Influence of energy density on macro/micro structures and mechanical properties of as-deposited Inconel 718 parts fabricated by laser engineered net shaping

In the present study, the influence of laser energy density (LED) on geometrical characteristics, mechanical properties and microstructure of Inconel 718 parts fabricated by laser engineered net shaping (LENS) were investigated. Thin walls and block specimens were designed and fabricated under a total of 25 different energy density combinations. The material properties, including part dimensional shrinkage, surface roughness, surface hardness, and microstructures, including, porosity, geometrical dilution, average grain size and dendrite arm spacing (DAS), were evaluated. The results of this investigations indicate that with the increase of LED, the part shrinkage and surface roughness present a down and up trend, whereas the porosity, geometrical dilution, grain size and DAS increase with increasing of LED and there is no statistically significant effect of LED on the surface micro hardness. Taking account of the material characterization results, the energy density window for LENS process of Inconel 718 is suggested between 98.21 J/mm2 to 107.14 J/mm2. The outputs of this study could provide an insightful view of the effects of energy input on mechanical and microstructural properties of as-deposited Inconel 718 alloy by LENS process.