Ultrasonic detection system and detection method for thick-walled pipes

Abstract

The present invention relates to the field of ultrasonic detection technology, and discloses an ultrasonic detection system for thick-walled pipes, including a shear wave comparison test block, a shear wave detection probe, a longitudinal wave comparison test block, and a longitudinal wave detection probe; U-shaped grooves are opened on the inner wall and the outer wall of the shear wave comparison test block; a circular hole is opened at one end of the longitudinal wave comparison test block; the longitudinal wave detection probe adopts a double crystal probe; the shear wave detection probe is a shear wave probe with a curvature wedge, and the curvature radius of the curvature wedge matches the radius of the pipe to be detected. The present invention also discloses a detection method, which adds longitudinal wave flaw detection on the basis of shear waves, thereby improving the detection sensitivity and resolution of such thick-walled pipes; the detection method in which the pipe is in direct contact with the probe can effectively reduce the scattering and absorption of sound waves in water, and improve the sensitivity of pipe detection, because there is no water layer attenuation between the probe and the pipe, and is particularly suitable for high-sensitivity detection of such large-sized pipes.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic detection, and in particular to an ultrasonic detection system and a detection method for thick-walled pipes. Background Art

[0002] Since there were no domestic large-size pipes (maximum diameter Ф175mm) manufacturers in the early stage of the air duct of a certain aircraft engine, the raw materials were supplied in the form of forgings. In recent years, domestic manufacturers have been able to produce large-size pipes. In order to reduce raw material consumption and production costs, the raw materials of the air duct of a certain aircraft engine have been changed from bars to thick-walled TC11 titanium alloy pipes for direct processing and forming. The processing process of thick-walled pipes is different from the forming mechanism of bars. Stretching and rolling cause radial and axial stresses in the material, and the orientation of defects is more complicated than that of bars. However, the wall thickness of general pipes is thinner. The ultrasonic detection of thin-walled pipes generally uses shear wave detection, which is not suitable for thick-walled pipe detection. Therefore, in order to comprehensively evaluate the product quality of thick-walled pipes instead of forgings to produce air ducts, it is necessary to develop appropriate ultrasonic detection methods for such thick-walled pipes to meet the quality control requirements of the product. Summary of the invention

[0003] The purpose of the present invention is to provide an ultrasonic detection system and detection method for thick-walled pipes, which solves the problem that the existing ultrasonic detection method cannot be applied to the detection of thick-walled pipes.

[0004] The present invention is achieved through the following technical solutions:

[0005] An ultrasonic testing system for thick-walled pipes, comprising a shear wave testing comparison test block, a shear wave testing probe, a longitudinal wave testing comparison test block and a longitudinal wave testing probe;

[0006] U-shaped grooves are opened on the inner and outer walls of the shear wave test comparison block;

[0007] A circular hole is opened at one end of the longitudinal wave detection comparison test block;

[0008] The longitudinal wave detection probe adopts a dual crystal probe;

[0009] The shear wave detection probe is a shear wave probe with a curvature wedge, and the curvature radius of the curvature wedge matches the radius of the pipe to be detected.

[0010] Furthermore, the curvature wedge is made of plexiglass.

[0011] Furthermore, the chip size of the longitudinal wave detection probe is 10 mm.

[0012] Furthermore, when longitudinal wave focusing detection is performed under the surface of the pipe to be detected, the detection focus depth is 15 mm.

[0013] Furthermore, the shear wave detection comparison block is a cylindrical block, and the longitudinal wave detection comparison block is a cylindrical block.

[0014] Furthermore, the depth of the U-shaped groove is no more than 1.5% of the wall thickness of the shear wave detection comparison test block, the width of the U-shaped groove is no more than twice the depth of the U-shaped groove, and the length is 10 mm.

[0015] Furthermore, the diameter of the circular hole is Φ0.8 mm, and the hole depth is 1.5 mm-32 mm.

