Adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welding seam

Abstract

The invention relates to the technical field of detection, and provides a thick plate titanium alloy welding seam self-adaptive sensitivity ultrasonic detection method which comprises the following steps: designing a combined ultrasonic transducer, designing a detection system, testing and calibrating, testing a signal-to-noise ratio, scanning and evaluating. The detection system comprises a multi-channel ultrasonic detection collector, upper computer software and a combined ultrasonic transducer. Compared with the prior art, the self-adaptive sensitivity ultrasonic detection method for the thick plate titanium alloy welding seam has the advantages that the combined ultrasonic transducer is designed, thick plate titanium alloy welding seam detection and material acoustic performance evaluation are synchronously carried out, and the sound attenuation coefficient is fed back to a welding seam detection channel in real time by using upper computer software; and the detection sensitivity is adjusted in real time, so that the problem of inaccurate defect quantification caused by sensitivity difference due to non-uniform materials is solved, and accurate evaluation on the welding defects is realized.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds. Background Art

[0002] Titanium alloys have the characteristics of high specific strength and corrosion resistance, and their use in the fields of petrochemicals, nuclear power, shipbuilding and marine engineering has increased year by year. With the development of welding technology, the welding thickness of titanium alloy products is getting larger and larger. Since large-thickness butt welds are mostly used in heavy-load, high-pressure and other working conditions, and the manufacturing cost is high, it is necessary to strictly control the quality of the welded joints and accurately detect the defects exceeding the standard during the manufacturing process.

[0003] Thick plate titanium alloy welds are mostly welded using the narrow gap TIG welding method. Its typical defects have the characteristics of small geometric size and irregular spatial orientation, which makes detection very difficult. X-ray and ultrasonic methods are often used to detect internal defects in welds. Among them, although X-ray detection has the advantage of intuitive display, as the thickness of the weld increases, the quality of the X-ray line hardens, the linear attenuation coefficient decreases, the contrast and clarity of the detection image decrease, and small defects cannot be effectively identified. In addition, since X-ray detection cannot locate the true depth of the defect, there are many inconveniences during rework, so there are great limitations in its application. Therefore, in actual detection, ultrasonic detection is more often used, which has the advantages of high detection sensitivity and accurate defect location.

[0004] The patent application number CN202111394741.9 in the prior art discloses a phased array ultrasonic detection method for titanium alloy welds for submersibles, including the following steps: selection of array transducers, transducer array element testing, wedge block production, detection system program setting, signal-to-noise ratio testing, detection sensitivity calibration, scanning and evaluation. This patent is a detection scheme based on phased array ultrasonic technology. Although a double-sided array transducer is used to realize the excitation, focusing, reception and scanning of sound waves, and a fan-shaped scanning scheme is used to image and display the detection results, which can effectively improve the signal-to-noise ratio and realize the detection of titanium alloy welds for submersibles, there are still great difficulties in conventional ultrasonic detection: (1) More importantly, due to the difficulty of titanium alloy material manufacturing process and the uneven distribution of its material structure, there are great differences in acoustic properties of different parts. The sensitivity is in a state of continuous change during the detection process, and it is impossible to accurately evaluate defects; (2) As the detection thickness increases, the defect evaluation error caused by sensitivity differences becomes more prominent.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to propose an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds to solve the great difficulties that still exist in conventional ultrasonic detection in the prior art: (1) More importantly, due to the difficulty in the manufacturing process of titanium alloy materials and the uneven distribution of their material structure, there are great differences in the acoustic properties of different parts. The sensitivity is in a state of constant change during the detection process, and defects cannot be accurately assessed; (2) As the detection thickness increases, the defect evaluation error caused by the sensitivity difference becomes more prominent.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] A method for ultrasonic detection of thick plate titanium alloy welds with adaptive sensitivity The method for ultrasonic detection of thick plate titanium alloy welds with adaptive sensitivity comprises the following steps:

[0009] Step 1, design of combined ultrasonic transducer: The combined ultrasonic transducer includes a straight-incidence channel and an oblique-incidence channel, wherein the straight-incidence channel is used to evaluate the acoustic properties of the material, and the oblique-incidence channel is used to detect the titanium alloy weld. A sound insulation layer is arranged between the straight-incidence channel and the oblique-incidence channel, and a straight-incidence wafer is arranged in the straight-incidence channel, and an oblique-incidence wafer is arranged in the oblique-incidence channel. Both the straight-incidence wafer and the oblique-incidence wafer are piezoelectric composite materials, and the shape, size, and angle of the straight-incidence wafer with the horizontal direction match the shape, size, and angle of the oblique-incidence wafer with the horizontal direction. The production of the combined ultrasonic transducer shall be subjected to spectrum testing, and the center frequency of the combined ultrasonic transducer shall be within the specified range. The straight-incidence channel and the oblique-incidence channel shall be tested separately, and the center frequency of the oblique-incidence channel is f1, and the center frequency of the straight-incidence channel is f2. f1 and f2 shall meet the following requirements:

[0010]

[0011] Step 2, detection system design: The detection system includes a multi-channel ultrasonic detection collector, a host computer software and a combined ultrasonic transducer, the combined ultrasonic transducer is connected to the multi-channel ultrasonic detection collector, and the multi-channel ultrasonic detection collector is connected to the host computer software; the direct incidence channel and the oblique incidence channel are synchronously performed, and the excitation parameters and receiving parameters of the combined ultrasonic transducer for the direct incidence channel and the oblique incidence channel should be consistent; and the detection sensitivity can be adaptively adjusted and set in the host computer software, and the adaptive adjustment setting program includes the following steps:

