Electromagnetic resonance-based nondestructive testing method for metal material

Abstract

The invention discloses an electromagnetic resonance-based nondestructive testing method for metal materials. According to the method, responding resonance signals of eddy current testing are obtained through multipled resonant capacitors in testing coils, comparative analysis of the responding resonance signals is carried out, and the relationships between a defect size and a signal amplitude and between defect depth and a signal phase are calibrated in advance, thereby enabling convenient nondestructive testing of metal materials. The electromagnetic resonance-based nondestructive testing method not only can produce same defect detection effects as a plurality of conventional electromagnetic testing methods like single-frequency eddy current and pulsed eddy current do, but also can effectively detect internal defects in a workpiece and detect workpieces with complicated surface conditions such as a casting surface, an unsmooth surface, a surface with oil stains, a rust-resisting paint, a corrosion layer or other pollutants, etc., without contact under the condition of a high liftoff value; according to the method, no cleaning is needed for test pieces, and particularly, no cumbersome processes like magnetization and demagnetization of magnetic metal materials are needed.

Description

technical field [0001] The invention relates to a nondestructive testing method, in particular to a nondestructive testing method for metal materials based on electromagnetic resonance. Background technique [0002] With the vigorous development of the socialist market economy and the substantial increase in the degree of industrialization, the application of various mechanical equipment in various industries is becoming more and more popular. With the extensive application of various mechanical equipment, its potential safety hazards have gradually emerged. Non-destructive testing is one of the direct and effective means to discover such safety hazards. Conventional methods of non-destructive testing include ultrasonic testing, radiographic flaw detection, electromagnetic testing such as magnetic particle, magnetic flux leakage, penetration and eddy current. Ultrasonic testing has a wide range of detection objects, and the defect location is relatively accurate, but it has...

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Problems solved by technology

In the electromagnetic eddy current testing method, the conventional eddy current testing method, pulsed eddy current testing method, near-field eddy current, far-field eddy current, multi-frequency eddy current testing and other methods have been developed. The currently used methods are only suitable for detecting metal surface defects, not for testing For the deep internal defects of metal materials, for eddy current detection of ferromagnetic materials, the magnetic permeability changes with the change of the external alternating magnetic field formed by the excitation current, making the eddy current signal change unstable, which seriously interferes with the detection of ferromagnetic materials by eddy current instruments. For flaw detection, saturation magnetization is required

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