Selective Laser Melting (SLM) is an advanced additive manufacturing (AM) technique that utilizes a high-quality laser as an energy source to selectively fuse metallic powder and create three-dimensional components. SLM involves the use of a laser beam that scans the powder bed layer by layer in a controlled pattern, causing localized melting and solidification of the material to produce intricate and near-shaped parts. The microstructure, texture, and mechanical properties of components manufactured through SLM exhibit notable distinctions from those created through conventional processes mainly due to the rapid solidification rates and high thermal gradients that accompany the SLM process. The aim of this investigation is to comprehend the basics of microstructure development during solidification in SLM by means of computer simulations. To address the computational challenges posed by the complex events occurring during solidification, a parallelized 3-dimensional cellular automaton model (CA) has been implemented. The parallelization strategy employed in this work has allowed for a cell size as small as 0.80 micrometer to be used. Furthermore, the physical dimensions of the simulations are not limited by memory as such the model allows for macroscopic simulations of microstructure evolution. This has the advantage to facilitate the linkage with CPFEM or FEM models for the determination of the mechanical properties. Additionally, the implemented cellular automaton model considers the possibility of porosity formation resulting from insufficient melting and excessive energy density during the SLM process.