XPS, XRD, and SEM characterization of the virgin and recycled metallic powders for 3D printing applications

Abstract We characterized the surface and microstructure of both feedstock (virgin) and recycled Stainless Steel 316L powders used for selective laser melting process. Reusing the recycled powders can significantly reduce the powder consumption, production cost and time. We have performed X-ray photoemission spectroscopy (XPS), Scanning electron microscopy (SEM), X-ray Diffraction (XRD) and rheology analysis on steel powders both on the virgin powder and the powders not adhered to the printed parts but recycled in the powder bed. The results confirm that the oxygen level on the surface of the recycled powder is increasing and the metallic oxides diffuse out to the surface of the powder particles during the manufacturing process. Nevertheless, the changes are not significant which promise the reusability of the recycled powders for several cycles. We observed no change on the phase of the recycled powder. Further characterizations are ongoing to measure the chemical composition and morphology of both virgin and recycled powders to correlate them with the mechanical properties of the printed parts. These characterizations allow extending the powder reuse for a number of reusing cycles and reducing the manufacturing time and cost without reducing the mechanical properties of the final parts.