Influence of Inconel 625 alloy powder reusing on feedstock characteristics and mechanical properties of deposited parts

Low utilization efficiency of powders limits the large-scale application of Laser Melting Deposition (LMD) and discussions on this topic are far from enough. So, this study was done with the aim to enhance powder reuse. Changes of Inconel 625 powders (compositions, morphology, size, flowability and sphericity etc.) in the 4 times of reusing were clarified. And the resulted effects on microstructures, inclusions and mechanical properties (microhardness and tensile properties) of deposited parts were also elucidated. It was found that reused powders were severely oxidized and indicated poorer flowability, with particle sizes increased after 1 and 2 times of reusing while decreased after 3 and 4 times of reusing. Number densities of inclusions in the deposited parts increased while grain sizes decreased in the powder reusing. Obvious changes in microhardness and tensile strength in deposited parts were not seen but the ductility only slightly decreased. The obtained results were meaningful to indicate that powder reusing was feasible, which would help save resources and reduce costs, thus to promote the competition of LMD.