Powder Bed Fusion of Metals using a Laser Beam (PBF-LB/M) has proven to be a competitive manufacturing method to produce customized parts with high complexity. A unique characteristic of this technology is the possibility to locally control the mechanical properties within a single part by tailoring the microstructural features. For this targeted adjustment, the grain structure itself has to be reliably predicted at first. In the course of the present studies, various nucleation theories were applied to the PBF-LB/M process and their suitability was evaluated. For this purpose, the two Sc-modified aluminum alloys Scalmalloy® and Scancromal® were processed with a novel experimental PBF-LB/M setup. The latter allows for a processing of small powder batches and an easy subsequent metallographic investigation. By performing melt pool simulations based on the Finite Element Method, the necessary input data for the nucleation models and the subsequent 2D microstructure simulation were obtained. The simulatively predicted microstructure based on the different nucleation theories were compared to real metallographic images and to results from the literature. Based on this comparison, an application recommendation of the implemented nucleation models was made for the PBF-LB/M process. By means of the obtained results, the predictive capability of microstructure simulations can be enhanced. Using the demonstrated approach, further grain nucleation models can be assessed for various additive manufacturing processes.