Effect of printing parameters on microstructure development of LPBF manufactured Inconel 718 alloy

Laser powder bed fusion (LPBF) is an advanced manufacturing technology, which is increasingly used in various industries for building highly complex engineering components. Hereby, processing parameters of LPBF can lead to several types of printing defects and thus altered mechanical properties of printed alloys. In order to achieve high performance of LPBF parts, not only an avoidance of manufacturing defects, but also better understanding of effects of processing parameters on microstructure developments is currently challenging. In this work, it was thus aimed to study the influences of energy density on the occurred microstructure characteristics including Lave phase, primary dendrite and internal residual stress of printed Inconel alloy produced by LPBF. Hereby, IN718 samples were fabricated using the power of 80, 105, and 125 W with a constant scanning speed of 400 mm/s. These used printing parameters led to varying cooling rates of build samples and could thus strongly affect the microstructure development. Then, microstructure features of the build specimens such as size, fraction of the Lave phase, primary dendrite arm spacing as well as residual stress were determined by SEM and XRD analyses. Finally, the results were correlated and discussed with obtained tensile properties and printing conditions.