A method for evaluating dense crack non-destructive testing and a testing device thereof

Abstract

The application is a kind of dense crack nondestructive testing evaluation method and its testing device, which is used for detecting a large number of dense small cracks formed by metal coating layer and other ultra-thin metal surface, and is suitable for detecting and evaluating metal coating layer on any metal or non-metal substrate. The application is characterized in that high-frequency eddy current sweep technology is adopted, the frequency / amplitude curve obtained when a standard workpiece without defect cracks is swept is taken as a calibration value, the frequency / amplitude data curve in the sweep process is analyzed, and the relevant equivalent value of crack density and depth of the detected metal workpiece is obtained, so as to realize the evaluation of the defect crack condition of the detected object.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, specifically to the detection of numerous dense fine cracks formed on ultra-thin metal surfaces such as metal coatings, and particularly to a nondestructive testing and evaluation method and device for dense cracks. Background Technology

[0002] Modern industrial equipment cannot function without non-destructive testing (NDT) technology. Electromagnetic eddy current (EDT) is one of the five conventional NDT techniques, enabling rapid and effective detection of fatigue cracks on metallic surfaces and providing an equivalent assessment of defect size.

[0003] As shown in Figure 1, when probe 1' scans along the X direction to detect defect 21 on metal surface 2, the magnetic field induced by the coil of probe 1' (usually composed of a coil and a magnetic core) is distorted. The instrument processes the coil-induced signal data to obtain a detection signal, and uses this signal amplitude and phase to assess the equivalent size of the defect. However, as... Figure 2 and Figure 3 As shown, when probe 1′ faces a dense crack with a size much smaller than its own scanning area, the dense crack almost covers the probe's detection surface, resulting in a uniform influence on the eddy current signal. Consequently, the induced magnetic field signal often cannot be correctly acquired and detected.

[0004] To address the above-mentioned shortcomings, the present invention adopts the following technical solution. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for nondestructive testing and evaluation of dense cracks. The disclosed technical solution is as follows:

[0006] A non-destructive testing and evaluation method and apparatus for dense cracks are disclosed. This method is used to detect numerous dense, fine cracks formed on ultra-thin metal surfaces such as metal coatings, and is applicable to the detection and evaluation of metal coatings on any metal or non-metal substrate material. The key feature is the use of high-frequency eddy current sweep technology. For dense cracks within the probe's detection area, the frequency / amplitude curve obtained during the sweep of a standard workpiece with no defects is used as a calibration value. By analyzing the frequency / amplitude data curve during the sweep process, the correlation equivalent value between the crack density and depth of the tested metal workpiece is obtained, thereby evaluating the defect crack condition of the tested object. The specific steps are as follows:

[0007] a. Obtain the calibration value of the standard workpiece: Use a defect-free crack sample that is the same as the metal workpiece being tested, select the corresponding frequency range, and obtain the frequency / amplitude data curve of the test by scanning the frequency with the probe;

[0008] b. Actual testing: Using the frequency range selected in step a, the actual workpiece is tested by scanning the frequency with the probe to obtain the frequency / amplitude data curve of the test.

[0009] c. Data Analysis: By analyzing the frequency / amplitude data curves obtained in step b and their corresponding standard equivalent values, the defect and crack situation of the tested object is analyzed and evaluated.

[0010] Furthermore, in the frequency sweep detection, a corresponding frequency range is selected. During the detection, software extracts frequency value points within the corresponding frequency range using big data. The corresponding results of the frequency sweep detection using a dense array of frequency value points are then used to form a curve for data analysis. Generally, a higher frequency alternating power supply is used to detect small surface cracks. For example, the frequency value can be set to gradually increase from 100kHz to 500kHz in a dot matrix detection mode, forming a curve value of voltage V versus frequency f. The curve changes are analyzed to obtain the equivalent value of the crack density and depth of the tested metal workpiece, thereby assessing the defect crack condition of the tested object.

