Influence of different beam shapes on melt pool geometry of single melt tracks on IN718

The application of beam shaping is gaining more attention in additive technologies like Powder Bed Fusion of Metals using a laser-based system (PBF-LB/M). The paper at hand gives an insight in the application of three different laser beam shapes (a state-of-the-art Gaussian beam profile, a ring-core distribution 80/20, and an inversely calculated beam shape, based on a homogeneous melt pool temperature distribution in the conduction welding mode) producing single melt tracks on bare IN718 plates without powder. Executed investigations show a distinct difference concerning the generated melt pool dimensions, process windows, as well as solidification orientation. With the application of beam shaping, the avoidance of the keyhole mode with a more homogeneous temperature distribution in the melt pool delivers wider melt tracks, less process faults like balling, deep penetration of the laser (keyholing), protrusion and depression of the solidified melt pool, as well as a convenient process window with respect to part quality and process speed. The melt pool can be enlarged to a width of about 800 µm without any detectable process faults and a very flat penetration with the usage of beam diameters of 750–790 µm.