Typical magnetization method for winding cable method
Magnetization method detection characteristics: the flexible cable is used to surround the workpiece and electromagnetically.
Application range: used to detect discontinuities parallel to the direction of current flow.
note:
1. For the longitudinal defects of the fillet weld of the tube sheet and the fillet weld of the tube seat, the cable method can be used.
2. Care should be taken to control the spacing between the weld and the cable.
3. Use standard test strips to verify that the magnetization specification meets the requirements.
Typical magnetization method of cross yoke method
Method of using a cross yoke
1. A magnetically magnetized workpiece must be used to apply a magnetic suspension while moving the yoke.
2. In order to ensure sensitivity and not cause missed detection, the moving speed of the yoke cannot be too fast and cannot exceed the standard value, that is, 4 m/min. It is considered that the moving speed of the yoke is too fast, and the influence on the surface crack is not hit, but for the near surface crack, even if the buried depth is only a few tenths of a millimeter, it is difficult to form a magnetic mark.
3. The spraying of magnetic suspension is essential, and it must be kept in a wet state within the effective magnetization field to facilitate the formation of defect magnetic marks. Especially for cracks with burial depth, due to improper spraying of the magnetic suspension, the formed defect magnetic marks are brushed off by the magnetic suspension, resulting in missed inspection.
4. Magnetic trace observation must be performed immediately after the yoke passes to avoid damage to the formed magnetic marks.
5. There is also an effective magnetization field on the outside of the cross yoke, which can be used to magnetize the workpiece, but the range of the effective magnetization field must be determined by the sensitivity test piece.
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