[0011] Furthermore, the detection probe is composed of an array of superimposed sensors. Information data from each superimposed sensor coil is acquired through frequency sweeping. The frequency / amplitude data curves of each sensor are comprehensively analyzed, and the strength curves of the large data detection signals from the superimposed sensors are compared and analyzed to determine the equivalent value of the defect crack, thereby analyzing and assessing the specific location of the defect crack. Normally, the superimposed sensor coils are designed as planar helical coil eddy current detection sensors, with partial overlap of the planar coils. The signal data at the overlap and non-overlapping positions of the superimposed sensor coils are used as the equivalent value for detecting the defect crack to assess its specific location.

[0012] Furthermore, after extracting the frequency / amplitude data of the two superimposed sensor coils and analyzing the equivalent values, the specific location of the defect crack is evaluated. When the two coils are superimposed, they can be arranged in the sensor scanning direction, i.e., positioned at the specific location of the crack in the scanning direction, to analyze the distribution of densely packed defect cracks. Alternatively, the two superimposed coils can be designed in the transverse direction of the scanning movement to analyze the transverse distribution or length of densely packed defect cracks.

[0013] Furthermore, the method also includes extracting detection signal data from two superimposed sensor coils, which are used in turn as excitation and detection coils during alternating detection.

[0014] Furthermore, the superimposed sensor coils are three triangular superimposed coils. After extracting the frequency / amplitude data of the three coils and analyzing the equivalent values, the specific location of the defect crack is evaluated and analyzed. The transverse and longitudinal directions are superimposed together to determine the three-dimensional position.

[0015] Furthermore, the superimposed sensor coils are array-type superimposed coils. After extracting the frequency / amplitude data of two or more coils and analyzing the equivalent value, the specific location of the defect crack is evaluated and analyzed. The transverse and longitudinal directions are superimposed together to determine the three-dimensional position.

[0016] This invention also discloses a dense crack non-destructive testing device for detecting a large number of dense fine cracks formed on ultra-thin metal surfaces such as metal coatings (2). It is applicable to the detection of metal coatings (2) on any metal or non-metal substrate material, and the electrical signal is connected to the testing instrument (3). It includes a probe housing (11) and a sensor (12). The sensor (12) is characterized by having an array of several superimposed coils. It also includes a controller (13), which controls the frequency sweep method to excite the detection and acquire the detection signals of each sensor coil.

[0017] Furthermore, the two superimposed coils are used as excitation and detection coils respectively for alternating detection.

[0018] Furthermore, the controller (13) is mounted on the probe housing (11). When the controller (13) is mounted on the probe housing (11), it is integrated with the probe housing (11) and communicates with the detection instrument (3) via wireless data transmission. Alternatively, the controller (13) is mounted on the detection instrument (3) and is integrated with the detection instrument as a control module, with leads connected to the detection probe.

[0019] Based on the above technical solution, the present invention has the following beneficial effects:

[0020] This invention discloses a non-destructive testing and evaluation method and device for dense cracks. It employs high-frequency eddy current sweep technology to scan and detect dense cracks within the detection area of ​​an eddy current probe. The results are compared with standard values ​​obtained from corresponding sweep data series of crack-free standard parts to derive the equivalent values ​​of the density and depth of dense cracks in the metallic material under the eddy current probe's detection area. The sweep curves for dense cracks are compared and analyzed with the frequency / amplitude curves obtained from sweeps of standard and defect-free workpieces to evaluate the density and depth of dense cracks, enabling the collective detection and evaluation of a large number of dense cracks much smaller than the detection area of ​​the eddy current probe.

[0021] This method has been validated in the detection of cracks in micron-sized cadmium-coated layers on the surface of nuclear fuel zirconium tubes. Through frequency sweep signal processing and analysis, crack density and depth equivalent estimates can also be obtained. This invention is applicable to the detection and evaluation of metallic coatings on any metallic or non-metallic substrate material, and is particularly suitable for the detection of numerous dense, fine cracks formed on ultrathin coatings. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an existing eddy current testing probe for detecting metal defects.

