Influence of Quasi-Beta Heat Treatment on Acoustic Behaviors of Ultrasonic Inspection of TC4-DT Alloy

The microstructure and microtexture of TC4-DT alloy before and after quasi-β heat treatment are investigated, as well as the influence on the acoustic behaviors of ultrasonic inspection. C-scan ultrasonic images are obtained to investigate the evolution of microstructure confirmed by metallography and electron backscatter diffraction (EBSD) analysis. Noise level and signal-to-noise ratio (SNR) of ultrasonic inspection are also quantitatively verified. The results show that when TC4-DT alloy undergoes quasi-β heat treatment, attenuation and scattering of acoustic energy is significantly different. During this process, the scattering mechanism of acoustic changes from Rayleigh scattering to Phase scattering, which is mainly controlled by the grain size. Under the same scattering mechanism with the uniform average grain size, however, the regions of a-phase crystallites with a certain orientation contribute to the scattering of the acoustic wave. This finding is helpful for estimating ultrasonic inspection ability of large components.