Characterization of IN 625 recycled metal powder used for selective laser melting

Abstract

Additive manufacturing of high-quality materials by Selective Laser Melting depends not only on establishing appropriate process parameters, but also on the characteristics of the metal powders used and their stability over time or after recycling. The aim of the research was to characterize the IN 625 powder used over multiple manufacturing cycles with a Lasertec 30 SLM machine. In order to achieve the research's goal, virgin and recirculated powder's physical and technological characteristics were investigated. A decrease in all D-values (D10, D50, D90) of the powder size distribution was observed after multiple recirculation cycles showing a decrease of the powder dimensional range over time. Both virgin and recirculated powders are composed of mainly spherical particles, but elongated particles and satellite particles were observed as well. The dimensional evolution analysis showed a deviation from the powder ideal roundness, deviation that is more pronounced over multiple recirculation cycles. It was experimentally determined that the powders present a good flowability based on the flow rate value obtained for both virgin and recirculated powders, confirmed also by the Hausner ratio and angle of repose.

Microstructural and Tensile Properties Anisotropy of Selective Laser Melting Manufactured IN 625

“…For microstructural analysis and tensile tests, prismatic specimens (10 × 10 × 15 mm 3 ) and cylindrical coupons 80 mm long and 11 mm in diameter were manufactured, using a DMG MORI, Lasertec 30 SLM machine (DMG MORI, Bielefeld, Germany) and IN 625 metal powder (15-45 µm particle range) produced by LPW Technology Ltd (Runcorn, UK) as feedstock. The powder's chemical composition is presented in Table 1, and it was characterized by the following powder size distribution: D 10 = 22 µm, D 50 = 34 µm, and D 90 = 42 µm, experimentally determined by the authors [42]. All specimens were manufactured on a heated building plate (80 • C) using the same process parameters: 250 W laser power, 750 mm/s laser speed, 40 µm layer thickness, 0.11 mm hatch distance, and 70 µm laser focus.…”

Manufacturing of Closed Impeller for Mechanically Pump Fluid Loop Systems Using Selective Laser Melting Additive Manufacturing Technology

“…Additionally, the influence of process parameters on the specimen surface roughness and material hardness was assessed. The main conclusion was that for 250 W laser power, 700-800 mm/s scan speed, and layer thicknesses in the range of 30-50 µm, the relative densities achieved are over 99.5%, as highlighted by the authors in [30][31][32]. However, during the manufacturing of the closed impeller and due to the appearance of the adherent dross on the interior side of the impeller, subjected to analysis in [33], the laser power was decreased to 200 W, which was found to be the best corrective measure.…”

Characterization, preparation, and reuse of metallic powders for laser powder bed fusion: a review

“…• AlSi10Mg [211] 904L [207] CoCrMo [200] • Reduction of small particles and interparticle forces [191] • Increase of particle size [211] Decrease 17-4 PH [212] Inconel 718 [42] Inconel 625 [202] • Reduction of particle sphericity [212] Marginal change AlSi10Mg [205] NA Among the various products from the interaction between laser and powders, powder oxidation is another form of powder degradation apart from spatters [213]. Though the whole L-PBF process is conducted under an inert gas atmosphere [1], the residual oxygen in the build chamber may still cause oxidation [214].…”