Electrical characterization of 316L metal powder used in additive manufacturing

Filbert, Joseph
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This research explores the feasibility of using the electrical properties of a metal powder to characterize the overall quality of the powder for use in powder bed fusion additive manufacturing. Feed powder which is recycled over multiple build cycles will no longer build quality parts; manufacturers and operators are interested in the ability to measure the powder degradation over time, to determine when the feed powder needs to be replaced or refreshed. The effects of reuse have been monitored using both chemical and mechanical characterization tests. The characterization tests investigate the particle size distribution (PSD), density, morphology, and surface chemistry of the feed powder. Additionally, strength and ductility of the built parts have also been assessed using mechanical testing, allowing correlation of the feed powder properties with the built part quality. Mechanical and chemical testing is expensive and time consuming. It is hypothesized that changes to the electrical properties of feed powder from reuse offers a pathway to in-line monitoring of feed powder quality. As a first step to developing an electromagnetic nondestructive evaluation method, broadband dielectric spectroscopy (BDS) measurements of wax-based metal powder composites were conducted. Seven different stainless-steel powder samples were prepared by altering their PSD, morphology and surface chemistry. It was shown that changes in PSD, morphology, and surface chemistry could be detected using BDS. These results will aid in the development of an in-line capacitive sensor for monitoring feed powder quality.

additive manufacturing, nondestructive evaluation, powder characterization