Additive friction stir processing and hybrid metal additive manufacturing of high melting point materials: A review

Ever since the beginning of 4th industrial revolution, metal additive manufacturing has revolutionized the paradigm of printing high melting point materials. In this context, this paper reviews experimental and computational aspects of friction stir processing and hybrid techniques applied for metal additive manufacturing of high melting point materials like steel, and titanium alloys. Initially, friction stir processing working principle has been discussed. Secondly, friction stir processing is compared with other severe plastic deformation techniques and summarized their advantages, disadvantages and applications in a tabular form. Then based on the state-of-the-art of literature, additive friction stir processing and hybrid metal additive manufacturing processes are discussed for high melting point materials and results have been presented with respect to their microstructural developments, mechanical behavior, etc. Finally, gaps are highlighted for high melting point materials that shows importance of selecting process parameters, tooling capacity, computational analysis, mathematical modelling, etc., and presented these as future scope of work.