The use of ultrasonic testing methods is to detect instrument called the ultrasonic flaw detector. Its principle is: the ultrasonic wave propagation in the material is detected, the acoustic properties of the material and the internal organization changes have some impact on the propagation of ultrasound technology affected the extent and condition of the ultrasonic probe understanding of material properties and structural changes called ultrasonic detected. Ultrasonic testing methods usually penetration method, the pulse reflection method, serial method. Penetrating ability, probing depth up to several meters.

The x-rays can penetrate the general visible light impervious material. The strength of its ability to penetrate, with the x-ray wavelength, and be penetrated to the density and thickness of the substance concerned. x-ray wavelength, lower the density, the thickness of the thinner, the x-ray as easy to penetrate. In the actual work by the size of the tube voltage V values ​​(kV) to an x-ray to determine the penetration (i.e. the quality of the x-ray), and the unit time (mA) and the product of the time of the current through the x-ray represents the amount of x-ray. The maximum thickness can be measured and related to the x-ray intensity, general metal thickness is less than 0.3 meters.

Compared with X-ray detection, ultrasonic flaw detection has some advantages: higher detection sensitivity, short cycle, low cost, flexible and convenient, high efficiency, harmless to the human body;

Compared with X-ray detection, ultrasonic flaw detection has some shortcomings: work surface smooth, requires the inspection of experienced personnel in order to identify the types of defects, defect is not intuitive.