the forging counterpart of fusion-based additive processes

additive friction stir deposition offers a solid-state deformation processing route to metal additive manufacturing

in which every voxel of the feed material undergoes severe plastic deformation at elevated temperatures. In this perspective article

we outline its key advantages

e.g. rendering fully-dense material in the as-printed state with fine

equiaxed microstructures

identify its niche engineering uses

and point out future research needs in process physics and materials innovation. We argue that additive friction stir deposition will evolve into a major additive manufacturing solution for industries that require high load-bearing capacity with minimal post-processing.