Fundamentals of Friction Stir Welding, Its Application, and Advancements

Abstract

In friction stir welding (FSW) the material is welded without melting the base material. Aerospace, automobile, shipbuilding and electronics are some of the industrial sectors which use FSW for manufacturing of components. It is primarily used because of higher weld efficiency as compared with fusion joining processes. In this book chapter, the fundamental aspects of the FSW have been briefly discussed. The chapter also discusses the effect of input responses on the output responses, application of FSW in various industries, research advances in welding of similar and dissimilar material using FSW. The FSW tool has two major features namely, the shoulder and pin, as its shape and dimensions govern the material flow behavior. In general, a cylindrical tool is used for FSW. Tool rotational speed, tilt angle, welding speed, and plunge depth are the input conditions which affect the dynamics of the process. Changes in these parameters have an effect on axial force, spindle torque, temperature distribution/heat generation and strain. In addition, it ultimately changes the microstructural, hardness and weld strength. The choice of the workpiece and tool material for FSW is another big challenge as it has its own limitations. Application of FSW started with welding of aluminum and magnesium and its alloy but eventually, it gained traction in welding high-density metals like copper, titanium and steel. Welding of these materials requires a hard tool material with the better thermomechanical property as compared to the workpiece to avoid premature tool wear/failure. FSW is not only limited to similar metal welding but research is going for welding of material in the dissimilar configuration like aluminum with copper, magnesium with aluminum, and steel with aluminum etc. The successful evolution of FSW has led to the emergence of a few new variants of this technology such as friction stir additive manufacturing, friction stir processing, friction stir spot welding, and micro FSW.