[0023] Figure 2 A schematic diagram illustrating the detection of dense defect cracks using existing eddy current testing probes and evaluation methods;

[0024] Figure 3 A schematic diagram illustrating the detection of dense defect cracks using existing eddy current testing probes and evaluation methods;

[0025] Figure 4 This is a schematic diagram of the defect-free standard detection signal of the preferred embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of a dense defect crack detection signal according to the preferred embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of a dense defect crack detection signal according to the preferred embodiment of the present invention;

[0028] Figure 7 This is a schematic diagram of the detection device structure according to the preferred embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of an eddy current sensor coil structure according to a preferred embodiment of the present invention;

[0030] Figure 9 This is a schematic diagram of an eddy current sensor coil structure according to a preferred embodiment of the present invention;

[0031] Figure 10 This is a schematic diagram of an eddy current sensor coil structure according to a preferred embodiment of the present invention;

[0032] Figure 11 This is a schematic diagram of an eddy current sensor coil structure according to a preferred embodiment of the present invention;

[0033] Figure 12 This is a schematic diagram of an eddy current sensor coil structure according to a preferred embodiment of the present invention;

[0034] Figure 13 This is a schematic diagram of an eddy current sensor coil structure according to the preferred embodiment of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] like Figures 4 to 13 As shown, a method and apparatus for non-destructive testing and evaluation of dense cracks are disclosed. This method is used to detect a large number of dense, fine cracks formed on ultra-thin metal surfaces such as metal coatings. It is applicable to the detection and evaluation of metal coatings on any metal or non-metal substrate material. Figure 2 As shown, the detection method of the present invention can be applied to the detection of ultrathin interlayer spacing 21, or as... Figure 3 As shown, it is applicable to the detection and evaluation of dense, irregular crack defects.

[0037] like Figures 4 to 6 As shown, high-frequency eddy current sweep frequency technology is used to target dense cracks under the probe's detection area. The frequency / amplitude curve obtained during the sweep frequency of a standard workpiece without defects and cracks is used as the calibration value. By analyzing the frequency / amplitude data curves during the sweep frequency process, the correlation equivalent value between the crack density and depth of the tested metal workpiece is obtained, thereby assessing the defect and crack condition of the tested object. The specific steps are as follows:

[0038] d. Obtain the calibration values ​​of the standard workpiece: Use a defect-free crack sample that is the same as the metal workpiece being tested, select the corresponding frequency range, and obtain the frequency / amplitude data curve of the test by scanning the frequency with the probe;

[0039] e. Actual testing: Using the frequency range selected in step a, the actual workpiece is tested by scanning the frequency with the probe to obtain the frequency / amplitude data curve of the test.

[0040] f. Data Analysis: By analyzing the frequency / amplitude data curves obtained in step b and their corresponding standard equivalent values, the defect and crack situation of the tested object is analyzed and evaluated.

[0041] like Figure 4 , Figure 5 and Figure 6 As shown, in frequency sweep detection, a corresponding frequency range is selected. During the detection, software extracts frequency value points within the corresponding frequency range using big data. The results of the frequency sweep detection using a dense array of frequency value points are then used to form a curve for data analysis. Generally, a higher frequency alternating power supply is used to detect small surface cracks. For example, the frequency value can be set to gradually increase from 100kHz to 500kHz in a matrix detection mode, forming a curve of voltage V versus frequency f. The curve changes are analyzed to obtain the equivalent value of crack density and depth of the tested metal workpiece, thereby assessing the defect crack condition of the tested object. Figure 4 The middle section shows the data curves for the inspection of defect-free standard parts, while... Figure 5 and Figure 6The image shows a signal data curve for dense defect detection. Normally, when the crack density is wide, the curve looks like this. Figure 5 As shown, due to the lower voltage value, there will be a wider and flatter curve, while... Figure 6 The graph shown is a curve when the density of dense defect cracks is high. Due to the high voltage value, the curve will have a more prominent and sharp peak. While the graph displayed on the oscilloscope is adjustable, it allows for comparative analysis of defect crack density within a fixed frequency range. This invention's evaluation method is highly suitable for detecting and evaluating dense cracks on the opposite surfaces of ultrathin metal coatings in nuclear fuel. Cracks in thin metal coatings of nuclear fuel often occur within the coating layer or produce penetrating cracks. The probe detection of this invention is applicable to 15µm coatings of nuclear fuel, and can detect dense cracks covering 10 to 30 cracks on the probe surface.

