Unsupervised approval criteria for automated EBSP investigation of deformed metals

Unsupervised approval criteria have been investigated for orientations gath ered from cold deformed samples (medium to high strain range) using the ele ctron backscattering pattern technique. For such samples, the dislocation c ell-size is on the order of the available step-size and pattern quality is generally low. Approval criteria for assessing the validity of measured ori entations under these conditions were determined using, as a calibration, c hannel die cold deformed single crystals of stable orientations. In all cas es, approval criteria based on an indexing confidence measure are found to be preferable. Different criteria are suggested, depending on whether the o rientation data are subsequently to be used for texture analysis, or for a misorientation angle-based analysis. The latter is illustrated by an invest igation of the number of deformation generated high angle boundaries introd uced during a 90% cold reduction of a polycrystalline sample.