ABSTRACT
The majority of commercially prevalent additive manufacturing techniques are fusion-based processes. Owing to the accompanying liquid solid phase transformation in these techniques, they suffer from metallurgical discontinuities and solidification-related defects. To overcome the limitations of fusion-based AM processes, solid-state friction-based additive techniques offer better alternatives to additively manufacture metallic materials. There are seven main processes under this class of FATs, which is discussed in Chapter 3. Two processes based on friction deposition, that is, friction deposition and friction surfacing–based AM processes, are covered in detail in this chapter. Both these processes are similar in principle, as, in both techniques, deposition of material takes place from a consumable rod. In friction deposition, the addition of layers takes place at once, while in the latter case, the addition takes place from a rotating consumable rod when the substrate traverses in the defined direction. These techniques can produce 3D parts with better mechanical properties as compared to conventional AM processes and their respective base materials. In this chapter, the principles of AM via these techniques and their characteristics are discussed through an examination of different experimental studies.
