This work investigates the impact of varying powder layer thickness on the microstructure and mechanical properties of Inconel 718 specimens fabricated through Laser-Powder Bed Fusion (L-PBF). The research aims at examining the microstructure development along YZ as well as XY planes (Z being the building direction) and evaluating tensile strength, microhardness, relative density, porosity, and dry sliding wear behavior of the as built part. The micrographs exhibit direction-dependent columnar/cellular dendritic grain morphology dominated by the local thermal gradient. As compared to the conventional wrought alloy, the as built L-PBFed Inconel 718 part exhibits a very fine microstructure influenced by the high rate of undercooling. The thicker powder layer leads to greater elongation (∼ 1.08% increase in fracture strain) while the thinner layer demonstrates superior strength; the increment in the average Ultimate Tensile Strength (UTS) is 140.64 MPa. All test specimens approach nearly full density; obtained relative density varies from 98.14% to 99.9%. An increase in layer thickness causes an increased degree of porosity. The decrement (∼73.6 HV10) in the Vickers microhardness value is experienced at higher layer thickness. During the dry sliding wear test at room temperature, the part fabricated with a thinner layer is associated with a lower coefficient of friction. The as built fine microstructural morphology disappears after Homogenization Treatment (HT) followed by double-stage Aging Treatment (AT). AT promotes precipitation strengthening thus the post-heat treated specimens show improved microhardness.
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