The phantom wave of ultrasonic flaw detection is not a defect wave, nor a deformation wave, but a non-defect wave caused by comprehensive factors such as material and equipment. The generation of phantom wave is only due to the repetition frequency of the synchronization pulse in the synchronization circuit of the ultrasonic flaw detector. High, which determines the repetition frequency of the transmitted pulse, that is, the number of ultrasonic pulses transmitted to the workpiece to be inspected per unit time.
If the repetition frequency is high and the sensitivity adjusted during flaw detection is also high, the multiple reflection signals that have not been fully attenuated will fall into the next scanning cycle, resulting in phantom waves. The generation of phantom waves has a lot to do with the type of material. Since d≤λ (d is the diameter of the grain and λ is the wavelength), the scattering attenuation is proportional to the cube of the diameter of the grain. When the material has good sound transmittance, if it is scanned multiple times before the next unit scan starts, If the reflected echo has not yet attenuated, it is easy to produce phantom waves.