Ultrasonic testing

Ultrasonic testing is used for the detection of material faults by ultrasound, i.e. with sound vibrations of over 20,000 Hz. The frequencies used lie between 0.05 MHz and 25 MHz. In practice, cast-part testing typically uses frequencies of 0.5 to 5 MHz. The coarser the grain structure, the lower the frequency must be chosen, because the grain boundaries scatter the sound and reduce penetration depth.