Shermann Min
Lawrence Peng
Wei-yang Lu
Darcy Hughes
Sandia Natl. Labs., Livermore, CA 94551
Metal forming operations such as deep drawing, stretching, bending, hemming, etc. are all significantly influenced by the degree of crystallographic anisotropy (texture) present within the workpiece. An effort is underway at Sandia National Laboratories/CA to develop two noncontact ultrasonic systems for the measurement of texture in aluminum sheets. Although the effect of stress wave velocities on elastic anisotropy is well known, its ability to predict plastic behavior has yet to be firmly established. Ultrasonic measurements, which hold the potential for remote, in-process screening, will be shown to exhibit a high degree of correlation with current techniques for measuring texture, which are off-line, destructive, and often inaccurate. Results from an electromagnetic acoustic transducer (EMAT) system are used as a baseline comparison for a more promising noncontact technique involving the optical generation and detection of ultrasound, commonly referred to as laser ultrasonics (LU). In addition to displaying the level of anisotropy, slowness curves obtained from these systems suggest the ability to distinguish between different types of texture, as predicted from theory.