Today, advances in precision machining allow the fabrication of structures with sizes of a few microme-ters. As this is within the typical grain size distribution of crystalline materials, the tool is often engaged with single grains. Therefore the effects of microstructure, like grain size and crystal orientation become critical. Anisotropy effects could be useful to facilitate machining processes, in particular by dictating the formation of chips and their discontinuity when a grain boundary is crossed.
This motivated our interest to investigate the deformation mechanisms as a function of grain orienta-tion by means of in-situ microscratching experiments in combination with electron back scattered diffraction technique (EBSD). Through this study it could be shown that crystal orientation affects the de-formation behavior, as activated slip systems change their orientation with respect to the sample surface and plastic deformation is propagating into different directions. Thus, it is possible to improve the micro-machinability of crystalline materials if the crystal orientation is known with respect to the machining direction so that preferred directions favoring chip formation over pile-up could be selected, resulting in better surface finish and lower forces during the cutting process. For textured materials, this finding might be even applicable on a larger scale.
Contact: Johann Michler