A new type of comparison block for TOFD technology partitioning

Abstract

A new type of comparison test block for TOFD detection technology zoning, including a comparison test block with a rectangular structure, wherein an artificial defect is processed inside the comparison test block, wherein the artificial defect is a groove with a sharp angle, wherein the direction of the artificial defect is consistent with the scanning direction, and wherein the artificial defect has an angle with the upper surface of the comparison test block. The artificial defect is an artificial defect with a rhombus cross section, and the connecting line of the upper and lower sharp angles of the rhombus artificial defect is substantially perpendicular to the upper surface of the comparison test block. The comparison test block of the present invention is small in size, low in cost, and easy to process.

Description

Technical Field

[0001] The present invention relates to the field of nondestructive testing, and in particular to a comparison test block for zoning using a novel TOFD testing technology. Background Art

[0002] TOFD detection technology has been increasingly used internationally in recent years, especially for thick-walled pressure-bearing equipment. Compared with traditional detection methods such as X-ray detection, it has the advantages of large detection thickness, high detection sensitivity and strong sensitivity to crack-type defects. In TOFD detection, the echo test block with gain setting is mainly the diffraction signal from the tip of the defect. The amplitude of the diffraction signal has nothing to do with the size of the defect and the detection accuracy. Usually, we require the amplitude of the starting wave of the time window to ensure that the defect diffraction signal will be effectively received and observed. The intensity of the diffraction signal has nothing to do with the area of ​​the flat-bottom hole, so the flat-bottom hole is not suitable for TOFD amplitude calibration, which means that it is not ideal to use the bottom wave to calibrate the amplitude of the straight wave or the time start window for thick workpieces (thickness greater than 50mm).

[0003] Based on the analysis of the blind spots in thick-wall TOFD detection, a method of using layered detection to reduce the detection blind spots is proposed. Combined with theoretical calculations and test results of comparative test blocks, the layered detection parameters are proposed and optimized. Domestic TOFD detection standards NB / T47013.10 and DL / T330, which are relatively mature and familiar to everyone, all propose that the thickness direction should be divided for detection of products and workpieces with a thickness greater than 50 mm when formulating the detection process. The NB / T47013.10 standard proposes TOFD-A~TOFD-E comparison test blocks. From the perspective of the requirements and size of the comparison test blocks, this comparison test block is difficult to process. As the detection thickness changes, the comparison test block continues to increase in the thickness direction, and the weight will continue to increase. The economic cost of this test block is high and it is not easy to carry.

[0004] In recent years, there are more and more large-scale hydropower stations, and the requirements for the quality of metal structure welding in power stations are becoming more and more stringent. In the construction of hydropower stations, there are more and more detection products with a thickness of more than 50-200mm. In industry, there are more and more reaction vessels with a wall thickness of more than 100mm and high temperature and high pressure requirements, and the thickest wall thickness can reach 350mm. When testing thick-walled pressure vessels, it has the advantages of high detection sensitivity, sensitivity to crack defects, and accurate quantitative determination of defects, making TOFD technology a new detection technology with great development prospects in weld detection and defect quantification. However, when TOFD testing thick plate products, the coverage of the detection depth and the detection sensitivity should be verified at the depth of the test block before testing. This link directly restricts the detection rate of product defects.

[0005] From the inspection standards and TOFD technical principles, it can be known that each set of calculated time parameter inspection parameters should be verified on the comparison test block during thick plate inspection, and each set of inspection parameters should be set for detection sensitivity. However, according to the current domestic inspection situation, most inspection sites are not equipped with TOFD-C~TOFD-E test blocks due to factors such as the weight, volume and price of the comparison test blocks. Therefore, it is necessary to produce a comparison test block for TOFD inspection technology partitions that is practical, cheap and easy to use on site. Summary of the invention

[0006] The invention provides a novel comparison test block for zoning in TOFD detection technology to solve the problems existing in the prior art.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A new type of comparison test block for TOFD detection technology zoning includes a comparison test block with a rectangular structure, wherein an artificial defect is processed inside the comparison test block, wherein the artificial defect is a groove with a sharp angle, the direction of the artificial defect is consistent with the scanning direction, and the artificial defect has an angle with the upper surface of the comparison test block.