[0016] The present invention also discloses an ultrasonic detection method for thick-walled pipes by the ultrasonic detection system for thick-walled pipes, comprising the following steps:

[0017] S1. Shear wave detection: The incident angle of the detection sound wave is 20°;

[0018] S2, longitudinal wave detection:

[0019] 2.1. Use the longitudinal wave detection probe to adjust the reflection signal of the circular hole in the longitudinal wave detection comparison test block to 80% of the height of the fluorescent screen;

[0020] 2.2. After increasing by 2-4dB, and ensuring that the noise signal does not exceed 20% of the height, perform longitudinal wave detection on the pipe along the circumference and record any abnormal signals found;

[0021] 2.3 After the scanning is completed, recheck the sensitivity to determine whether the circular hole in the longitudinal wave test block is clearly visible at the specified sensitivity and the height is not less than 80%, otherwise the longitudinal wave test should be re-implemented;

[0022] 2.4 Comprehensively evaluate the results of longitudinal and transverse wave inspections of pipes. If any signal exceeding the standard is found, the pipe will be rejected; otherwise, it will be deemed qualified.

[0023] Furthermore, during shear wave detection, the parameters of the shear wave detection probe are: the probe frequency is selected as 5 MHz, the chip thickness is 20 mm, and the K1 probe is selected so that the refraction angle of the shear wave propagating in the pipe is 45°.

[0024] Furthermore, during longitudinal wave detection, the parameters of the longitudinal wave detection probe are: the probe frequency is selected as 5 MHz, the chip thickness is 10 mm, and the focus position is selected as F15.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention discloses an ultrasonic detection system for thick-walled pipes, including a shear wave comparison test block, a shear wave detection probe, a longitudinal wave comparison test block and a longitudinal wave detection probe; defects extending radially along the pipe are detected by the shear wave comparison test block, defects with a large inclination angle to the detection surface are detected by the shear wave detection probe, defects extending axially along the pipe are detected by the longitudinal wave comparison test block, and defects parallel to the detection surface are detected by the longitudinal wave detection probe; U-shaped grooves are provided on the inner and outer walls of the shear wave comparison test block to improve energy reflection and detection sensitivity; a dual crystal probe is used to detect flaws along the outer surface of the pipe, which can reduce the detection blind area, improve the defect detection rate, and accurately locate the defects. The present invention adds a longitudinal wave detection comparison test block and a longitudinal wave detection probe, adds longitudinal wave flaw detection on the basis of shear waves, and improves the detection sensitivity and resolution of such thick-walled pipes.

[0027] Furthermore, the setting of the probe chip size mainly considers the detection range or depth. Generally, the chip size used for longitudinal wave detection is 14mm-20mm. However, for this type of thick-walled pipe, due to the large curvature radius, a small chip probe is required to reduce sound wave scattering and energy loss. However, a chip that is too small will reduce the emission energy. After comprehensive consideration, a 10mm chip is selected.

[0028] Furthermore, since this type of thin-walled pipe is characterized by a small processing allowance of only about 2mm and a large detection thickness of about 32mm at most, while ensuring detection sensitivity and taking detection efficiency into consideration, the subsurface focused contact method detection mode is selected with a detection focus depth of 15mm to ensure that the detection resolution meets the requirements.

[0029] The present invention also discloses an ultrasonic detection method for thick-walled pipes, which mainly includes two detection methods: transverse wave detection and longitudinal wave focusing detection under the longitudinal wave surface. Relevant detection tests are carried out for such thick-walled pipes, which can make the depth of artificial defects on the inner and outer walls of pipes with an outer diameter of 175mm and a wall thickness of 32mm not less than 0.4mm during transverse wave detection, and the signal-to-noise ratio is not less than 12dB under the premise that the sensitivity of longitudinal wave detection of curved surface pipes is 0.8mm. Contact detection is a detection method in which the pipe and the probe are in direct contact. Because there is no water layer attenuation between the probe and the pipe, the scattering and absorption of sound waves in water can be effectively reduced, and the sensitivity of pipe detection can be improved. It is especially suitable for high-sensitivity detection of such large-sized pipes. If water immersion detection is used, due to the large wall thickness of the pipe, it is easy for the secondary interface echo to enter the primary bottom wave, which will cause greater interference to the detection of defects and cause misjudgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of the longitudinal wave comparison test block;

[0031] Figure 2 Axial U-shaped groove on the outer wall of the comparison test block for shear wave detection

[0032] Figure 3 Axial U-shaped groove on the inner wall of the comparison test block for shear wave detection;

[0033] Figure 4 It is a structural schematic diagram of a shear wave detection probe;

[0034] Figure 5 When using a conventional longitudinal wave straight probe for longitudinal wave detection, the schematic diagram of the circular hole near the surface cannot be found.

