Abstract Scope |
Despite salient advances over the last decade, fusion-based additive manufacturing, e.g., powder bed fusion and directed energy deposition, inevitably compromises the control of porosity, residual stress, and hot cracking due to the liquid phase bonding mechanism. As an emerging solid-state additive technology, additive frictions stir deposition (also known as the MELD technology) leverages rapid, severe plastic deformation to enable location-specific deposition without melting the feed material. The configuration of additive friction stir deposition is similar to fused deposition modeling; but to facilitate rapid deformation and deposition of metals, frictional heating is employed. Thanks to the compression and shear stress-states as well as the extensive material flow during deposition, the as-deposited material is typically fully-dense with fine, equiaxed grain structures and forging-like mechanical properties. In this talk, I will discuss the state-of-the-art understanding of the underlying process fundamentals based on in situ monitoring of thermal field evolution, material flow, and feeding force and torque evolution. Niche applications in structural repair, aluminum upcycling, selective-area cladding, and dissimilar material 3D printing are also highlighted. |