Surface integrity of nickel-based alloys subjected to severe plastic deformation by abusive drilling

Surface integrity of nickel-based superalloys after machining operations has become a topic of major interest in the aerospace sector. In the present work, the characteristics of nickel-based alloys (Alloy 718, Waspaloy, Alloy 720Li, and RR1000) subjected to abusive drilling conditions have been investigated using experimental methods such as FEG-SEM, EBSD, XRD, TEM and nano-indentation. The results indicated the presence of nano-sized grains typical of severe plastic deformation in the machined surface while the presence of plastic slip bands was observed in the sub-surface layers. Correlations between the thermo-mechanical properties of the nickel-based alloys and the severe plastic deformation features of the machined surfaces are presented.