Titanium Recycling via MELD Metal Additive Manufacturing

The “buy-to-fly” ratio for titanium has been reported to be as high as 10 to 1 for some aerospace manufacturers, meaning that for every 10 pounds of titanium purchased, 1 pound finds its way to the finished product. The remaining material is recycled or sold as scrap. The ability to reduce this buy-to-fly ratio has created a strong aerospace interest in metal additive technologies in recent years. The ability to use recycled titanium material as a feedstock could present an attractive opportunity for these aerospace manufacturers. MELD technology is a solid-state, thermo-mechanical AM process that yields fully-dense products with near wrought properties, reduced distortion, high deposition rates, and significantly faster throughput as post deposition material-processing (HIP, sintering, etc.) is not required. During the MELD process, filler material is forced to flow between the rotating MELD tool and the substrate, whereby the filler material undergoes severe plastic deformation, dynamic recrystallization, and deposition. MELD can be used for the deposition of metal, metal matrix composites (MMCs), thermoplastics, etc. Due to its additive nature, MELD can be used for coating, repair, joining, or additive manufacturing applications of both similar and dissimilar materials. MELD is differentiated from other AM technologies because it is a highly scalable, open-atmosphere process with a high deposition rate that offers flexibility with material sets and yields a near wrought microstructure on near-net-shape complex 3D structures. MELD has successfully demonstrated the use of recycled aluminum battlefield scrap as a feedstock for metal AM. In this presentation, a review of the use of recycled materials for feedstock used in the MELD process will be presented. Recent demonstrations of using recycled titanium material as feedstock will be presented as the main focus of this work, including a discussion on microstructure, chemical analysis, and mechanical properties.