This work examines the effects of various heat treatments on the microstructural characteristics and corrosion resistance of 316L stainless steel fabricated by L-PBF. The microstructural evolution and corrosion properties at different heat treatment temperatures (500°C, 750°C, and 1000°C) were assessed by utilizing electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and electrochemical polarization tests. It has been found that increasing heat treatment temperature significantly alters the grain size, reduces dislocation density, and impacts corrosion resistance of the material. The melt pool boundaries, visible in the as-fabricated samples, begin to fade at 750°C. Corrosion tests demonstrate a decrease in pitting and repassivation potentials with increased heat treatment temperature, suggesting a deterioration in the material's resistance to pitting corrosion. The study highlights the complex relationship between heat treatment conditions, microstructural evolution, and corrosion resistance in 316L stainless steel, deepening understanding of processing-structure-property relationships in additively manufactured metals used in corrosive environments.