Post processing effects on GND calculations from EBSD-based orientation measurements

Electron Backscatter Diffraction (EBSD) has shown great utility in characterizing the aspects of microstructure related to crystallographic orientation. Such information is critical to understanding deformation in crystalline materials as well as the impact of deformation induced structural variations on recrystallization. Small angle rotations induced by the production of dislocations and their movement through the structure can be well captured by EBSD. Geometrically Necessary Dislocations (GND) can be derived from the measurement of these local variations in orientation. However, these local orientation variations are often right at the limit of angular precision that can be achieved by EBSD. Various post-processing tools have been developed to improve the angular precision. However, this is generally achieved through point-to-point smoothing of the orientation data within the measurement grid. The impact of such various filtering method are explored in terms of their impact on GND calculations. A new post processing approach which improves the EBSD indexing rate will also be presented along with results on its influence on local orientation variations. Fortunately, the general conclusion drawn from the reduction results is that these approaches generally improve the overall GND measurements.