A critical review on process metrics-microstructural evolution-process performance correlation in additive friction stir deposition (AFS-D)

In the recent past, additive friction stir deposition (AFS-D) has evolved into one of the promising additive manufacturing (AM) techniques for the fabrication of near-net-shaped metal 3D structures since they possess several notable benefits such as good inter-layer mixing; equiaxed, homogeneous, and refined microstructure; and isotropy. Nevertheless, significant deviations from the ideal microstructural evolution and mechanical performances of the deposits are also reported in the state-of-the-art AFS-D research. These deviations are found to be dependent on the process metrics such as the process parameters; tool design; feedstock materials; print location, and geometry. Therefore, it is a need of the hour to critically review the 'process metrics-microstructure-mechanical performance' correlation in the AFS-D to help the industry and the research community for acquiring further insight, which lacks recognition to date.

Automated summary

In recent years, additive friction stir deposition (AFS-D) has become a promising technique for fabricating near-net-shaped metal 3D structures. However, there are deviations from the ideal microstructural evolution and mechanical performances, which are affected by process metrics such as process parameters and tool design. Therefore, it is important to study the correlation between process metrics, microstructure, and mechanical performance in AFS-D.