Influence of laser DMD techniques on microstructure of Inconel 718 high-temperature alloy

Direct Metal Deposition (DMD), combined with CAD/CAM technology, material powder metallurgy technology, optics technology, is an effective method of rapid manufacturing, which can be used to control the properties of metalwork by controlling the microstructure of metal deposition layer. As a high-temperature nickel-base alloy containing high Nb, Inconel 718 is widely applied in the key parts of aerospace engines in virtue of its excellent high-temperature intensity, antioxygenic property, hot corrosion resisting property, fatigue resistivity and rupture resistivity. Laser DMD technology supplied a new way for the direct manufacture and reparation of the complex parts made of Inconel 718. The laser DMD experiments were performed on Inconel 718 in this paper, the microstructure in different laser processing parameters were researched and analyzed by SEM and EBSD, and the DMD process variables were optimized. And the influence on the growth of crystal grain of laser deposition layer under different molten pool temperature was discussed as well. As a result, the discipline of microstructure under different technics condition was obtained, which establishes the foundation of DMD to control microstructure and then to control properties of metalwork.