A method for detecting defects in the fine turning surface of the cladding corrosion-resistant layer on a pump product and a simulated defect comparison test block

Abstract

The present invention discloses a method for detecting defects on the fine turning surface of a corrosion-resistant layer welded on a pump product, comprising the following steps: S1, evaluating defects to be detected and making simulated defect comparison test blocks; S2, formulating a detection process plan; S3, calibrating detection equipment; S4, implementing detection and recording all relevant signals; S5, evaluating and judging defects; S6, repairing defects exceeding the standard; S7, re-inspecting according to the original process. The present invention also discloses a simulated defect comparison test block for the method for detecting defects on the fine turning surface. The present invention is suitable for the early stage inspection of the fine turning surface with higher requirements for corrosion resistance. Through the identification, analysis and comparison of simulated defects, the nature and size of defects on the fine turning surface can be effectively identified, and the situation of the defects can be judged in advance, and the defects exceeding the standard can be processed to improve the one-time inspection pass rate of the fine turning surface.

Description

Technical Field

[0001] The invention relates to a nondestructive testing technology for mechanical manufacturing, and more specifically to a method for detecting defects on a fine turning surface of a cladding corrosion-resistant layer on a pump product and a simulated defect comparison test block. Background Art

[0002] Overlay welding is a process for modifying the surface of a material. Through welding technology, a material with certain properties is deposited on the surface of a workpiece to obtain a deposited metal layer with special properties such as wear resistance, heat resistance, and corrosion resistance, or to restore the insufficient size of the workpiece caused by wear or processing errors. The purpose of overlay welding is different from that of general welding methods. It is not to connect weldments, but to modify the surface of the workpiece to improve its performance.

[0003] Overlay welding technology has been well developed in the manufacturing industry and is used in many industrial fields, such as mining machinery, conveying machinery, metallurgical machinery, power machinery, agricultural machinery, automobiles, petroleum equipment, chemical equipment, construction, manufacturing and maintenance of tools, molds and metal structures, aerospace, manufacturing and maintenance, shipbuilding and power, machinery and foundry industries, etc.; oil drilling industry, steel industry, power plants, energy machinery, nuclear power; machinery, energy, transportation, power and metallurgical industries; environmental protection fields, such as the application of gate valve laser overlay welding technology.

[0004] Many weld overlays are in the final state of finishing when they are used. It is sufficient to have no defects on the finishing surface. However, in reality, there are often a large number of defects on the finishing surface, which reduces the corrosion resistance of the weld overlay. It can only be remedied by repair welding, which wastes manpower and material resources, affects the delivery cycle, and affects other processed dimensions. At present, there are many ways to detect weld overlays, such as ultrasonic test block comparison technology and penetrant flaw detection. Among them, the existing ultrasonic test block comparison is relatively broad and cannot predict the nature and size of defects in the weld overlay; penetrant flaw detection only checks the finishing surface. If there is an excess, it must be repaired. This method cannot play a predictive role, and this situation is particularly prominent in the pump industry. Summary of the invention

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for detecting defects on the fine-turning surface of the corrosion-resistant layer welded on a pump product and a simulated defect comparison test block, which is suitable for the early inspection of the fine-turning surface with higher requirements for corrosion resistance. Through the identification, analysis and comparison of simulated defects, the depth and size of defects on the fine-turning surface can be effectively identified, the defect situation can be judged in advance, and defects exceeding the standard can be processed, thereby improving the one-time inspection pass rate of the fine-turning surface.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides a method for detecting defects in a fine turning surface of a cladding corrosion-resistant layer on a pump product, comprising the following steps:

[0008] S1, evaluate the defects to be detected and make simulated defect comparison test blocks;

[0009] S2, formulate the testing process plan;

[0010] S3, testing equipment calibration;

[0011] S4, detection implementation and recording of all relevant signals;

[0012] S5, assessment and judgment of defects;

[0013] S6, repair of defects exceeding the standard;

[0014] S7, re-inspect according to the original process.

[0015] Preferably, the step S1 specifically includes:

[0016] Prepare in advance the types and sizes of defects that are not allowed to exist on the finished surface of the weld overlay layer for evaluation, and establish the allowable range of defects;

[0017] According to the qualified range specified in the standard, the simulated defect comparison test block is designed and manufactured.

