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Laser-Powder Bed Fusion (L-PBF) manufactured 316L stainless steel has a peculiar subgrain microstructure with cellular structures comprised of a network of dislocations and a nanophase dispersion of oxide inclusions in the as-built material. This microstructure provides enhanced mechanical properties and corrosion resistance. However, it also adds a significant amount of residual stresses and microstructural inhomogeneity, resulting in variability in material properties. Many studies have been performed to characterize the cellular structure, but none are focused on studying the evolution of the nanophase oxide dispersion and its effect on grain growth. \ A typical feature of the microstructure in L-PBF 316L stainless steel is a bimodal particle size distribution of inclusions, which has not been modelled yet for any material system. Secondly, coarsening of second-phase particles in grain growth simulations has not been considered yet. In this thesis, a computational framework supported by experimental data to predict the evolution of the average grain size is presented, considering the bimodal dispersion and coarsening of inclusions. The starting point for the simulations is assumed as a fully recrystallized equiaxed microstructure. \ The framework is thoroughly evaluated for 316L stainless steel. The recrystallization time for L-PBF 316L stainless at 1200 $^circ$C is determined as 1h. All the inclusions are identified using Scanning Electron microscopy and identified using EDS (energy dispersive X-ray spectroscopy). Rhodonite was found as a meta-stable phase present after recrystallization until 2 hours of heat treatment at 1200 $^circ$C. Further increasing the heat treatment temperature, Rhodonite was transforming to $SiO_2$. The particle size distribution and grain size are calculated and used as an initial condition for the grain growth simulations using the phase field method. No significant coarsening of particles and grain growth was observed. The understanding of the experimental observations is built with thermodynamic simulations, and grain size evolution is computed with phase field simulations. \ The existing framework is currently constrained by the limited resolution of nanophase oxides (0.1 $mu m$) and grains ((10 $mu m$)) within the same mesh, which subsequently limits the statistics required for grain growth simulations. Despite this limitation, the framework enables a comprehensive analysis of the material's grain growth phenomenon.