Heterogeneous structures in a Ni-based superalloy with tailoring mechanical properties produced by a twin laser powder bed fusion system.

Powder bed fusion using a laser beam (PBF-LB) is a promising additive manufacturing (AM) technology, used to produce components with complex geometry and design freedom. The parts are built in a layer-by-layer fashion during PBF-LB, and changing the processing parameters within different layers can lead to the modification of microstructures and finally a great impact on the mechanical properties. Thus, PBF-LB provides the possibility for the customization of material properties by changing the microstructures of layers using different processing parameters. In this investigation, a twin PBF-LB system, i.e., with a low-power laser beam and a high-power laser beam in a machine, is used to produce fine and coarse microstructures using the Inconel 718 (IN718) alloy, respectively. The fine and coarse microstructures are alternately printed to form different heterogeneous structures. Correspondingly, different mechanical properties are achieved. The microstructures are analyzed using optical microscope (OM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and numerical calculation. The defects generated by these 2 laser beams are simultaneously discussed. This study facilitates the tailoring of alloy properties using the PBF-LB technology to meet the users' needs of multiple service conditions. • IN718 heterogeneous structures are built by PBF-LB using 2 different laser systems. • A fine microstructure is formed using the low-power laser beam. • The high-power laser beam tends to produce the samples with coarse grains. • The different sizes of microstructures are ascribed to the different cooling rates. • The heterogeneous structures have effects on the mechanical properties. [ABSTRACT FROM AUTHOR]