High-dynamic self-shielding pulsed eddy current detection probe and defect detection method

Abstract

The invention discloses a high-dynamic self-shielding pulsed eddy current detection probe and a defect detection method. The probe comprises an external disc-type excitation coil, an internal basin-covered active self-shielding coil, a high-precision magnetic field sensor and an annular magnetic field gradient sensor array, the disc-type excitation coil and the basin-covered active self-shielding coil are coaxially arranged and are connected in series with an external power supply in a reverse direction, and the internal current is equal in size and reverse in the working process; the disc type excitation coil and the basin covering type active self-shielding coil generate a large-range forward incident magnetic field and a local reverse shielding magnetic field below the probe; the high-precision magnetic field sensor is located at the axis of the bottom of the probe, incident magnetic fields at the axis are mutually counteracted, and the magnetic field sensor only picks up a vertical component of an eddy magnetic field in a measured body; the annular magnetic field gradient sensor array is located between the exciting coil and the disc type coil at the bottom of the probe and picks up magnetic field gradient signals, the probe shields invalid coil magnetic fields in pulsed eddy current detection signals, distribution of incident magnetic fields in a detected body is balanced, and high-precision pulsed eddy current detection is achieved.

Description

technical field [0001] The invention belongs to the technical field of nondestructive testing, and in particular relates to a high dynamic self-shielding pulsed eddy current testing probe and a defect testing method for detecting metal component defects. Background technique [0002] In pulsed eddy current testing, the defect response is concentrated in the rising section of the detection signal, and the detection signal gradually tends to be consistent before the pulse excitation is turned off. Therefore, it is often necessary to extract the defect response characteristics of the rising section of the detection signal through differential processing. In the traditional scheme, since the magnetic field sensor picks up the information of the coil magnetic field and the eddy current magnetic field at the same time, there are a large number of invalid components in the detection signal, and the amplitude of the differential signal obtained by differential processing is much smal...

AI Technical Summary

Problems solved by technology

[0003] Due to the distribution characteristics of the incident magnetic field of the excitation coil gradually attenuating with the depth of the object under test, in pulsed eddy current testing, the response of the surface defects of metal components is often much larger than that of internal deep defects, so that internal deep defects are easily covered by surface defects, and there are major security risks. Hidden danger

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