Corrosion defects Visual imaging and evaluating method based on alternating current electromagnetic fields

A technology of alternating electromagnetic fields and defects, applied in the direction of material magnetic variables, etc., can solve the problems of complex surface contour and three-dimensional shape, difficult surface contour imaging and evaluation, etc.

Active Publication Date: 2019-09-17
CHINA UNIV OF PETROLEUM (EAST CHINA)
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Problems solved by technology

[0004] Compared with crack defects, corrosion defects have complex surface contours and three-dimensional shapes, and traditional characteristic signals Bx, Bz and butterfly diagrams cannot realistically det

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  • Corrosion defects Visual imaging and evaluating method based on alternating current electromagnetic fields
  • Corrosion defects Visual imaging and evaluating method based on alternating current electromagnetic fields
  • Corrosion defects Visual imaging and evaluating method based on alternating current electromagnetic fields

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Embodiment 1

[0026] figure 1 The flow chart of the visual imaging and evaluation method of corrosion defects based on AC electromagnetic field detection technology provided by the embodiment of the present invention includes:

[0027] S1, prepare a carbon steel test block, with corrosion defects on the surface of the test block, such as figure 2 As shown, the diameter of the corrosion defect is 10.0mm, and the depth is 0.5mm. Define the probe scanning direction as the X direction, adopt the grid scanning method, and use the AC electromagnetic field detection probe to detect 40×40mm along the scanning path at the same height plane on the surface of the corrosion defect of the test block 2 area, such as image 3 shown. The scan step length in the X direction is 0.5mm, the number of equally spaced points on the scan path in the X direction is 80, the distance between the scan paths in the Y direction is 1.0mm, and the number of equally spaced scan paths in the Y direction is 40, to obtain...

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Abstract

The present invention discloses a corrosion defects Visual imaging and evaluating method based on alternating current electromagnetic fields and relates to the technical field of non-destructive testing defect imaging. The method comprises: obtaining scan results of a magnetic field signal Bz amplitude matrix of an alternating electromagnetic field corrosion defect surface by means of a grid scanning method, obtaining a gradient field matrix of a maximum distortion value of a distortion magnetic field signal Bz by using a gradient field, reflecting aggregation situation of an induced current at an edge of the corrosion defects, further obtaining an intuitive imaging result of a surface profile of the corrosion defects by obtain of an extremum, background removal, normalizing operation, and grading conversion, and using a ratio of white pixels to total pixels in a grayscale image and multiplying by a scanning area, to obtain an exact area of the corrosion defects. The method is conducive to visual assessment of the corrosion defects and accurate prediction of remaining life.

Description

technical field [0001] The invention relates to the technical field of non-destructive testing defect imaging, in particular to a corrosion defect imaging and evaluation method based on AC electromagnetic field detection technology. Background technique [0002] Marine structures have served in seawater environment for a long time. Due to the corrosion of seawater, various corrosion defects are easily produced on the surface of the structure. Due to factors such as coating coverage and accumulation of attachments, traditional non-destructive testing techniques need to detect and evaluate defects in the process of cleaning up attachments in a large area and completely destroying the coating during the inspection of underwater structures. The operation process is complex and inefficient. , structural surface cleaning and coating repair costs are high. [0003] Alternating Current Field Measurement (ACFM) technology is a new electromagnetic non-destructive testing technology, ...

Claims

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Application Information

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IPC IPC(8): G01N27/83
CPCG01N27/83
Inventor 袁新安李伟陈国明赵建明王振翔刘阳王勇胜王克宇
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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