Finite element modeling of microstructural changes in Waspaloy dry machining

It has been well documented in the literature the importance of strict surface integrity checks upon performance and quality of machined components, especially for the safety critical components (e.g., aerospace) that work at cyclic high mechanical loads and elevated temperatures. In this field, Waspaloy, within the commercially available nickel-based superalloys, is extensively applied in different industries such as aircraft, chemical plant equipment, and petrochemical equipment. The main objective of this paper is to implement a reliable FE model, for dry orthogonal machining of Waspaloy, capable to predict microstructural changes and dynamic recrystallization during the cutting process. A user subroutine was implemented in FE code to simulate the dynamic recrystallization and consequently grain refinement and hardness variation on the machined surface and below it. Zener–Hollomon (Z-H) and Hall–Petch (H-P) equations were employed to, respectively, predict grain size and microhardness. In addition, depth of the affected layer was controlled using the critical strain equation. FE numerical model was properly calibrated using an iterative procedure based on the comparison between simulated and experimental results. Finally, very good agreement was found between experimental and simulated results of grain size, microhardness, depth of the affected layer, and other fundamental variables such as cutting forces, temperature, and chip morphology.