An eddy current c-scan imaging detection method

Abstract

An eddy current C-scan imaging detection method. First, the impedance change waveform of the defect comparison test block is collected; the real part and the imaginary part of the impedance change waveform are respectively high-pass filtered, and the filtered real part and the imaginary part are noised respectively. Statistics, extract the defect signal area; separate the lift-off signal from the defect signal area; then calculate the impedance amplitude, phase angle and impedance increment of the filtered impedance change waveform in the defect signal area, and extract the area after fusion. The envelope diagram of the impedance amplitude spectrum in the same defect, so as to obtain the corrected defect amplitude spectrum; through the threshold segmentation of the corrected defect amplitude spectrum, the defect trend in the preliminary eddy current C-scan imaging image is extracted, and different biases are established. The relationship curve between the angle and the maximum amplitude of the defect; and use the relationship curve to perform amplitude correction on the defect orientation and preliminary eddy current C-scan imaging. It can accurately judge the defect position, length and direction information, and the defect size quantitative accuracy is high.

Description

technical field [0001] The invention relates to the field of image detection, in particular to an eddy current C-scan imaging detection method. Background technique [0002] Eddy current testing is a non-destructive testing method based on the principle of electromagnetic induction, which is suitable for conductive materials. The basic principle is that when a conductor is placed in an alternating magnetic field, an induced current exists in the conductor, that is, an eddy current is generated. Due to the change of various factors of the conductor itself (such as conductivity, magnetic permeability, shape, size and defect, etc.), the change of eddy current will be caused. This phenomenon is used to determine the detection method of conductor properties and states. Combining computer technology and digital signal processing technology, it can realize fast and effective detection of materials and components. [0003] Combining eddy current inspection with an automated scanni...

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Problems solved by technology

[0004] However, the eddy current C-scan imaging has the following problems: 1) Impedance variation imaging is generally used in the eddy current C-scan imaging method, and the impedance presents a fluctuating law, and the size of the defect corresponds to the gray value of the image non-linearly, so that the inspectors cannot be more accurate. Judging the length, size and other information of the defect; 2) Due to the interference of the lift-off noise and the electrical noise of the automatic scanning device, there are false defects in the C-scan image

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