Aluminum Friction Stir Weldbonding

Abstract

The push towards lightweight efficient structural design has led to an increasing interest in joining technologies for aluminum alloys. Although the use of these alloys has previously been restrained by production difficulties associated with their poor welding properties, friction stir welding and adhesive bonding allowed for a larger flexibility in lightweight structural design. In this work a combined joining process of this welding technique with adhesive bonding (friction stir weldbonding) is presented. Quasi-static mechanical properties, fatigue behavior and other properties of the friction stir weldbonding joints were assessed and compared with adhesive only and welded only joints.Friction stir welding (FSW) is a revolutionary joining method that allowed welding of previously unweldable alloys with excellent characteristics, and has an enormous potential for application in a large array of industries. Even though friction stir welding presents several advantages over other welding techniques when regarding joining of aluminum alloys, it also presents its share of challenges. For example, in the case of overlap configuration joints, which are very common in structural design, the presence of a hook defect reduces the static and fatigue strength as this defect acts like crack initiation point. In certain alloys the question of chemical corrosion is also a factor requiring good sealant measures to avoid degradation.The combination of FSW with adhesive bonding (AB), forming friction stir weldbonding may present itself as a solution for these concerns. The development of this new joining technology aims at incorporating properties and characteristics of both joining technologies, as well as improving damage tolerance. FSW is able to produce consistent joints with high static strength, while the adhesive will not only allow improved vibration damping and fatigue strength but may also serve double duty as a sealant, isolating the weld from the environment. Damage tolerance is improved, by having to failure mechanisms, cohesive rupture in the adhesive and ductile and shear failure in the aluminum.