[0035] Figure 6 This is a schematic diagram of defects found after using a dual crystal probe during longitudinal wave testing;

[0036] Figure 7 The schematic diagram of using shear wave probe to detect defects on the outer wall of pipe after the defects are found;

[0037] Figure 8 Schematic diagram of the use of shear wave probe to detect defects on the inner wall of the pipe after the defects are found.

[0038] Among them, 1 is a longitudinal wave comparison test block, 11 is a circular hole, 2 is a transverse wave comparison test block, 21 is a U-shaped groove, 3 is a curvature wedge, 4 is a probe wafer, and 5 is a data line. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0040] Ultrasonic testing is mainly divided into direct beam method (longitudinal wave) and oblique beam method (transverse wave). Longitudinal waves are suitable for detecting defects parallel to the test surface, while transverse waves are used to detect defects with a large inclination angle to the test surface.

[0041] There are two main directions of defects in pipes: axial and radial. Axial defects are approximately parallel to the pipe axis, while radial defects are perpendicular to the pipe axis, and axial defects are more harmful. Generally, due to the processing technology, the defects produced in pipes are mainly axial extension cracks.

[0042] The ultrasonic oblique incident shear wave method has high sensitivity for axial defect detection and can detect and identify defects on the inner and outer walls. According to the law of refraction and reflection of ultrasound, when inspecting pipes, a suitable incident angle must be selected to ensure that there are only shear waves in the pipe wall. When the ultrasonic wave is obliquely incident on the pipe wall at a certain angle, the shear wave advances along the W route at a certain angle. If no defects are encountered on the forward route, the probe will not receive the echo signal, indicating that the inner and outer pipe walls are intact; when defects appear on the forward path of the sound wave, a reflected echo will be generated, and the echo will propagate back to the probe in the opposite path. When the probe receives the reflected echo, it means that there are defects in the pipe or on the inner and outer walls. Therefore, the inspection of thick-walled pipes requires the addition of longitudinal wave flaw detection on the basis of shear wave flaw detection.

[0043] Determination of detection parameters:

[0044] 1.1 Comparison test block

[0045] The comparison test block is an important basis for adjusting the detection sensitivity and judging whether the defects exceed the standard. The comparison test block is made of the same material as the inspected piece or has similar acoustic properties. It is made by processing artificial standard defects on the selected sample according to relevant technical requirements.

[0046] When testing longitudinal waves, a set of distance amplitude test blocks with the same aperture and different buried depths are needed to adjust the sensitivity. Combined with the pipe specifications and requirements, the diameter of the circular hole 11 buried in the longitudinal wave comparison test block 1 is Φ0.8mm, and the hole depth includes 1.5mm-32mm. Figure 1 shown.

[0047] During shear wave testing, the comparison test block is made of the same specifications as the pipe to be tested, and artificial grooves are made on the inner and outer pipe walls to adjust the instrument, incident angle, probe and other parameters. Figure 2 , Figure 3 And as shown in Table 1.

[0048] Pipe defects are generally detected by rectangular or V-shaped grooves, which are easy to process. However, these two artificial grooves have low energy reflectivity, and thick-walled pipes mainly consider energy loss. Therefore, the present invention modifies the shear wave groove into a U-shaped groove 21 to improve energy reflection and detection sensitivity.

[0049] Table 1 Shear wave comparison test block artificial groove

[0050]

[0051] 1.2 Probe

[0052] 1.2.1 Ultrasonic longitudinal wave testing of thick-walled pipes

[0053] The most commonly used ultrasonic contact method detection is the contact type longitudinal wave straight probe and the dual crystal probe, and the main detection areas of the two are different. The straight probe has a deeper detection depth, but a larger near-surface blind area; the dual crystal probe has a strong ability to detect near-surface defects, a smaller blind area, but a shallower detection depth. Since the detection area is deeper when the bar is inspected along the outer surface, a longitudinal wave straight probe is used to detect axial defects parallel to the detection surface. The maximum wall thickness of TC11 titanium alloy pipes is 32mm, so it is not suitable to use conventional straight probes. It is suitable to use dual crystal probes to detect flaws along the outer surface of the pipe.

