Additive manufacturing techniques have revolutionized the manufacturing processes across various applications that require complex or custom geometries/applications. However, the AM part's surface finish and dimensional accuracy are usually not optimal. Hence, to improve these, post-processing techniques like micro-turning are necessary. The subsequent operation induces temperature during machining, which causes changes in the microstructural properties of the material and therefore affects the mechanical properties of the workpiece. The main metal components of aircraft structures and engine components are nickel-based alloys due to their resistance to heat, corrosion, thermal fatigue, creep, and erosion. When these important structural components are manufactured in the aerospace industry to achieve high-reliability levels, surface integrity is one of the most relevant parameters used to evaluate the quality of finished surfaces. In this study, through simulation, we compared the cutting temperatures produced during the machining of Forged as well as L-PBF Inconel 718 (IN718). The Johnson–Cook (JC) model along with JC damage parameters are used to develop a thermal-based modeling approach that takes into account surface and machining conditions that cause heat generation at the tool-workpiece interface. The impact of the simulation of the orthogonal cutting process is implemented in a finite element method (FEM) model–based commercial software, ABAQUS-explicit. We could observe an increase of about 10% in cutting temperature during the machining of L-PBF IN718 compared to the forged IN718. This could be due to the change in mechanical properties and the rough nature of the surface produced through the L-PBF process. Additionally, subsurface cutting temperatures have also been calculated for the materials.