Transmission Kikuchi Diffraction study of texture and orientation development in nanostructured hard turning layers

Hybrid structure of white layer in high carbon steel – Formation mechanism and its properties

“…It is conceivable that the heat generated by severe plastic deformation results in localized areas reaching the phase transition temperature and that new austenite grains can form indeed. Further evidence that the severe plastic deformation resulted in a significant increase in temperature is to be found in the observation that certain martensitic regions have been observed that contained very low dislocation densities, pointing to such an increase in temperature that partial recrystallization of the martensite occurred, in line with earlier suggestions 22 .…”

“…Transmission Kikuchi diffraction enabled automated orientation analyses of nanostructured materials to be conducted in the SEM on a TEM sample 22 . The thickness of the TEM sample plays a vital role in determining the quality of the diffraction patterns and it is therefore important to note that these TKD scans were conducted on the TEM foil with a sample thickness of ~70nm.…”

Destructive and non-destructive testing methods for characterization and detection of machining-induced white layer: A review paper

“…EBSD analysis of the white layer in several nickel superalloys also revealed a fine equiaxed grain structure that is indistinguishable under optical light microscopy (M'Saoubi et al, 2014). Transmission EBSD has been used to show that the white layer formed when turning steels at high cutting speeds (Bedekar et al, 2015) and when broaching nickel superalloys (Chen et al, 2017), has a strong recrystallized texture. This contrasts with the shear texture seen for lower cutting speeds in steels.…”

“…In the machining of steel alloys, the temperature of the workpiece at the contact point can raise as high as the austenitic phase transformation limit (Barry and Byrne, 2002). XRD studies (Chou and Evans, 1999, Barry and Byrne, 2002, Hosseini et al, 2012b, Bedekar et al, 2015 have shown that austenitic transformation of the machined surface at high temperature followed by rapid cooling results in a higher retained austenite concentration. The resulting ultra-fine grained microstructure in this instance is a white layer.…”