[0042] like Figures 8 to 13 As shown, the detection probe is composed of an array of superimposed sensors. Information data from each superimposed sensor coil is acquired through frequency sweeping. The frequency / amplitude data curves of each sensor are comprehensively analyzed. The strength curves of the large data detection signals from the superimposed sensors are compared and analyzed to determine the equivalent value of the defect crack, thereby analyzing and assessing the specific location of the defect crack. Normally, the superimposed sensor coils are designed as planar helical coil eddy current detection sensors. The superimposed eddy current detection sensors are configured with partial overlap of the planar coils. The signal data at the overlap and non-overlapping positions of the superimposed sensor coils are used as the equivalent value for detecting the defect crack to assess its specific location.

[0043] like Figure 8 As shown, after extracting the frequency / amplitude data of two superimposed sensor coils and analyzing their equivalent values, the specific location of the defect crack is evaluated. When the two coils are superimposed, they can be arranged in the sensor scanning direction, i.e., positioned at the specific location of the crack in the scanning direction, for analyzing the distribution of densely packed defect cracks. Alternatively, the two superimposed coils can be designed in the transverse direction of the scanning movement, for analyzing the transverse distribution or length of densely packed defect cracks. The method also includes extracting the detection signal data from the two superimposed sensor coils, which are used sequentially and alternately as excitation and detection coils for alternating detection.

[0044] like Figure 9 As shown, the sensor coils are three overlapping coils in a triangular configuration. After extracting the frequency / amplitude data of the three coils and analyzing the equivalent values, the specific location of the defect crack is evaluated and analyzed. The transverse and longitudinal directions are superimposed together to determine the three-dimensional position.

[0045] like Figures 10 to 13 As shown, the superimposed sensor coils are arrayed superimposed coils. Frequency / amplitude data from two or more coils are extracted and analyzed to determine the equivalent value, thus assessing the specific location of the defect crack. The transverse and longitudinal data are superimposed together to determine the three-dimensional location. For example... Figure 10 As shown, when circular coils are arranged in an array, the frequency / amplitude data of two adjacent superimposed coils are used as equivalent values ​​for comparative analysis to assess the density, size, and depth of defects and cracks; or as... Figure 13 As shown, when square coils are arranged in an array, the detection data values ​​of two adjacent superimposed coils are extracted for analysis and evaluation. And as... Figure 11 As shown, the sensor coils, designed with multiple rows of arrays, analyze three or more superimposed detection data points and use big data software to analyze and compare the specific parameter values ​​of defects and cracks.

[0046] like Figure 6 and Figure 7 As shown, this invention also discloses a dense crack non-destructive testing device for detecting a large number of dense fine cracks 22 formed on an ultra-thin metal surface such as a metal coating layer 2. It is applicable to the detection of metal coatings 2 on any metal or non-metal substrate material, and the electrical signal is connected to a testing instrument 3. It includes a probe housing 11 and a sensor 12, characterized in that the sensor 12 has a plurality of superimposed coil arrays; it also includes a controller 13, which controls a frequency sweep method to excite and acquire the detection signals of each sensor coil.

[0047] like Figure 8 , Figure 12 As shown, two coils superimposed on each other serve as the excitation and detection coils, respectively, for alternating detection. The two coils can be circular planar helical coils or square planar coils.

