Ultrasonic flaw detector common detection method

Ultrasonic flaw detector is a non-destructive testing instrument, which has the characteristics of rapid, convenient, non-damage, precise positioning, etc. It is widely used in boilers, pressure vessels, aerospace, aviation, power, petroleum, chemical and Other industries, mainly in the following detection method:

1. The pulse reflection method The ultrasonic probe transmits the pulse wave to the test piece. The method of detecting the defect of the test piece according to the condition of the reflected wave is called the pulse reflection method. The pulse reflection method includes defect echo method, bottom wave height method and repeated bottom wave method.

2. Penetration method Penetration method is a method of judging the defect condition based on the energy quality change after pulse wave or continuous wave penetration of the test piece. Penetration method often uses two probes, one for one, placed on both sides of the specimen to detect.

3. Resonance method If the sound wave (frequency-adjustable continuous wave) propagates within the object to be inspected, when the thickness of the test piece is an integral multiple of the half wavelength of the ultrasonic wave, resonance will occur, and the instrument will show resonance frequency. When there is a defect in the test piece or a change in the thickness of the work piece, the resonance frequency of the test piece will be changed. The method of judging the defect condition and the variation of the workpiece thickness according to the resonance frequency characteristic of the specimen is called a resonance method. Resonance method is commonly used in test thickness measurement, forging and casting ultrasonic flaw detector flaw detection principle.

There are multiple wave types when ultrasonic waves propagate in the medium. The most commonly used inspections are longitudinal waves, transverse waves, surface waves, and slab waves. Use longitudinal waves to detect defects such as inclusions, cracks, shrinkage tubes, white spots, and delaminations in metal ingots, billets, plates, large forgings, and articles with relatively simple shapes; shear waves can be used in pipes to detect Peripheral and axial cracks, scratches, porosity in welds, slag inclusions, cracks, incomplete penetrations, etc. Surface flaws on parts that can be detected with simple surface waves; Plates can be used to detect thin sheets defect.