[0054] The main parameters that affect the performance of the dual crystal probe are frequency, crystal size and the range of the acoustic beam convergence area (focus position). The optimal probe parameters were selected by performing flaw detection experiments on the pipe round hole 11 comparison test block, as shown in Table 2.

[0055] Table 2 Parameters of ultrasonic longitudinal wave detection probe for pipes

[0056]

[0057] The longitudinal wave contact method is selected for this type of pipe testing, which is the first time in the industry. It is mainly based on the forming characteristics of thick-walled pipes. At the same time, the processing allowance during forming is only 2mm, which is a blank pipe with extremely small allowance. In addition, the aviation system has high requirements for pipe testing. Based on the 0.8mm detection sensitivity requirement for titanium alloy, when considering the use of subsurface longitudinal wave focusing detection, the detection focus depth is set to 15mm. The setting of the probe chip 4 size mainly considers the detection range or depth. Generally, the chip size used for longitudinal wave detection is 14mm-20mm. However, this type of thick-walled pipe has a large curvature radius. In order to reduce sound wave scattering and energy loss, a small chip probe is required. However, a chip that is too small will reduce the size of the emission energy. After comprehensive consideration, a 10mm chip is selected.

[0058] When the subsurface longitudinal wave focusing test is performed, the detection focus depth is 15mm. Since the thin-walled pipes are characterized by small processing allowance, only about 2mm, and large detection thickness, about 32mm at most, the subsurface focusing contact method detection mode is selected to ensure that the detection resolution meets the requirements while ensuring the detection sensitivity and taking into account the detection efficiency.

[0059] 1.2.2 Ultrasonic shear wave testing of thick-walled pipes

[0060] The surface of ordinary shear wave oblique probe is smooth and is mainly used to detect workpieces with parallel surfaces. For pipes, the surface curvature is large, and ordinary oblique probes are not well coupled with the workpiece surface, resulting in poor detection effect. The shear wave wedge probe includes a wedge, a probe chip 4, and a data line 5. Therefore, it is necessary to design and manufacture a wedge with the same curvature as the thick-walled pipe, see Figure 4The main component of the curvature wedge 3 is organic glass. The advantages of the shear wave probe with the curvature wedge 3 are: ① good contact with the pipe surface and good coupling effect; ② easy to operate, high detection efficiency, stable defect detection ability, less human interference factors, and more accurate detection results; ③ under the protection of the organic wedge, the probe does not directly contact the pipe, with less wear, longer service life of the probe, and cost saving.

[0061] Because all probe wafers 4 can only emit longitudinal waves, shear waves are generated through waveform conversion of the wedge block with curvature 3. When testing thick-walled titanium alloy pipes, the part where the wedge block connects to the wafer has a certain inclination angle, which is the incident angle of the sound wave. The design of this angle must ensure that the inner and outer wall grooves in the shear wave comparison test block 2 can be found, and the sensitivity difference of the artificial defects of the inner and outer walls is not greater than 2dB. By designing shear wave wedge probes with different inclination angles, a large number of tests finally determined that the angle of the wedge block, that is, the incident angle of the detection sound wave, is 20°.

[0062] The shear wave detection of pipes usually adopts the oblique beam method. The ultrasonic wave emitted by the chip 4 reaches the outer surface of the pipe through a wedge with a certain inclination angle, and then reaches the inner wall of the pipe after refraction and waveform conversion. When selecting the parameters of the shear wave detection probe, in addition to the chip size and frequency, the K value of the probe is particularly important. The K value determines the size of the refraction angle in the pipe, which directly affects whether the ultrasonic shear wave beam can reach the inner wall of the pipe to ensure the detection of defects.

[0063] Through experiments, it was determined that the shear wave detection method for pipes is axial scanning, such as Figure 6 As shown. Under the premise of ensuring the effective incidence and scanning stability of the probe, the optimal scanning parameters are selected: ① Under the premise of ensuring a good detection signal-to-noise ratio, the probe frequency is selected as 5MHz, so that the scanning sound beam has higher energy; ② The chip thickness is selected as 20mm to ensure the detection efficiency; ③ Select the K1 probe to make the refraction angle of the transverse wave propagating in the pipe 45°, which improves the accuracy of defect positioning.

