Additive manufacturing of Inconel-625: from powder production to bulk samples printing

PurposeFor metal additive manufacturing, metallic powders are usually produced by vacuum induction gas atomization (VIGA) through the breakup of liquid metal into tiny droplets by gas jets. VIGA is considered a cost-effective technique to prepare feedstock. In VIGA, the quality and the morphology of the produced particles are mainly controlled by the gas pressure used during powder production, keeping the setup configuration constant. Design/methodology/approachIn VIGA process for metallic additive manufacturing feedstock preparation, the quality and morphology of the powder particles are mainly controlled by the gas pressure used during powder production. FindingsIn this study, Inconel-625 feedstock was produced using a supersonic nozzle in a close-coupled gas atomization apparatus. Powder size distribution (PSD) was studied by varying the gas pressure. Originality/valueThe nonmonotonic but deterministic relationships were observed between gas pressure and PSD. It was found that the maximum 15-45 mu m percentage PSD, equivalent to 84%, was achieved at 29 bar Argon gas pressure, which is suitable for the LPBF process. Following on, the produced powder particles were used to print tensile test specimens via LPBF along XY- and ZX-orientations by using laser power = 475 W, laser scanning speed = 800 mm/s, powder layer thickness = 50 mu m and hatch distance = 100 mu m. The yield and tensile strengths were 9.45% and 13% higher than the ZX direction, while the samples printed in ZX direction resulted in 26.79% more elongation compared to XY-orientation.

Automated summary

Metallic powders for additive manufacturing are usually produced by vacuum induction gas atomization (VIGA), where liquid metal is broken into tiny droplets by gas jets. In this study, Inconel-625 feedstock was produced using a supersonic nozzle in a close-coupled gas atomization apparatus. The relationship between gas pressure and powder size distribution was found to be nonmonotonic but deterministic, with the maximum 15-45 μm percentage achieved at 29 bar Argon gas pressure. Tensile test specimens printed with the produced powder showed higher yield and tensile strengths in the ZX direction and increased elongation in the ZX direction compared to the XY orientation.