[0009] The artificial defect is an artificial defect with a rhombus-shaped cross section, and a line connecting the upper and lower sharp corners of the rhombus-shaped artificial defect is substantially perpendicular to the upper surface of the comparison test block.

[0010] The artificial defect is a rhombus-shaped sharp-angle artificial defect with upper and lower sharp angles of 60°.

[0011] The upper surface of the comparison test block may have a rectangular groove of a set height, and the rectangular groove is located directly above the artificial defect.

[0012] The minimum distance between the artificial defect and the upper surface of the comparison test block is greater than 0 mm.

[0013] The maximum value of the artificial defect distance from the upper surface of the comparison test block is not less than the thickness of the product being tested.

[0014] The surface of the test block is marked with scales along the scanning direction.

[0015] Beneficial effects of the present invention:

[0016] The comparison test block of the present invention has small size, low cost and convenient processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a front view of a comparison test block for partitioning of a novel TOFD detection technology according to the present invention;

[0018] Figure 2 yes Figure 1AA cross-sectional view of the comparison test block shown in;

[0019] Figure 3 yes Figure 1 A cross-sectional view of the comparison test block shown in ;

[0020] Figure 4 yes Figure 3 Schematic diagram of artificial defects in the comparison test block shown in;

[0021] Figure 5 This is the principle of using a new type of comparison test block for TOFD detection technology partitioning described in the present invention;

[0022] Figure 6 A comparative test block scanning diagram for a novel TOFD technology partitioning method according to an embodiment of the present invention;

[0023] Figure 7 This is the detection spectrum after calibration on the TOFD-C comparison test block;

[0024] Figure 8 This is the detection spectrum after calibration on the new test block.

[0025] Among them, 1-artificial defect; 2-rectangular groove; X-horizontal scale value on the upper surface of the test block; h-the distance from the upper tip of the artificial defect to the workpiece surface corresponding to the X value on the upper surface of the test block; h1-the minimum distance from the upper tip of the artificial defect to the workpiece surface; h2-the minimum distance from the upper tip of the artificial defect to the workpiece surface. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] The present invention provides a new type of comparison test block for TOFD detection technology zoning, the comparison test block is a comparison test block of a rectangular parallelepiped structure, a groove-shaped artificial defect is processed inside the comparison test block, and the upper part of the groove-shaped artificial defect has an upward groove. The artificial defect is preferably a rhombus-shaped groove-shaped artificial defect along the radial section, and the upper and lower sharp corners of the rhombus-shaped artificial defect are basically perpendicular to the upper surface of the comparison test block. The basically perpendicular means that the vertical error is within a set range, and the two can be considered to be perpendicular. The direction of the artificial defect is consistent with the scanning direction, and the artificial defect has an angle with the upper surface of the comparison test block.

[0032] The above processing method can be processed by an EDM CNC wire cutting machine, which will form a wire cutting feed slot on the test block. During the processing, it is necessary to ensure that the above artificial defect 1 is parallel to the horizontal axis, the height error of the artificial defect is less than 0.05mm, and the verticality of the diamond artificial defect is not more than 0.1° (i.e. vertical error). Other technical requirements of the test block shall comply with the requirements specified in JB / T8428.

[0033] The upper surface of the comparison test block may have a rectangular groove 2 of a set height, the rectangular groove 2 is located directly above the artificial defect 1, and the specification of the rectangular groove may be selected to be 0.5 mm×0.5 mm.

[0034] The minimum distance between the artificial defect and the upper surface of the comparison test block is greater than 0 mm and generally less than 20 mm; the maximum distance between the artificial defect and the upper surface of the comparison test block is not less than the thickness of the product being tested.

[0035] The material of the comparison test block should be similar or identical to the acoustic properties of the workpiece under test. The differences in sound velocity and material attenuation coefficient α in different directions caused by the anisotropy of steel must be considered when determining whether the acoustic properties of the comparison test block and the workpiece under test are similar. The materials used to process the comparison test block must be strictly tested by MT, UT, PA and other methods, and there must be no flat-bottom hole equivalent defects greater than or equal to φ2 in the area where the sound beam of the test block passes.