[0018] Preferably, the step S2 specifically includes:

[0019] The test plate is welded according to the same process parameters, and the simulated defect reflector is processed. The defect depth is consistent with the fine turning surface of the cladding layer.

[0020] Preferably, in step S3, the detection equipment calibration includes detection sensitivity, scanning direction, and scanning speed.

[0021] Preferably, the step S5 specifically includes:

[0022] Evaluate whether all detected defects are exposed on the machined surface after fine turning, and whether the exposed defects are within the qualified range. Record and track qualified defects, and mark the corresponding size information for defects that exceed the standard.

[0023] The second aspect of the present invention provides a simulated defect comparison test block used in the method for detecting defects in a fine turning surface according to the first aspect of the present invention, comprising a test block body;

[0024] The test block body is configured as a rectangular body;

[0025] The test block body is provided with a corrosion-resistant layer made of the same material and the same process as the pre-inspected workpiece;

[0026] The test block body is provided with a first reflector, a second reflector, a third reflector, a fourth reflector, a fifth reflector and a sixth reflector;

[0027] The first reflector, the second reflector, and the third reflector are located on one side of the center line of the test block body, and the fourth reflector, the fifth reflector, and the sixth reflector are located on the other side of the center line of the test block body.

[0028] Preferably, the first reflector, the second reflector and the third reflector are all configured as cylindrical holes with hemispherical bottoms;

[0029] The fourth reflector, the fifth reflector and the sixth reflector are all configured as cylindrical holes with a flat bottom.

[0030] Preferably, the diameter of the first reflector is 1.5 mm ± 0.1 mm, the diameter of the second reflector is 2 mm ± 0.1 mm, and the diameter of the third reflector is 3 mm ± 0.1 mm;

[0031] The distance between the first reflector and one side edge close to the test block body is 25 mm ± 0.1 mm;

[0032] The distance between the first reflector, the second reflector and the third reflector is 25 mm±0.1 mm.

[0033] Preferably, the diameter of the fourth reflector is 1.5 mm ± 0.1 mm, the diameter of the fifth reflector is 2 mm ± 0.1 mm, and the diameter of the sixth reflector is 3 mm ± 0.1 mm;

[0034] The distance between the fourth reflector and the adjacent side of the test block body is 125 mm ± 0.1 mm;

[0035] The distances between the fourth reflector, the fifth reflector and the sixth reflector are 25 mm±0.1 mm.

[0036] Preferably, the depth of the preliminary corrosion-resistant layer is 3 mm ± 0.1 mm.

[0037] The present invention provides a method for detecting defects on the fine turning surface of the cladding corrosion-resistant layer on a pump product and a simulated defect comparison test block, which can effectively detect defects on the fine turning surface in advance, prejudge and process the defects in advance, ensure the first-time pass rate of surface flaw detection on the fine turning surface, reduce the time cost of reprocessing caused by the rework of the fine turning surface, waste of labor costs and the impact on normal production scheduling and delivery period, and more importantly, avoid the impact of repair welding on critical dimensions with higher precision, thereby ensuring product quality. At the same time, the simulated defect comparison test block of the present invention can effectively compare the actual state of defects at a certain depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic flow chart of the method for detecting defects on a fine turning surface of the present invention;

[0039] Figure 2 It is a structural schematic diagram of a simulated defect comparison test block of the present invention;

[0040] Figure 3 yes Figure 2 Schematic diagram of top view;

[0041] Figure 4 It is a schematic diagram of the scanning direction in Example 1 of the method for detecting defects on fine turning surfaces of the present invention. DETAILED DESCRIPTION

[0042] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0043] Combination Figure 1 As shown, the present invention provides a method for detecting defects on the fine turning surface of a cladding corrosion-resistant layer on a pump product, comprising the following steps:

[0044] S1, evaluate the defects to be detected and make simulated defect comparison test blocks;

[0045] S2, formulate the testing process plan;

[0046] S3, testing equipment calibration;

[0047] S4, detection implementation and recording of all relevant signals;

[0048] S5, assessment and judgment of defects;

[0049] S6, repair of defects exceeding the standard;

[0050] S7, re-inspect according to the original process.

