Ultrasonic detection of transverse crack

Transverse crack has great harm, compared with other defects, it is more difficult to detect, easy to miss, which is the key is the identification of defect properties in ultrasonic inspection.This paper summarizes the method of ultrasonic detection of transverse crack by type A pulsed reflection method, as follows:

1. When ultrasonic detection is used for parallel scanning of welding seam with residual height, it is difficult to find transverse cracks. This is because of the existence of residual height of welding seam and the position of transverse cracks.In daily inspection, in order to ensure the effective detection of transverse cracks in important welds, all the residual heights of welds are generally polished and leveled, so as to ensure that the probe can conduct parallel scanning on the welds, so as to improve the detection rate of transverse defects.

2. oblique parallel scanning with high welding seam in order to effectively detect the transverse cracks of high welding seam, the probe can be arranged on both sides of the edge of the welding joint, and the probe and the center line of the welding joint into 10 degrees 20 degrees, oblique parallel scanning in two directions.

3. After removing the weld residual height, parallel scanning will grind the weld residual height flat, and detection on the weld is the most effective method to check the transverse crack.  When testing, the probe is placed on the weld and the heat-affected zone to conduct parallel scanning in two directions.

4. A probe is placed on both sides of the weld for the cross scan of the double probe across the weld. The measured value of K of the two probes is generally required to be the same, so as to ensure that the incident acoustic beam can be received by the receiving probe to the maximum extent after the reflection of the defect, and it is easy to locate.When detecting, it is necessary to ensure that the axes of the sound beam of the two probes intersect at the part to be detected, and the two probes are moved in the same direction parallel to the center line of the weld on both sides of the weld at the same time, so that the transverse defects of the weld can be detected. This scanning method is called cross scanning.