Pulse eddy electromagnetism nondestructive detection method based on probe with iron core coil

An iron core coil and pulsed eddy current technology, which is applied in electromagnetic measurement devices, electromagnetic/magnetic thickness measurement, material magnetic variables, etc. The effect of fast decay, short diffusion time, and enhanced detection capability

CN104155361AActive Publication Date: 2014-11-19BEIHANG UNIV
7 Cites 19 Cited by

Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2014-11-19

Smart Images

  • Figure 1
    Figure 1
  • Figure 2
    Figure 2
  • Figure 3
    Figure 3
Patent Text Reader

Abstract

The invention discloses a pulse eddy electromagnetism nondestructive detection method based on a probe with an iron core coil. The probe consists of an iron core bundle, an excitation coil and a detection coil, wherein the iron core bundle is arranged in the center of the excitation coil; the detection coil is arranged outside the excitation coil. When the probe with the iron core coil is adopted to perform pulse eddy detection on a part, a strong pulse magnetic field of a dense space can be generated, an excitation magnetic field is increased, the signal to noise ratio of a signal is increased, and pulse eddy detection on a component with a relatively large wall thickness can be achieved under a relatively high lift-off condition. When a pulse eddy electromagnetism nondestructive detection system based on the probe with the iron core coil is adopted for detection, the influence of the pulse eddy field inside the iron core to the detection signal can be measured according to a probe time constant tau s. When tau s is greatly smaller than a part diffusion time constant tau e, the influence of the pulse eddy field inside the iron core to the detection signal can be ignored, the function of the probe with the iron core coil can be approximated to be linear amplification of the detection signal, and thus the signal processing difficulty is reduced.
Need to check novelty before this filing date? Find Prior Art

Description

Technical field

[0001] The present invention relates to the field of electromagnetic nondestructive testing, in particular to a pulsed eddy current electromagnetic nondestructive testing probe capable of generating a pulsed strong magnetic field, and a pulsed eddy current electromagnetic nondestructive testing method based on the probe with an iron core coil. Background technique

[0002] In the petroleum, chemical, electric power, metallurgy and other industrial fields, metal pipes and pressure vessels are widely used to transport and store liquid or gaseous media. Most of the conveyed media have the characteristics of high temperature, high pressure, and strong corrosiveness, so the corrosion of pipelines and pressure vessels is very common. Corrosion will cause the wall thickness of the components to be thinned and the pressure-bearing performance to decrease, causing accidents such as leakage and explosion, causing casualties and economic losses. Therefore, it is necessary t...

Examples

Embodiment 1

[0066] An example of using the coil probe with iron core of the present invention to perform pulse eddy current detection on a steel pipe with a coating is given below. The test object is a 20# steel pipe with an outer diameter of 180.0mm and a wall thickness of 11.0mm. The electrical conductivity σ of the steel pipe is 4MS / m, and the relative magnetic permeability μ r It is 300, and the thickness of the outer coating of the pipe is 40mm. by The pulse eddy current diffusion time constant τ of the tested steel pipe can be calculated e = 18.5ms.

[0067] According to the test method of the probe with iron core coil, it is measured that the excitation current falling edge of the probe designed in the present invention is as Figure 4 Middle curve, measured probe time constant τ s = 0.28ms. Visible, there is Yes, it means that when using the iron core coil probe designed in the present invention to perform pulse eddy current testing on the steel pipe, the impact of the pulse eddy c...