[0051] The above step S1 specifically includes:

[0052] Prepare in advance the types and sizes of defects that are not allowed to exist on the finished surface of the weld overlay layer for evaluation, and establish the allowable range of defects;

[0053] According to the qualified range specified in the standard, design and produce simulated defect comparison test blocks.

[0054] The above step S2 specifically includes:

[0055] The test plate is welded according to the same process parameters, and the simulated defect reflector is processed. The defect depth is consistent with the fine turning surface of the cladding layer.

[0056] In the above step S3, the selection of detection equipment and probe must meet the detection requirements, and parameters such as detection sensitivity, scanning direction, and scanning speed must be set.

[0057] The calibration is carried out on the simulated defect comparison test block according to the set process parameters.

[0058] The above step S4 specifically includes:

[0059] Carry out a comprehensive inspection of the workpiece according to the predetermined inspection plan, record all defect signals and mark the defect locations on the workpiece surface.

[0060] The above step S5 specifically includes:

[0061] Evaluate whether all detected defects are exposed on the machined surface after fine turning, and whether the exposed defects are within the qualified range. Record and track qualified defects, and mark the corresponding size information for defects that exceed the standard to provide data for rework.

[0062] Combination Figure 2 and Figure 3 As shown, the present invention further provides a simulated defect comparison test block for the fine turning surface defect detection method of the present invention, including a test block body 10.

[0063] The test block body 10 is made into a rectangular body by using the same material, the same welding process and the same heat treatment method.

[0064] The upper surface of the test block body 10 is provided with a corrosion-resistant layer 11 of a pre-test depth.

[0065] A first reflector 12 , a second reflector 13 , and a third reflector 14 are sequentially arranged on the left side of the center line of the test block body 10 from left to right; a fourth reflector 15 , a fifth reflector 16 , and a sixth reflector 17 are sequentially arranged on the right side of the center line of the test block body 10 from left to right.

[0066] The first reflector 12 and the fourth reflector 15 are used for sensitivity calibration, and the second reflector 13, the third reflector 14, the fifth reflector 16 and the sixth reflector 17 are used for defect size comparison.

[0067] Effective calibration of the specific depth of the corrosion-resistant layer 11 and more accurate defect comparison avoids errors caused by manual adjustments. The accuracy of the detection data is ensured through defect comparison, the detection efficiency is improved, and the error rate of human error in defect determination is reduced.

[0068] The first reflector 12, the second reflector 13, and the third reflector 14 are all arranged as cylindrical holes with hemispherical bottoms. The first reflector 12 is used for calibrating the probe detection sensitivity of the dual-crystal longitudinal wave 0° probe, and can also be used for actual detection defect size comparison; the second reflector 13 and the third reflector 14 are used for defect comparison of the actual size of the defect signal during the detection process.

[0069] The fourth reflector 15, the fifth reflector 16, and the sixth reflector 17 are all arranged as cylindrical holes with flat bottoms. The fourth reflector 15 is used for calibrating the probe detection sensitivity of the double-crystal longitudinal wave 70° oblique probe, and can also be used for actual detection defect size comparison; the fifth reflector 16 and the sixth reflector 17 are used for defect comparison of the actual size of the defect signal during the detection process.

[0070] The diameter of the first reflector 12 is 1.5 mm±0.1 mm, the diameter of the second reflector 13 is 2 mm±0.1 mm, and the diameter of the third reflector 14 is 3 mm±0.1 mm.

[0071] The distance between the first reflector 12 and the left side of the test block body 10 is 25 mm±0.1 mm.

[0072] The distance between the first reflector 12, the second reflector 13 and the third reflector 14 is 25 mm±0.1 mm.

[0073] The diameter of the fourth reflector 15 is 1.5 mm±0.1 mm, the diameter of the fifth reflector 16 is 2 mm±0.1 mm, and the diameter of the sixth reflector 17 is 3 mm±0.1 mm.

[0074] The distance between the fourth reflector 15 and the left side of the test block body 10 is 125 mm ± 0.1 mm;

[0075] The distance between the fourth reflector 15 , the fifth reflector 16 , and the sixth reflector 17 is 25 mm±0.1 mm.

