ABSTRACT
Friction stir welding–based additive techniques can be commonly termed friction stir additive techniques. These are an innovative approach aimed toward utilizing the principle of layer-by-layer additive manufacturing with solid-state FSW techniques and are a major breakthrough in the domain of the metal additive manufacturing sector. These are basically a special class of friction-based additive techniques. They produce components with superior structural and mechanical properties. Friction stir additive manufacturing, friction assisted (lap) seam welding–based methods, and additive friction stir are three most effective FSATs. In FSAM, layer-by-layer addition is performed using FSW. It effectively overcomes the drawbacks of low shear strength of MAM technologies and can effectively fabricate fully dense components in a solid state with improved structural performance. In FSAW, the addition of layers takes place owing to deformation caused by pinless tools. In AFS, material is added in the form of layers from the center of a nonconsumable tool. AFS effectively overcomes the drawbacks of layer welding methods and produces components possessing reduced granular sizes amounting to wrought homogeneous microstructural properties. This chapter introduces the basic principles of FSAM, FASW, and AFS along with their general features and the status of research in these areas.
