Session: 16-02-01: Microstructure II

Paper Number: 173579

Recycled Feedstock From Machine Swarf - Material Characteristics and Influence on Processing 

Ti alloys, known for their strength and flexibility, are essential in fields such as aerospace and aviation. However, materials like Ti alloys face several challenges throughout their life cycle, including sourcing them from geo-political sensitive areas and in their low recyclability. In addition, atomizing Ti alloys for additive manufacturing (AM) feedstock is an energy and cost intensive process. The ability to use Ti alloy waste as AM feedstock, whether as reused powder from previous process uses or from machine scrap, reduces the environmental impact, promotes industrial symbiosis, circular economies, and a resilient supply chain. This talk investigates the influence of unconventional feedstock from Ti alloy waste on the metal additive manufacturing process.

In particular, this talk focuses on the laser directed energy deposition process (L-DED), and how these powder feedstocks of varying chemical compositions and morphologies impact the fabrication, repair, and remanufacturing of copmlex components. Powders from recycled Ti alloys are expected to behave differently during printing when compared to commercial Ti powders due to their irregular shape and chemical composition, which may influence the resulting microstructure and material properties. The methodology used combines optical imaging of the melt pool surface during the process, along with high-speed synchrotron techniques conducted at Brookhaven National Laboratory's National Synchrotron Light Source II and Argonne National Laboratory's Advanced Photon Source. Ultrafast X-ray imaging and diffraction allows for the examination of points at various distances from the melt pool in single and multilayer builds to provide insight into the transition from liquid to beta, beta to alpha or martensitic phases as wells as changes in these phases due to thermal cycling, along with changes in melt pool flows with different compositions of feedstock. The data acquired from these experiments will allow comparisons of phase formation and phase fractions to be made between commercial and recycled powdered feedstocks as a result of heat input, mass flow rate, powder morphology, and compositional variations. Data acquired from these experiments will be substantiated with electron microscopy and material property analysis to accurately compare the printability and dynamics of the recycled feedstocks as compared to commercial feedstock. Preliminary results have shown that powder feedstock morphology impacts the flowability and melt pool fluctuations during the process, which leads to more frequent grain nucletion. In addition, chemical composition of feedstock leads to shifts in cooling rates. Lastly, the collected data will contribute to the optimization of the L-DED process for depositing recycled Ti powders and establish accurate simulation to predict the behavior of the microstructure.

Presenting Author: Sarah Wolff The Ohio State University

Presenting Author Biography: Dr. Sarah Wolff is an assistant professor in the mechanical and aerospace department at The Ohio State University. She graduated from Northwestern University in 2018 with a PhD in mechanical engineering and in 2013 with a BS in environmental engineering. She was awarded the 2022 SME Sandra L. Bouckley Outstanding Young Manufacturing Engineer and the 2025 NSF CAREER award. Dr. Wolff is a CIRP research affiliate and an associate editor for Additive Manufacturing Letters.

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