As-deposited microstructure and tensile behavior of solid-state additive manufactured Ti–6Al–4V

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University of Alabama Libraries

Ti–6Al–4V (Ti64) is the most widely used titanium alloy on the market today due to its high strength-to-weight ratio and excellent corrosion resistance. Because of expensive Ti64 material costs, fusion based additive manufacturing (AM) methods are heavily utilized in the fabrication of Ti64 parts. This research presents the as-deposited properties and microstructure of Ti64 after additive friction stir-deposition (AFS-D): a layer-by-layer solid state AM process that provides the capability to produce fully dense, near-net shape parts from a variety of alloys, including Ti64. Microstructural characteristics of AFS-D Ti64 were determined using Electron Backscatter Diffraction (EBSD) and Energy Dispersive Spectroscopy (EDS). A Vickers hardness test measured the hardness of the AFS-D Ti64 deposition cross section. Quasi-static tensile experiments performed on as-built AFS-D Ti64 samples quantified the strength and ductility, and the results were compared to the data available in the open literature of Ti64 produced by other popular AM methods. In conclusion, the as-deposited AFS-D Ti64 performed as well as or better mechanically than cast and wrought Ti64, with a Vickers hardness of 348 HV and average ultimate tensile strength (UTS) of 1.2 GPa. Compared to other fusion based AM methods, AFS-D performed similarly, while possessing faster deposition rates with a more refined and equiaxed microstructure.

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Mechanical engineering, Materials science