[0076] The thickness of the corrosion-resistant layer 11 is 3 mm±0.1 mm.

[0077] Example 1

[0078] This embodiment 1 provides a method for detecting defects on the fine turning surface of a cladding corrosion-resistant layer on a pump product.

[0079] First, the types and sizes of pre-detected defects are evaluated according to the defect conditions required by the surface quality, and a defect simulation comparison test block is made, which includes a cylindrical hole with a hemispherical bottom on the fine-turned surface (located on the vertical surface of the test block), which are the first reflector 12, the second reflector 13, and the third reflector 14; and includes a cylindrical hole with a flat bottom (located at the horizontal position of the test block), which are the fourth reflector 15, the fifth reflector 16, and the sixth reflector 17. The depths of the six simulated defect reflectors are consistent with the size of the position of the fine-turned surface.

[0080] Secondly, the equipment and probe performance are debugged according to the technical parameters of the specified detection scheme, and a dual-crystal straight probe with a suitable focus is selected to perform calibration on a defect simulation comparison test block using the first reflector 12, and the workpiece is scanned with this hole as the reference sensitivity (see the scanning direction for details). Figure 4 ), find the defect signal and combine it with the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, static echo waveform and dynamic echo waveform to determine the defect nature, and then use the first reflector 12, the second reflector 13 and the third reflector 14 on the defect simulation comparison test block for comparison, and record the detection data; debug the equipment and probe performance according to the technical parameters of the specified detection scheme, select a dual-crystal longitudinal wave oblique probe with a suitable focus to calibrate it on the defect simulation comparison test block with the fourth reflector 15, and use this hole as the reference sensitivity to scan the workpiece (see the scanning direction for details). Figure 4 ), the defect signal is found to be combined with the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, echo static waveform and echo dynamic waveform to determine the nature of the defect, and then the fourth reflector 15, the fifth reflector 16 and the sixth reflector 17 on the defect simulation comparison test block are compared and the detection data are recorded.

[0081] After the inspection, all defect data are analyzed and evaluated, the depth and plane positions of all defects on the fine-turned surface are marked, and the defects that can be removed during the fine-turning process and even those exposed on the fine-turned surface are recorded and tracked.

[0082] Then, repair the defects in advance.

[0083] Finally, re-inspect according to the original testing process.

[0084] In this embodiment 1, the ultrasonic detection adopts the pulse echo method, which uses the acoustic pulse emitted by the acoustic wave to reflect the received signal (indicating the defect) from the part where the acoustic impedance changes. Longitudinal wave vertical flaw detection and transverse wave oblique incidence flaw detection are the two main flaw detection methods in ultrasonic flaw detection. The two methods complement each other. Longitudinal waves are easy to find defects that are parallel to the scanning surface or slightly inclined, while oblique transverse waves are easy to find defects that are at a certain angle or have a large inclination to the scanning surface.

[0085] Using the principle and characteristics of the ultrasonic testing echo method, a dual-crystal longitudinal wave oblique probe and a dual-crystal straight probe are used to identify and judge the inside of the cladding layer (the nature of the defect is determined by the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, echo static waveform and echo dynamic waveform), to discover and deal with defects on the fine turning surface in advance, and improve the first-time pass rate of penetration testing after fine turning. The processed test block simulates real defects, the spherical hole simulates volume defects (such as pores, slag inclusions), and the transverse hole simulates surface defects (such as unmelted, cracks). At this time, the block provides a simulation comparison sample for the fine turning surface. In addition, it is found in actual work that the dual crystal longitudinal wave oblique probe can not only detect the internal defects of the cladding layer, but also detect the reheating cracks in the base material under the cladding layer and the dangerous area defects perpendicular to the surface. These defects cannot be found with the dual crystal straight probe. Therefore, although the reheating cracks in the base material under the cladding layer are very rare with the improvement and development of materials and welding processes, it cannot be ruled out that some raw materials are of poor quality, or the welding process is unreasonable, or the welding operation is not standardized, resulting in dangerous defects perpendicular to the surface of the cladding layer. In summary, in order to ensure the quality of the cladding layer, combined with the ultrasonic detection results, the identification signal is analyzed and processed (the nature of the defect is determined by the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, echo static waveform and echo dynamic waveform), which can effectively solve the larger defects on the fine turning surface that exceed the final penetration inspection standard.

