Quantitative determination of the defects in TC4 diffusion bonded joints via ultrasonic C-scan

Ultrasonic C-scan was conducted to detect the defect size of TC4 diffusion-bonded joints quantitatively. Additionally, C-scan images were obtained using the amplitudes of time-domain signal, main frequency of frequency-domain signal, and amplitudes of main frequency in power spectrum as the characteristic parameters. The results demonstrated that the C-scan detection based on the time-domain amplitude was feasible to characterize the defects with sizes larger than double the focal spot diameter of the probe accurately and quantitatively. When the defect size was larger than the focal spot diameter, the detection error of using the main frequency of frequency-domain signal was below 5%. For defects smaller than the diameter of the focal spot, the highest detection accuracy was obtained by ultrasonic C-scan based on the power spectrum.