Ultrasonic Attenuation as Influenced by Elongated Grains

Abstract

Reliable nondestructive evaluation of structural/machine components fabricated from polycrystalline materials require the knowledge of attenuation and dispersion of an ultrasonic wave propagating through such microscopically inhomogeneous medium. Expected propagation characteristics of ultrasonic waves in randomly oriented equiaxed grains are relatively well understood. But when the grains are elongated and/or preferentially oriented, the wave propagation constants exhibit anisotropic behavior. The authors have published a number of research articles on propagation of ultrasonic waves in materials with macroscopic texture and elongated grains. The present paper sheds more light on the effect of grain shape on the attenuation and dispersion of ultrasonic waves in polycrystals. Specifically, theoretical results are presented showing the effects of different grain aspect ratios. It is observed that for the same effective grain volume, grain elongation has smaller effect on attenuation.