Recycling of Titanium Alloy Powders and Swarf through Continuous Extrusion (ConformTM) into Affordable Wire for Additive Manufacturing

Sarah A Smythe,Ben M Thomas,Martin Jackson

doi:10.3390/met10060843

Abstract

Over the last 20 years, there has been growing research and development investment to exploit the benefits of wire deposition additive manufacturing (AM) for the production of near-net shape components in aircraft and space applications. The wire feedstock for these processes is a significant part of the overall process costs, especially for high-value materials such as alloyed titanium. Powders for powder-based AM have tight specifications regarding size and morphology, resulting in a significant amount of waste during the powder production. In the aerospace sector, up to 95% of forged billet can be machined away, and with increasing aircraft orders, stockpiles of such machining swarf are increasing. In this study, the continuous extrusion process—ConformTM—was employed to consolidate waste titanium alloy feedstocks in the forms of gas atomised powder and machining swarf into wire. Samples of wire were further cold-drawn down to 40% reduction, using conventional wiredrawing equipment. As close to 100% of the waste powder can be converted to wire by using the ConformTM process. This technology offers an attractive addition to the circular economy for manufacturers and, with further development, could be an important addition as industries move toward more sustainable supply chains.

Highlights

In recent years, there has been significant attention on the use of powder-based additive manufacturing in the production of components in the aerospace, medical and automotive sectors.The ability to produce near-net shape components at a faster rate and with less material waste is a clear advantage of these processes; they require high-quality spherical powders [1] to produce high-quality components
This paper describes a solid-state method forwire, consolidating out-of-specification titanium powders powders and waste swarf titanium directly into which, after subsequent wiredrawing, could be used in metal deposition
Three materials were during this work: grade commercially pure titanium hydridehydride-dehydride

Summary

Introduction

There has been significant attention on the use of powder-based additive manufacturing in the production of components in the aerospace, medical and automotive sectors.The ability to produce near-net shape components at a faster rate and with less material waste is a clear advantage of these processes; they require high-quality spherical powders [1] to produce high-quality components. An increase in powder production to supply the AM sector comes with the inevitable generation of unusable waste material. This relates to powders which are non-spherical, too small/large for the process, or that have already been AM processed and cannot be reused due to an increase in interstitial elements such as oxygen and nitrogen. In the case of gas atomisation, up to 65% of the powder [3] could be out of specification for powder-based additive manufacturing processes. Many AM powder producers are stockpiling powder and need alternative recycling options in order to make AM processes more sustainable

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