Permanent magnet-based magnetic saturation pulsed eddy current infrared nondestructive evaluation method

Abstract

The invention discloses a permanent magnet-based magnetic saturation pulsed eddy current infrared nondestructive evaluation method. Firstly, a computer controls a program controller to synchronously trigger an induction heater and a thermal infrared imager, the induction heater applies pulse current excitation to a heating coil connected with a heating head while receiving a trigger signal, and acooling device cools the induction heater, the heating head and the heating coil at the same time; a strong static magnetic field is generated around the permanent magnet, a ferromagnetic material reaches magnetic saturation under the action of a permanent magnet, then joule heat is generated under the action of the heating coil, and the surface temperature of the material is changed through heatconduction; and finally, temperature changes are collected through a thermal infrared imager, and defect nondestructive evaluation is conducted on the ferromagnetic material by analyzing the collectedimage sequence. Compared with a traditional pulsed eddy current infrared nondestructive detection method, the method has the advantages that the detection depth of the ferromagnetic material is larger, and the application prospect is wide.

Description

technical field [0001] The invention relates to the field of pulsed eddy current infrared nondestructive detection of ferromagnetic material defects, in particular to a magnetic saturation pulsed eddy current infrared nondestructive evaluation method based on permanent magnets. Background technique [0002] Ferromagnetic materials are one of the main pillar materials of modern industrial and agricultural production. The products of ferromagnetic materials are indicators of a country's economic development, and their demand can roughly reflect the national living standards of a country. As a basic functional material, ferromagnetic materials are used in all aspects of life. At present, ferromagnetic materials are mainly used in telecommunications, motors, televisions and computer storage devices. Various defects in ferromagnetic materials and workpieces are serious hidden dangers in modern industrial equipment, products and weapons. Therefore, in industrial production, ferrom...

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Problems solved by technology

[0004] Since the excitation frequency used by pulsed eddy current infrared is very high, and the relative magnetic permeability of ferromagnetic materials is very large, the penetration depth of the eddy current field is small when using pulsed eddy current infrared nondestructive testing method to detect ferromagnetic materials. That is, the depth of the Joule heat source is very small, so it is difficult to detect defects at relatively deep positions in ferromagnetic materials

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