In powder bed fusion of metals using a laser beam (PBF-LB/M), an industrially highly relevant additive manufacturing (AM) technology, process parameters such as the laser power can be locally modified. This allows for a tailoring of the mechanical properties or a modification of the cracking susceptibility of the manufactured parts. This can be reasoned by the resulting microstructure, which in turn is strongly dependent on grain-initiating nucleation phenomena [1]. Predicting these nucleation locations by means of numerical process simulations is, therefore, of high importance to widen the application area of PBF-LB/M. However, currently available nucleation models are either not able to represent the actually present nucleation rates in PBF-LB/M or need to be calibrated for each process parameter set, which impedes a first-time-right AM. The goal of this study was to extend classical nucleation models, which have proven to be promising approaches for PBF-LB/M microstructure simulations [2]. In this turn, the following working hypothesis was to be proven: Classical nucleation theories are capable of considering changes in the nucleation due to geometrically influencing factors, but only insufficiently for process parameter variations. For this, Inconel 718 cubes were experimentally manufactured using different laser powers, and the nucleation rate was determined as a function of the process parameter variation. The resulting regression model served as an input to the classical nucleation theories. Following the investigations of [3, 4], parts expected to exhibit a geometry-related heat accumulation were simulated by means of a calibrated moving heat source with varying laser powers, utilizing the finite element method. The grain nucleation locations based on the extended nucleation models were extracted and compared to the experimental results, replicating the simulation. The first results indicated a consistency of the hypothesis with the experimental and simulative observations. These investigations may contribute to a first-time-right manufacturing considering tailored microstructures in PBF-LB/M.