[0086] Example 2

[0087] This embodiment 2 provides a simulated defect comparison test block for the fine turning surface defect detection method of embodiment 1, including a test block body 10.

[0088] The cylindrical holes with hemispherical bottoms on the fine-turned surface of the test block body 10 (located on the vertical surface of the test block) are respectively the first reflector 12, the second reflector 13, and the third reflector 14; it includes cylindrical holes with flat bottoms (located at the horizontal position of the test block), which are respectively the fourth reflector 15, the fifth reflector 16, and the sixth reflector 17. The depths of the six simulated defect reflectors are consistent with the size of the position of the fine-turned surface.

[0089] The first reflector 12, the second reflector 13, and the third reflector 14 are all arranged as cylindrical holes with hemispherical bottoms. The first reflector 12 is used for calibrating the probe detection sensitivity of the dual-crystal longitudinal wave 0° probe, and can also be used for actual detection defect size comparison; the second reflector 13 and the third reflector 14 are used for defect comparison of the actual size of the defect signal during the detection process.

[0090] The fourth reflector 15, the fifth reflector 16, and the sixth reflector 17 are all arranged as cylindrical holes with flat bottoms. The fourth reflector 15 is used for calibrating the probe detection sensitivity of the double-crystal longitudinal wave 70° oblique probe, and can also be used for actual detection defect size comparison; the fifth reflector 16 and the sixth reflector 17 are used for defect comparison of the actual size of the defect signal during the detection process.

[0091] Debug the equipment and probe performance according to the technical parameters of the specified detection scheme, select a double crystal straight probe with a suitable focus, and use the first reflector 12 to calibrate on the defect simulation comparison test block, and use this hole as the reference sensitivity to scan the workpiece (see the scanning direction for details). Figure 4 ), find the defect signal and combine it with the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, static echo waveform and dynamic echo waveform to determine the defect nature, and then use the first reflector 12, the second reflector 13 and the third reflector 14 on the defect simulation comparison test block for comparison, and record the detection data; debug the equipment and probe performance according to the technical parameters of the specified detection scheme, select a dual-crystal longitudinal wave oblique probe with a suitable focus to calibrate it on the defect simulation comparison test block with the fourth reflector 15, and use this hole as the reference sensitivity to scan the workpiece (see the scanning direction for details). Figure 4 ), the defect signal is found to be combined with the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, echo static waveform and echo dynamic waveform to determine the nature of the defect, and then the fourth reflector 15, the fifth reflector 16 and the sixth reflector 17 on the defect simulation comparison test block are compared and the detection data are recorded.

[0092] After the inspection, all defect data are analyzed and evaluated, and the depth and plane positions of all defects on the fine-turning surface are marked. Defects that can be removed during the fine-turning process and defects that are exposed on the fine-turning surface are recorded and tracked. Then, defects are repaired in advance.

[0093] In this embodiment 2, a dual-crystal longitudinal wave oblique probe and a dual-crystal straight probe are used to identify and judge the inside of the cladding layer (the defect properties are determined according to the following parameters: welding process, geometric position of defects, maximum echo height, reflection direction, echo static waveform and echo dynamic waveform), so as to discover and treat defects located on the fine turning surface in advance and improve the first-time qualified rate of penetration detection after fine turning. The processed test block simulates real defects, the spherical hole simulates volume defects (such as pores and slag inclusions), and the cylindrical hole simulates surface defects (such as unmelted and cracks). At this time, the block provides a simulation comparison sample for the fine turning surface. In addition, it is found in actual work that the dual-crystal longitudinal wave oblique probe can not only detect internal defects of the cladding layer, but also detect reheating cracks in the parent material under the cladding layer and area-shaped dangerous defects perpendicular to the surface. These defects cannot be found by the dual-crystal straight probe. Therefore, although with the improvement and development of materials and welding processes, reheating cracks in the parent material under the cladding layer are very rare, it cannot be ruled out that some raw materials are of poor quality, or the welding process is unreasonable, or the welding operation is not standardized, resulting in dangerous defects perpendicular to the surface of the cladding layer.