[0064] like Figure 6 As shown in the figure, under the above scanning parameters, the use of a probe with a wedge block can detect defect signals on the outer wall of the pipe comparison test block with high sensitivity.

[0065] The ultrasonic detection method for thick-walled pipes based on the ultrasonic detection system for thick-walled pipes comprises the following steps:

[0066] S1. Shear wave detection:

[0067] 1.1. Place the shear wave detection probe on the shear wave comparison test block 2, move the shear wave detection probe on the shear wave comparison test block 2, find the maximum value of the internal groove damage of the shear wave comparison test block 2, adjust the gain of the flaw detector, and adjust the maximum value of the internal groove damage of the shear wave comparison test block 2 to 80% of the full scale of the fluorescent screen of the flaw detector;

[0068] 1.2. After increasing the gain of the flaw detector by 3-5dB and ensuring that the noise signal does not exceed 40% of the height, perform a shear wave scan on the circumferential surface of the pipe. The sound wave enters the pipe to be tested along the radial direction and records the abnormal signals found;

[0069] 1.3. After the scanning is completed, recheck the sensitivity to determine whether the groove damage of the shear wave comparison test block 2 is clearly visible at the specified sensitivity, and whether the display signal height of the artificial groove in the shear wave comparison test block 2 is not less than 80%, otherwise the shear wave test should be re-implemented;

[0070] S2, longitudinal wave detection:

[0071] 2.1. Place the longitudinal wave detection probe on the longitudinal wave comparison test block 1, move the longitudinal wave detection probe to find the highest value of the reflected signal of the circular hole 11 inside the longitudinal wave comparison test block 1, adjust the gain of the flaw detector, and adjust the highest value to 80% of the full scale of the fluorescent screen.

[0072] 2.2. After increasing by 2-4dB, and ensuring that the noise signal does not exceed 20% of the height, perform longitudinal wave detection on the pipe along the circumference and record any abnormal signals found;

[0073] 2.3. After the scanning is completed, recheck the sensitivity to determine whether the circular hole 11 in the longitudinal wave comparison test block 1 is clearly visible at the specified sensitivity, and whether the height of the reflected signal of the circular hole 11 inside the longitudinal wave comparison test block 1 is not less than 80%, otherwise the longitudinal wave detection should be re-implemented;

[0074] 2.4. Comprehensively evaluate the results of longitudinal and transverse wave inspections of pipes. If any signal exceeding the standard is found, the pipe will be rejected; otherwise, it will be deemed qualified.

[0075] Test results and analysis

[0076] Longitudinal wave detection:

[0077] The thick-walled pipe is tested by ultrasonic longitudinal wave A-scan, and the relationship between the amplitude of the ultrasonic signal and the propagation time is displayed in the form of rectangular coordinates. The horizontal axis is time and the vertical axis is signal amplitude. Since the ultrasonic wave propagates in a homogeneous material and the speed of sound is constant, the propagation time can be converted into the propagation distance. Therefore, the distance between the reflection surface and the sound incident surface (the depth of the defect displayed when the longitudinal wave is vertically incident) and the size of the echo amplitude (used to determine the equivalent size of the defect) can be obtained from the A-scan image.

[0078] like Figure 5 As shown in the figure, a conventional straight probe is used to scan the longitudinal wave along the outer wall of the pipe. Due to the large blind area of ​​the probe itself, the defect signal cannot be found. After the dual crystal probe is used for detection, the detection sensitivity is high, the detection blind area is small, the near-surface resolution is good, and the ability to detect defects in the pipe wall is strong, such as Figure 6 shown.

[0079] Shear wave detection:

[0080] like Figure 7 and 8 As shown, after using a shear wave wedge probe with the same curvature as the pipe, the pipe is scanned axially with shear waves. The defect display sensitivity is high, the detection results are more accurate, and the detection quality is guaranteed.