[0048] like Figure 7 As shown, the controller 13 is mounted on the probe housing 11. When the controller 13 is mounted on the probe housing 11, it is integrated with the probe housing 11 and communicates with the testing instrument 3 via wireless data transmission. Alternatively, the controller 13 is mounted on the testing instrument 3 and integrated with the testing instrument as a control module, with leads connected to the testing probe.

[0049] The above is one embodiment of the present invention. Furthermore, it should be noted that any equivalent or simple variations made to the structure, features, and principles described in this patent concept are included within the scope of protection of this patent.

Claims

1. A method for nondestructive testing and evaluation of dense cracks, characterized in that... High-frequency eddy current sweep frequency technology is employed to target dense cracks within the probe's detection area. The frequency / amplitude curves obtained during the sweep frequency analysis of a standard workpiece without defects and cracks are used as calibration values. By analyzing the frequency / amplitude data curves during the sweep process, the correlation equivalent values ​​between the crack density and depth of the inspected metal workpiece are derived, thereby assessing the defect and crack condition of the inspected object. The specific steps are as follows: a. Obtaining the calibration value of a standard workpiece: Using a defect-free crack sample identical to the metal workpiece being tested, a corresponding frequency range is selected, and the frequency / amplitude data curve is obtained by scanning the frequency with a probe. The probe is composed of an array of superimposed sensors. The information data of the superimposed sensor coils are obtained by scanning the frequency, and the frequency / amplitude data curves of each sensor are comprehensively analyzed. The strength curves of the large data detection signals of the superimposed sensors are compared and analyzed to determine the equivalent value of the defect crack, so as to analyze and evaluate the specific location of the defect crack. b. Actual testing: Using the frequency range selected in step a, the actual workpiece is tested by scanning the frequency with the probe to obtain the frequency / amplitude data curve of the test. c. Data Analysis: By analyzing the frequency / amplitude data curves obtained in step b, extract the detection signal data when the two superimposed sensor coils are used alternately as excitation and detection coils for alternating detection, and analyze and evaluate the defect and crack situation of the object being inspected by corresponding standard equivalent values.

2. The method for nondestructive testing and evaluation of dense cracks according to claim 1, characterized in that... The frequency sweep detection selects a corresponding frequency range, and during the detection, the software extracts frequency value points within the corresponding frequency range using big data. The corresponding results of the frequency sweep detection of the dense array frequency value points are then used to form a curve for data analysis.

3. The method for nondestructive testing and evaluation of dense cracks according to claim 1, characterized in that... After extracting the frequency / amplitude data of the two superimposed sensor coils and analyzing the equivalent values, the specific location of the defect crack is evaluated and analyzed.

4. The method for nondestructive testing and evaluation of dense cracks according to claim 1, characterized in that... The sensor coils are three overlapping coils in a triangular configuration. The frequency / amplitude data of the three coils are extracted and analyzed to determine the equivalent value. The specific location of the defect crack is then evaluated and analyzed. The transverse and longitudinal data are superimposed together to determine the three-dimensional location.

5. The method for nondestructive testing and evaluation of dense cracks according to claim 1, characterized in that... The superimposed sensor coils are arrayed superimposed coils. After extracting the frequency / amplitude data of two or more coils and analyzing the equivalent value, the specific location of the defect crack is evaluated and analyzed. The transverse and longitudinal directions are superimposed together to determine the three-dimensional position.

6. A non-destructive testing device for dense cracks, employing any one of the testing and evaluation methods as described in claims 1-5, comprising a probe housing (11) and a sensor (12), characterized in that... The sensor (12) is composed of several superimposed coil arrays; It also includes a controller (13), which controls the frequency sweep method to excite and detect the detection signals of each sensor coil.

7. The dense crack non-destructive testing device according to claim 6, characterized in that... The two superimposed coils are used as excitation and detection coils respectively for alternating detection.

8. The dense crack non-destructive testing device according to claim 7, characterized in that... The controller (13) is mounted on the probe housing (11).

Images