Induced porosity in Super Alloy 718 through the laser additive manufacturing process: Microstructure and mechanical properties

This paper addresses characterization of Super Alloy (Inconel) 718 manufactured through the powder bed fusion (PBF) process. Specimens were fabricated using five different sets of process parameters to induce a range of porosities within the samples. Scanning electron microscopy and micro-computed tomography methods were used to characterize microstructures of these specimens, and mechanical properties were measured using tension, compression, and impact tests. Energy absorption proved to be highly sensitive to density, and stress-strain curves from compression testing were found to behave much like open-cell foams in the presence of high porosity. The similarities with open-cell foams were confirmed with scanning electron microscopy images. Micro-computed tomography scans indicated that the induced porosity was continuous throughout the specimens. - Highlights: • Inconel 718 manufactured through the powder bed fusion process is characterized. • Laser power, scan speeds and hatch spacings are varied to give various densities. • Microstructure is characterized by SEM and micro-CT. • Mechanical properties are measured by tension, compression and impact tests. • Mechanical properties drop significantly with increased porosity.