Ultrasonic attenuation measurement using backscattering technique

Ultrasonic backscattering measurements by means of spatial averaging technique were carried out in steel to determine the ultrasonic attenuation coefficient. The attenuation coefficients were evaluated from the exponential decay of the backscattering signal. The results were compared with those obtained by evaluating the amplitude decay of the main pulse. Good agreement is observed provided the condition is valid, i.e. Rayleigh scattering with d/lambda equal or smaller than 0.2 and or weak elastic anisotropy of the single crystal. Otherwise multiple scattering becomes dominant and the amplitude decay of the backscattering curve is no longer related to the attenuation coefficient.