Ultrasonic characterization of effective elastic constants and texture in aluminium correlated with EBSD

Abstract

Electron Backscatter Diffraction (EBSD) is a microscopic technique that provides detailed crystallographic orientation information for given samples. It enables the quantitative calculation and visualization of important microstructural properties such as grain size, aspect ratio and the average grain orientation of the aggregate, commonly known as the Orientation Distribution Function (ODF). In order to validate an ultrasonic technique to quantitatively describe texture we are correlating ultrasonic velocity measurements with results from EBSD. The velocity variations as a function of angle from the Rolling Direction in sheet samples are dependent on such quantities measurable by the EBSD technique. We describe here a modified technique to extrapolate the three independent Orientation Distribution Coefficients (ODCs) W-400, W-420 and W-440 for cubic structures from the Bunge-Euler angle data determined through EBSD scans as a description of texture within the sample. EBSD results, taken from through-thickness scans to eliminate the errors that arise with surface-to-bulk inhomogeneity, for rolled aluminium sheets are discussed and compared to the ODCs obtained using an ultrasonic EMAT-EMAT S-0 Lamb wave velocity measurement system