Residual strain orientation in rolled titanium determined with synchrotron X-ray Laue microdiffraction

Abstract

Previously, synchrotron X-ray Laue microdiffraction has been used to measure the magnitudes of residual strain in materials. Recently the method was advanced to determine the orientation of the strain ellipsoid and applied to naturally deformed quartzites; however, the deformation history of these quartzites is ambiguous due to their natural origin. In this study, synchrotron X-ray Laue microdiffraction (µXRD) is used to measure the residual strain for the first time in a sample with known stress history, rolled titanium. A deviatoric strain tensor is calculated from each Laue diffraction image collected with two µXRD scans of a rolled titanium sheet in different sample orientations. The principal strain axes are calculated using an eigen decomposition of the deviatoric strain tensors. The results show that the principal axis of compression is aligned with the normal direction of the titanium sheet, and the principal axis of extension is aligned with the rolling direction. Pole figures are used to represent the 3D distribution of residual strain axes.

The Problem of Observing the Maximum of a Superposition Wave Field

“…Introduction. Despite the long-standing solution, the problem of describing a diffracted flat field on an ideal periodic structure in the far observation zone, the results of Laue [1] remain relevant to this day [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. As it is known, the Laue conditions correspond to the kinematic picture of diffraction, when in the crystal volume the re-emitted field is considered to be significantly smaller than the primary field, which, as a rule, is considered in the form of a plane wave.…”