Analysis of tool wear and cutting characteristics in milling of powder metallurgy nickel-based superalloy by various coatings

Nickel-based superalloys are essential materials for turbine engine components in aerospace applications. However, it is difficult to manufacture nickel-based superalloys with high surface integrity due to the high cutting forces, high cutting temperatures, and severe work hardening, which usually requires cutting tools with good thermal conductivity, superior high-temperature performance, and high abrasion resistance. This paper investigates the tool wear mechanism and machined surface integrity of the refractory powder metallurgy nickelbased superalloy FGH 4097 during milling at different speeds, with a special focus on the effect of various coatings (TiAlCrN, TiAlN, and TiAlSiN). The relationship between tool flank wear (VB) and material removal volume (MRV) was studied, and the cutting force signals were analyzed in both the time and frequency domains. This work also examined the influence of tool wear with various coatings on both the surface morphology of machined parts and the distribution of residual stress. Furthermore, the mechanisms of tool wear for different coatings were revealed by analysis using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results demonstrated that the wear characteristics on the three coated tools were similar during milling at a lower speed. However, the TiAlCrN coated tool demonstrated superior performance at high cutting speed. For the identical coated tools, the cutting force and roughness of the surface increased with the elevation of cutting speed when holding an identical amount of MRV. The SEM and EDS analysis revealed that adhesive wear was found to be the dominant mechanism of tool wear for the tested tools, regardless of the coatings used, while the TiAlN-coated tool also exhibited abrasive wear.