[0094] In summary, in order to ensure the quality of the corrosion-resistant layer, defect simulation test blocks are used in combination with ultrasonic detection results to analyze and process the identification signals (the nature of the defect is determined by the following parameters: welding process, geometric position of the defect, maximum echo height, reflection direction, echo static waveform and echo dynamic waveform), which can effectively solve the larger defects on the fine turning surface that exceed the final penetration inspection standards.

[0095] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for detecting defects in the fine turning surface of a cladding corrosion-resistant layer on a pump product, characterized in that: The following steps are involved: S1, evaluate the defects to be detected and make simulated defect comparison test blocks; S2, formulate the testing process plan; S3, testing equipment calibration; S4, detection implementation and recording of all relevant signals; S5, assessment and judgment of defects; S6, repair of defects exceeding the standard; S7, re-inspect according to the original process.

2. The method for detecting defects in the fine turning surface of the cladding corrosion-resistant layer on a pump product according to claim 1 is characterized in that: The step S1 specifically includes: Prepare in advance the types and sizes of defects that are not allowed to exist on the finished surface of the weld overlay layer for evaluation, and establish the allowable range of defects; According to the qualified range specified in the standard, the simulated defect comparison test block is designed and manufactured.

3. The method for detecting defects in the fine turning surface of the cladding corrosion-resistant layer on a pump product according to claim 1, characterized in that: The step S2 specifically includes: The test plate is welded according to the same process parameters, and the simulated defect reflector is processed. The defect depth is consistent with the fine turning surface of the cladding layer.

4. The method for detecting defects in the fine turning surface of the cladding corrosion-resistant layer on a pump product according to claim 1, characterized in that: In step S3, the detection equipment calibration includes detection sensitivity, scanning direction, and scanning speed.

5. The method for detecting defects of the fine turning surface of the cladding corrosion-resistant layer on the pump product according to claim 1 is characterized in that: The step S5 specifically includes: Evaluate whether all detected defects are exposed on the machined surface after fine turning, and whether the exposed defects are within the qualified range. Record and track qualified defects, and mark the corresponding size information for defects that exceed the standard.

6. A simulated defect comparison test block for the fine turning surface defect detection method according to any one of claims 1 to 5, characterized in that: Including test block body; The test block body is configured as a rectangular body; The test block body is provided with a corrosion-resistant layer made of the same material and the same process as the pre-inspected workpiece; The test block body is provided with a first reflector, a second reflector, a third reflector, a fourth reflector, a fifth reflector and a sixth reflector; The first reflector, the second reflector, and the third reflector are located on one side of the center line of the test block body, and the fourth reflector, the fifth reflector, and the sixth reflector are located on the other side of the center line of the test block body.

7. The simulated defect comparison test block according to claim 6, characterized in that: The first reflector, the second reflector and the third reflector are all configured as cylindrical holes with hemispherical bottoms; The fourth reflector, the fifth reflector and the sixth reflector are all configured as cylindrical holes with a flat bottom.

8. The simulated defect comparison test block according to claim 6, characterized in that: The diameter of the first reflector is 1.5 mm ± 0.1 mm, the diameter of the second reflector is 2 mm ± 0.1 mm, and the diameter of the third reflector is 3 mm ± 0.1 mm; The distance between the first reflector and one side edge close to the test block body is 25 mm ± 0.1 mm; The distance between the first reflector, the second reflector and the third reflector is 25 mm±0.1 mm.

9. The simulated defect comparison test block according to claim 8, characterized in that: The diameter of the fourth reflector is 1.5 mm ± 0.1 mm, the diameter of the fifth reflector is 2 mm ± 0.1 mm, and the diameter of the sixth reflector is 3 mm ± 0.1 mm; The distance between the fourth reflector and the adjacent side of the test block body is 125 mm ± 0.1 mm; The distances between the fourth reflector, the fifth reflector and the sixth reflector are 25 mm±0.1 mm.

10. The simulated defect comparison test block according to claim 6, characterized in that: The thickness of the corrosion-resistant layer is 3 mm ± 0.1 mm.

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