Advantages and disadvantages of us 100 ultrasonic wave

Ultrasonic flaw detection has the advantages of large detection thickness, high sensitivity, high speed, low cost and no harm to human body, and can locate and quantify defects. Ultrasonic flaw detection shows that the defects are not intuitive, the flaw detection technology is difficult, and it is easily influenced by subjective and objective factors, so the flaw detection results are not easy to save. Ultrasonic flaw detection needs smooth working surface and experienced flaw detection personnel to distinguish the types of defects, which is suitable for flaw detection of parts with large thickness, so ultrasonic flaw detection also has its limitations.

The disadvantage is that there are many kinds of ultrasonic flaw detectors, but the pulse reflection ultrasonic flaw detector is the most widely used. Generally speaking, in homogeneous materials, the existence of defects will cause material discontinuity, which often leads to the inconsistency of acoustic impedance. From the reflection theorem, we know that ultrasonic waves will be reflected at the interface of two media with different acoustic impedances. The reflected energy is related to the acoustic impedance difference between the two sides of the interface and the orientation and size of the interface. The pulse reflection ultrasonic flaw detector is designed according to this principle.

Most pulse reflection ultrasonic flaw detectors are A-scan. The so-called A-scan display mode means that the abscissa of the display is the propagation time or distance of the ultrasonic wave in the detected substance, and the ordinate is the amplitude of the reflected ultrasonic wave. For example, there are defects in the workpiece. Due to defects, the interface between different media is formed between defects and materials. The acoustic impedance between interfaces is different. When the emitted ultrasonic wave meets this interface, it will be reflected, and the reflected energy will be received by the probe. The reflected wave shape will be displayed at a certain position on the abscissa of the display screen. This position of the abscissa is the depth of the defect wave in the detected material. The height and shape of this reflected wave vary with different defects, reflecting the nature of defects.