Ultrasonic texture measurement of sheet metals: an integrated system combining Lamb and shear wave techniques

We present a comparison of two techniques for the ultrasonic evaluation of the crystallographic texture of sheet metals: the use of polarised shear waves through thickness mode and the use of Lamb waves in a pitch-catch velocity vs angle in plane scan. Each technique is effective over a different range of thicknesses, with overlap in the millimetre regime. A direct comparison of the two techniques leads to a better understanding of the errors involved and approximations used. Additionally, we investigate the possibility of combining the two techniques into an integrated system capable of measuring the texture using both techniques almost simultaneously with little increase in complexity over either single system. This allows the determination of additional material parameters such as the thickness or averaged Lamé constants. Initial results show a generally good agreement between techniques for W 420 but a significant difference between results for W 400 which is attributed to variation in the materials constants.