[0081] The designed shear wave comparison test block 2 is used to adjust the detection sensitivity, determine the detection frequency, chip size and incident angle, etc. When the conventional titanium alloy pipe is tested by the contact method shear wave, the probe frequency is generally 10MHz. Thick-walled titanium alloy pipes are affected by their own material properties, so 5MHz is suitable to improve the signal-to-noise ratio and resolution. The setting of the probe chip 4 size mainly considers the detection range or depth. The chip size used for general pipe detection is 10mm-15mm, but this type of thick-walled pipe has a large radius of curvature. In order to increase the detection input energy, a large-size chip can be used. However, a too large chip will increase the length of the detection plant, which is not conducive to defect location. After comprehensive consideration, a chip size of 20mm is selected. The adjustment of the shear wave refraction angle is quite different from that of conventional thin-walled pipes. Conventional pipes generally use a refraction angle of 60°-65°. Due to the large detection range of thick-walled pipes, the use of large-angle refraction will seriously reduce the detection signal-to-noise ratio, resulting in large energy attenuation and large fluctuations in detection sensitivity. Considering the characteristics of titanium alloy itself, it is determined to use 45° shear wave detection.

[0082] Using the determined detection parameters, adjust the artificial defects in the test block to 80% of the full scale of the fluorescent screen. At the same time, ensure that the noise height is not less than 40%. At this time, the detection sensitivity adjustment is considered complete, and then move the probe to the thick-walled pipe parts for detection.

Claims

1. An ultrasonic detection system for thick-walled pipes, characterized in that: It comprises a shear wave comparison test block (2), a shear wave detection probe, a longitudinal wave comparison test block (1) and a longitudinal wave detection probe; U-shaped grooves (21) are formed on the inner wall and the outer wall of the shear wave comparison test block (2); A circular hole (11) is formed at one end of the longitudinal wave comparison test block (1); The longitudinal wave detection probe adopts a dual crystal probe; The shear wave detection probe is a shear wave probe with a curvature wedge (3), and the curvature radius of the curvature wedge (3) matches the radius of the pipe to be detected; The depth of the U-shaped groove (21) is not greater than 1.5% of the wall thickness of the shear wave comparison test block (2); the width of the U-shaped groove (21) is not greater than twice the depth of the U-shaped groove (21), and the length is 10 mm; The ultrasonic detection method for thick-walled pipes by the ultrasonic detection system for thick-walled pipes comprises the following steps: S1. Shear wave detection: The incident angle of the detection sound wave is 20°; S2, longitudinal wave detection: 2.

1. Use a longitudinal wave detection probe to adjust the reflection signal of the circular hole (11) in the longitudinal wave comparison test block (1) to 80% of the height of the fluorescent screen; 2.

2. After increasing by 2-4dB and ensuring that the noise signal does not exceed 20% of the height, perform longitudinal wave detection on the pipe along the circumference and record any abnormal signals found; 2.

3. After the scanning is completed, recheck the sensitivity to determine whether the circular hole (11) in the longitudinal wave comparison test block (1) is clearly visible at the specified sensitivity and the height is not less than 80%. Otherwise, the longitudinal wave test should be repeated; S3. Comprehensively evaluate the longitudinal wave and transverse wave scanning results of the pipe. If an over-standard signal is found, the pipe will be rejected, otherwise it will be deemed qualified.

2. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: The curvature wedge (3) is made of organic glass.

3. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: The chip size of the longitudinal wave detection probe is 10mm.

4. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: When longitudinal wave focusing detection is performed under the surface of the pipe to be tested, the detection focus depth is 15mm.

5. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: The transverse wave comparison test block (2) is a cylindrical block, and the longitudinal wave comparison test block (1) is a cylindrical block.

6. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: The diameter of the circular hole (11) is Φ0.8 mm, and the hole depth ranges from 1.5 mm to 32 mm.

7. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: When performing shear wave detection, the parameters of the shear wave detection probe are: the probe frequency is selected as 5MHz, the chip thickness is 20mm, and the K1 probe is selected so that the refraction angle of the shear wave propagating in the pipe is 45°.

8. The ultrasonic detection system for thick-walled pipes according to claim 1, characterized in that: During longitudinal wave detection, the parameters of the longitudinal wave detection probe are: the probe frequency is selected as 5MHz, the chip thickness is 10mm, and the focus position is selected as F15.

Images