Abstract Scope |
Additive manufacturing enables design and production of structural metallic components with complex geometries. Recent work has shown that, in addition to complex geometries, site-specific microstructures can be achieved through careful control of processing condition at every layer. The interactions between boundary conditions imposed by component geometry, wide variations of thermal signatures are brought about by mode of energy delivery, and composition of the alloys. These phenomena are studied using computer modeling, in-situ monitoring, and ex-situ characterization tools. The results from the above clearly show that the additive manufacturing is nothing but multipass micro-welding with complex boundary conditions and published theories and tools relevant to Integrated Computational Weld Models are quite relevant. This keynote will review case studies and associated fundamental challenges in extending these methodologies to wide range of structural metals and alloys. First study focused on control of crystallographic texture, during electron/laser beam powder melting, by controlling thermal gradient (G) and liquid-solid interface velocity (R). The sensitivity of columnar to equiaxed transitions in solidification maps was related to uncertainty of parameters used in the interface response function theories, as well as spatial and temporal variations in G and R. Second study focused on using melting experiments and post-process heat treatment as an alloy evaluation methodology. Microstructures in the melt regions of model aluminum and nickel alloys confirmed the feasibility of selecting wide range of solidification microstructures through spatial variations of G and R along the 3D melt pool surface, as well as stability of eutectic structures during post-process heat treatments. Extension of the above approach to solid-state additive manufacturing will also be introduced. Finally, the applications of additive manufacturing for various industries will be discussed. |