INFLUENCE OF GEOMETRICAL DESIGN ON FRICTION-WELDED AA6061/Ti6Al4V JOINTS FOR WING SPARS OF AIRCRAFT STRUCTURES

Abstract

In aerospace industry, there is a need for aluminum/titanium joints in wing spars of aircraft structures. This research explores the feasibility of joining Ti6Al4V to AA6061 by means of friction welding. Influence of geometrical design on the microstructure and impact strength of dissimilar AA6061/Ti6Al4V joints is investigated. Investigation by scanning electron microscopy reveals deformation of the grains at titanium side along the direction of stress, therefore leading to the formation of TMT (thermo-mechanically treated) zone. The intermetallic compound at the joint interface is attributed to the presence of brittle TiAl and Ti3Al phases. Rotational speed has a significant influence on the impact strength. The impact energy at the interface was found to be 10.2[Formula: see text]J when the speed of rotation was set as 1000[Formula: see text]rpm. Geometry featuring “spearhead with blunt end” is found to give good joint strength with minimum material loss. Fractography studies reveal the presence of few dimples in the welded zone and brittle mode of fracture.