Powder Reuse and Its Effects on Laser Based Powder Fusion Additive Manufactured Alloy 718

Laser Based Powder Bed Fusion, a specific application of additive manufacturing, has shown promise to replace traditionally fabricated components, including castings and wrought products (and multiple-piece assemblies thereof). In this process, powder is applied, layer by layer, to a build plate, and each layer is fused by a laser to the layers below. Depending on the component, it appears that only 3-5% of the powder charged into the powder bed fusion machine is fused. Honeywell's initial part qualification efforts have prohibited the reuse of powder. Any unfused powder that exits the dispenser (i.e., surrounds the build or is captured in the overflow) is considered used. In order for the process to be broadly applicable in an economical manner, a methodology should be developed to render the balance of the powder (up to 97% of the initial charge weight) as re-usable. Though multiple manufacturers may be re-using powder, there is no industry standard methodology or practice for powder re-use. The present study (with 10 uses of the same powder lot) shows no appreciable impact on nickel-base superalloy 718 chemistry, powder size / distribution, or mechanical properties, with exception of gradual increase in oxygen content of the powder.