Establishing the Relation Between Properties, Microstructures, and Processing Parameters in Innovative Eccentric Friction Based Additive Manufacturing

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The application of additive manufacturing (AM) technologies continues to increase as they reduce manufacturing costs and eliminate/reduce the need for subsequent machining and assembly. The properties of AM parts involving the melting of materials are influenced by rapid solidification, which affects the microstructure. Despite extensive research, fundamental challenges persist, including solidification induced porosities, large thermal gradients, residual stresses, non-homogeneous grain structure, and hot cracking. Therefore, solid-state AM methods, including additive friction stir manufacturing, are being developed, which combine layer-by-layer AM technology with solid-state friction stir welding to address these issues. However, the technique is typically limited to the fabrication of large near-shaped parts and selective area reinforcement for large-scale applications. This research program aims to develop a novel eccentric friction-based AM technique equipped with heaters, allowing feed of small diameter wire materials for narrower deposition of AM layers with higher precision than conventional additive friction stir manufacturing. Therefore, the entire cross-section of the feed material slides against the substrate with a uniform linear velocity and contributes to frictional heating due to the eccentricity of the feed material, depositing AM layers with minimum defects and uniform microstructure and properties. The experimental setup will also be applied to an in-situ configuration incorporating a sapphire substrate and a high depth-of-focus microscope to observe and study the detailed deformation mechanisms in the deformation zone during AM deposition process. This research will systematically study the micromechanisms by which the material deforms and transfers to the substrate/layers and their effects on the microstructure, the porosity/defects, the mechanical properties, corrosion, and wear resistance of the deposited AM layers to establish the relationships between the process parameters and properties of AM Parts. In summary, the results will be used to reduce the cost and increase the efficiency and quality of the metal AM processes by improving the microstructure (through in-situ deformation of the deposited layer) and controlling the strain and strain rate (through texturing, rotational speed, eccentricity, temperature and feed rate of the FM). The program will train nine highly qualified personnel.