ULTRASONIC AND NEUTRON-DIFFRACTION CHARACTERIZATION OF TEXTURE IN AN INHOMOGENEOUSLY ROLLED TITANIUM PLATE

Deviations from orthotropic symmetry have been reported (R. B. Thompso n, J.F. Smith and S. S. Lee, J. Acoust. Soc. Am., 80(1986)921) in the angular variation of the apparent velocities of ultrasonic guided mode s propagating in a rolled titanium sheet. Additional ultrasonic and ne utron diffraction measurements are presented which reveal those result s to be a consequence of a subtle textural inhomogeneity, apparently d eveloped as a result of non-uniform rolling across the sheet width. Ul trasonic and neutron diffraction measurements in material representati ve of the two sides of the sheet are reported which quantify the diffe rences in the structure of the two sides. A theory is then presented w hich predicts the apparent angular dependence of the ultrasonic veloci ty in such a sheet, modeled as two adjacent homogeneous regions with s lightly different properties. When the texture parameters in that theo ry are set equal to the values deduced from the neutron diffraction me asurements, good agreement with the observed apparent velocities is ob tained. These results illustrate the importance of sample homogeneity in ultrasonic texture analysis and the high sensitivity of the ultraso nic technique to small changes in texture.