[0036] That is, the material should be tested before making the above-mentioned comparison test blocks. When the internal defects of the material are smaller than a certain equivalent pore size, the material can be considered to be defect-free and the comparison test blocks can be made.

[0037] When there is a defect inside the workpiece, the waveforms received by the probe are: straight wave, diffraction wave at the top tip of the defect, diffraction wave at the bottom tip of the defect, bottom echo, shear wave signal or other waveform conversion signal, and the sharper the defect tip, the more obvious the diffraction signal. When using partition detection, usually except for one zone, the straight wave cannot be seen within the time range of other detection zones. The setting of the TOFD partition detection time window is generally based on the calculation adjustment time window, and this time window is usually impossible to verify.

[0038] In order to accurately find the diffraction wave at the tip of the defect, a comparison test block with a sharp-angle defect is an ideal test block. The new comparison test block is used to focus on the diffraction wave signal that should be generated at a certain depth, and the A-scan time and amplitude of the diffraction wave are analyzed and studied to set the detection time range and detection sensitivity of the area. Therefore, the defect of the present invention adopts a diamond-shaped artificial defect, and when an artificial sharp-angle defect is used, the sharp angle of the defect is 60°.

[0039] When processing artificial defects, the present invention preferably adopts CNC wire cutting to process the above-mentioned comparison test block. During the processing, it is ensured that the above-mentioned artificial defects should be parallel to the horizontal axis, the height error of the artificial defects is less than 0.05mm, and the verticality of the diamond-shaped artificial defects is not greater than 0.1°.

[0040] The following is the use effect and verification of the comparative test block of the present invention:

[0041] Verification of time window:

[0042] Usually, when thick workpieces (>50mm) are inspected, the workpiece thickness is divided into sections, and a certain depth of coverage is set on adjacent sections. The present invention only takes the above coverage as an example. Figure 5. It can be seen that the time setting window corresponding to the first zone (PCS1) is set to t1~t2, and the corresponding detection depth is 0-A, that is, 0~h2 in the right figure. The time setting window corresponding to the second zone (PCS2) is set to t1'~t2', and the corresponding detection depth should include the coverage thickness BC, that is, h1~T in the right figure. When using the new comparison test block for verification (right figure), the first zone places the PCS1 scanning frame in the center at the horizontal position of A. At this time, the diffraction wave signal of point A should be observed at the end position of the time window. The second zone places the PCS2 scanning frame in the center at the horizontal position of B. At this time, the diffraction wave signal of point B should be observed at the starting position of the time window. Only then can it be proved that the time window setting meets the coverage requirements, that is, the calculation time window parameters are verified.

[0043] Verification of scanning sensitivity:

[0044] When testing in zone 1, 40% to 80% of the through wave height can be used as the scanning sensitivity, or Figure 5 In the 0-A depth range, the 40%~80% of the weakest diffraction signal wave produced by the comparison test block is used as the scanning sensitivity. Figure 5 The scanning sensitivity is 40%~80% of the weakest signal wave of the diffraction signal generated by the comparison test block within the mid-BC depth range.

[0045] Effect verification during actual use:

[0046] For this purpose, WSD690 material and 65mm thick high-strength steel were used to process Figure 1 The test block is used for comparison and verification. The OmniScan MX2 test equipment is used, and the upper and lower partitions are both equipped with 5MHz φ6mm probes. The wedge angle is 60°, and the probes are placed on the same horizontal plane (that is, the probe offset is 0). Under this configuration, a non-parallel scanning method is used. The test data map is as follows Figure 6 shown.

