A statistical analysis of the variation in measured crystal orientations obtained through electron backscatter diffraction

Electron backscatter diffraction (EBSD) techniques are used to determine the crystallography of individual metal grains. This paper examines the variability in the orientation of measurements obtained by EBSD. Although precision and statistics of orientation have been explored in the literature, little attention has been paid to formal statistical inference for quantifying variation in orientation measurements. Our intention is to study precision by developing statistical analyses for quantifying multiple sources of orientation variation, given repeat scans of a metal sample. Three sources of variability are simultaneously explored: variation in repeat measurements at a fixed location, variation among locations within a grain, and grain-to-grain variation. Bayes statistical methods will be applied to a hierarchical model with the uniform-axis-random-spin (UARS) components of Bingham et al. [1] to quantify these sources of variation. Repeat scans of a Inconel 600 specimen will be used to provide an illustrating example of how the statistical methods can be used to arrive at precision estimates.