface. Experimental results of mechanical testing such as tensile strength and impact strength reveal that enhanced joint strength could be achieved with 1000 rpm as rotational speed. Micrograph at fractured surface shows river pattern with few dimples. Tensile strength as much as 186.59 MPa could be achieved using this technique.