[0047] Figure 6 The data was collated and analyzed, and the A-scan amplitudes of artificial defects at different heights were collated and compared. The specific data comparison is shown in Table 1. As can be seen from Table 1, the first zone adopts 80% calibration of the direct wave height, and the resulting diffraction signal amplitude is low. The maximum difference of the A-scan amplitude of the artificial defect diffraction signal at different scanning distances is 19.6%, and the A-scan amplitude of the diffraction signal decreases significantly with the increase of the defect depth. The second zone adopts 80% calibration of the artificial defect diffraction signal amplitude, and the resulting diffraction signal amplitude is large. The A-scan amplitude of the artificial defect diffraction signal at different defect depths does not change significantly, and the A-scan amplitude of the diffraction signal changes irregularly with the increase of the scanning distance. Therefore, when using this comparison test block, after the second zone (including the second zone), 60%~80% of the diffraction time difference signal wave generated at any depth within the depth coverage range can be used as the scanning sensitivity of the zone.

[0048]

[0049] In order to verify the effect of the comparison block, the author conducted a set of experiments, using the same detection parameters, two sets of 5MHz60° probe pairs, PCS1=60mm, PCS2=205mm, and a centered non-parallel scanning method. The two-zone scanning sensitivity was set on the TOFD-C comparison block, and the defective workpiece was detected to obtain Spectrum 1. The two-zone scanning sensitivity was set on the comparison block for the new TOFD technology partition, and the defective workpiece was detected to obtain Spectrum 2. The detection data of Spectrum 1 and Spectrum 2 were compared.

[0050] Spectrum 1 Detection technical requirements: The material of the workpiece to be inspected is WSD690 material, thickness 65mm, the sensitivity of the first zone detection is 80% of the straight wave height, and the sensitivity of the second zone detection is 80% of the weakest signal wave height of the corresponding depth side hole within the TOFD-C depth coverage range (the φ5mm side hole with a depth of 40mm is the weakest signal), chemical paste is used as the coupling agent, and the data analysis spectrum is shown in Figure 7 .

[0051] Spectrum 2 detection technical parameters: the material of the workpiece to be inspected is WSD690 material, thickness 65mm, the sensitivity of the first zone detection is 80% of the direct wave height, and the sensitivity of the second zone detection is 80% of the diffraction signal of the artificial defect of the comparison test block with a depth of 23mm~55mm for the new TOFD technology partition. Chemical paste is used as a coupling agent. The data analysis spectrum is shown in Figure 8 The comparison of the data of Spectrum 1 and Spectrum 2 is shown in Table 2.

[0052]

[0053] The new comparison test block mainly affects the data of the second zone and later. Figure 7 and Figure 8 It can be seen that the defect detection rate is consistent. From Table 2, it can be seen that for the amplitude of the highest wave of diffraction waves generated at the defect, the new comparison test block verifies the sensitivity and obtains a spectrum, and the amplitude of the defect at the same position is higher. It can be understood that the sensitivity of the new test block is higher than that of the TOFD-C comparison test block.

[0054] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0055] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A new type of comparison test block for TOFD detection technology partitioning, characterized by: A comparison test block comprising a rectangular parallelepiped structure, wherein an artificial defect is processed inside the comparison test block, wherein the artificial defect is a groove with a sharp angle, wherein the direction of the artificial defect is consistent with the scanning direction, and wherein the artificial defect forms an angle with the upper surface of the comparison test block; The artificial defect is an artificial defect with a rhombus-shaped cross section, and a line connecting the upper and lower sharp corners of the rhombus-shaped artificial defect is substantially perpendicular to the upper surface of the comparison test block; The upper surface of the comparison test block may have a rectangular groove of a set height, and the rectangular groove is located directly above the artificial defect.

2. A comparison test block for the new TOFD detection technology partitioning according to claim 1, characterized in that: The artificial defect is a rhombus-shaped sharp-angle artificial defect with upper and lower sharp angles of 60°.

3. A comparison test block for the new TOFD detection technology partition according to claim 1, characterized in that: The minimum distance between the artificial defect and the upper surface of the comparison test block is greater than 0 mm.

4. A comparison test block for the new TOFD detection technology partitioning according to claim 1, characterized in that: The maximum value of the artificial defect distance from the upper surface of the comparison test block is not less than the thickness of the product being tested.

5. A comparison test block for the new TOFD detection technology partitioning according to claim 1, characterized in that: The surface of the test block is marked with scales along the scanning direction.

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