Tailored ability of the microstructure and microhardness for nickel-based superalloy fabricated by LPBF

LPBF is widely used in the manufacture of nickel-based superalloy parts in aerospace industry. The microstructure which determines mechanical properties of parts is dependent on LPBF process parameters. In this work, the tailored ability of the microstructure and microhardness for LPBF built IN738LC were studied by altering heat input. The results show that the IN738LC alloy has a good printability and no crack or hole defects in the VED range of 40 J/mm³ to 97 J/mm³. The grain size increased with the heat input from a 100-micron scale of 44 J/mm³ to a millimeter scale of 94 J/mm³. The microhardness of xz plane is slightly higher than that of xy plane. Moreover, microhardness was increased from 340 HV_1.0 to 440 HV_1.0 and from 310 HV_1.0 to 420 HV_1.0 for xz plane and xy plane with increase of VED from 38 J/mm³ to 91 J/mm³.