A comparative study of porosity rate measurement methods and influence of energy density in Inconel 718 produced by laser powder bed fusion additive manufacturing process

Components produced by direct metal laser sintering routinely contain porosities. This work aims to examine the various kinds of pores produced by laser powder bed fusion and compares various techniques for determining part density for the components manufactured using optimum parameters with various volumetric energy densities for Inconel 718 nickel-based superalloy. The porosity rate was quantified using three different techniques: Helium pycnometer, Archimedes method and micrographic observation. When comparing these techniques, it was found that the Archimedes method and the helium pycnometer technique produced comparable results, while the micrographic observations consistently underestimated the porosity rate. The relationship between porosity and mechanical properties is evaluated. The laser powder bed fusion additively manufactured Inconel 718 samples were able to attain high levels of densification, approximately 99.28% while maintaining a low porosity rate of around 0.47% and exhibited notable mechanical strength, including an ultimate tensile strength of 1246.984 MPa.