Nondestructive Evaluation of Creep Damage Using Leaky Surface Acoustic Wave Technique

Creep has been one of the most concerned matters on high temperature components of thermal power plants, petrochemical plants, oil refineries and so on. In present study, leaky surface acoustic wave (LSAW) has been applied to detect and evaluate the creep. LSAW signals with broad-band frequency generated by large-aperture-angle line-focus transducer were analyzed. The feature parameters of LSAW pulse both in time domain and in frequency domain such as amplitude of signal and ultrasonic power spectrum vary with creep process. Particularly high frequency components of LSAW attenuate through the mechanism of sound wave scattering by creep voids and cavities. Consequently ultrasonic spectroscopy technique can be expected to be available for deducing the state of deterioration in material quantitatively on the basis of correlation between microstructure in long-term operation at high temperature and ultrasonic propagation characteristics theoretically and practically.