[0012] (1) Test the initial acoustic attenuation coefficient α0 on the thick plate titanium alloy weld ultrasonic testing comparison test block;

[0013] (2) During the workpiece inspection process, the acoustic attenuation coefficient α(t) of the inspection area is tested in real time using the direct incidence channel;

[0014] (3) The ultrasonic signal obtained by the oblique incidence channel is defined as S(t), then the compensated ultrasonic signal is S(t)+2L(t')×(α(t)-α0), where L(t') is the sound path corresponding to each signal point in a single sampling period;

[0015] Step 3, test and calibration: adjust the excitation parameters of the direct-incidence channel and the oblique-incidence channel to keep the excitation parameters of the direct-incidence channel consistent with those of the oblique-incidence channel; first, calculate the acoustic attenuation coefficient based on the two bottom-surface reflection waves of the direct-incidence channel; second, test the front length and refraction angle of the oblique-incidence channel, make a distance-amplitude curve, and set the scanning sensitivity;

[0016] Step 4: Signal-to-noise ratio test: Use a tested and calibrated detection system to perform a signal-to-noise ratio test on the workpiece to be tested. To keep the test conditions consistent, randomly select at least 3 positions within the full length of the weld to be tested for testing. The signal-to-noise ratio test requirements are met when the scattered wave signal at the maximum detection sound path of the oblique incidence channel at the test position is not higher than the scanning sensitivity curve;

[0017] Step 5: Scanning and evaluation: Maintain good coupling between the combined ultrasonic transducer and the workpiece, scan the weld and evaluate abnormal reflected waves according to the procedures specified in the standard, and evaluate the level.

[0018] Furthermore, the shape, size, and angle with the horizontal direction of the direct-incidence chip match the shape, size, and angle with the horizontal direction of the oblique-incidence chip, which means that: the shapes of the direct-incidence chip and the oblique-incidence chip are both circular, the diameter range of the oblique-incidence chip is 10 to 20 mm, and the diameter of the direct-incidence chip is 10 mm; the angle between the oblique-incidence chip and the horizontal direction is 15.7° or 19.4°, and the angle between the direct-incidence chip and the horizontal direction is 0°.

[0019] Furthermore, the center frequency of the combined ultrasonic transducer in step one should be within a prescribed range, which means that the center frequency is 2 to 5 MHz.

[0020] Furthermore, the multi-channel ultrasonic detection collector has at least two independent channels, and the channels of the multi-channel ultrasonic detection collector can excite and receive signals in parallel.

[0021] Furthermore, the excitation parameters and receiving parameters of the combined ultrasonic transducer for the direct-incident channel and the oblique-incident channel in step 2 should be consistent, which means that the excitation pulse type, excitation pulse voltage, excitation pulse width, pulse repetition frequency and receiving filter of the direct-incident channel are exactly the same as the excitation pulse type, excitation pulse voltage, excitation pulse width, pulse repetition frequency and receiving filter of the oblique-incident channel.

[0022] Furthermore, in step 4, a signal-to-noise ratio test is performed on the workpiece to be inspected using the tested and calibrated detection system. Maintaining consistency in the test conditions means that the temperature difference between the comparison test block and the workpiece to be inspected is ≤19°C, and the coupling agent used should be consistent.

[0023] Furthermore, the maximum detection sound path of the test position in step 4 in the oblique incidence channel means that when the oblique incidence chip is at an angle of 15.7° with the horizontal direction, the sound path is 1.42 times the thickness of the base material; when the oblique incidence chip is at an angle of 19.4° with the horizontal direction, the sound path is 2 times the thickness of the base material.

[0024] Furthermore, the maximum detectable weld thickness is ≥160mm, the detection sensitivity can reach φ2×40mm-18dB, and the sensitivity error is ≤3dB.

[0025] The present invention proposes an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds. Compared with the prior art, the adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds of the present invention has the following beneficial effects:

[0026] 1) The present invention discloses an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds, and designs a combined ultrasonic transducer. The combined ultrasonic transducer includes a direct incidence channel and an oblique incidence channel, which realizes the simultaneous detection of thick plate titanium alloy welds and evaluation of material acoustic properties. The upper computer software is used to feed back the acoustic attenuation coefficient to the weld detection channel in real time, and the detection sensitivity is adjusted in real time, eliminating the problem of inaccurate defect quantification caused by sensitivity differences caused by material unevenness, thereby realizing accurate evaluation of welding defects.

[0027] 2) The adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds described in the present invention adopts piezoelectric composite materials as direct-incident chips and oblique-incident chips, adopts broadband signals and combines longitudinal wave oblique incidence to improve the signal-to-noise ratio of ultrasonic detection of thick plate titanium alloy welds, and can meet the purpose of high-sensitivity detection.

[0028] 3) The method for ultrasonic detection of thick plate titanium alloy welds with adaptive sensitivity described in the present invention, in addition to the adaptive sensitivity function, can also use a combined ultrasonic transducer to test in real time whether the signal-to-noise ratio of the detection area can meet the detection requirements, thereby ensuring the reliability of the detection.

[0029] 4) The present invention provides an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds. It utilizes a combined ultrasonic transducer and a multi-channel ultrasonic collector to realize real-time monitoring of the acoustic properties of thick plate titanium alloy materials and compensates them in the detection channel, thereby achieving the purpose of dynamically adjusting the detection sensitivity. The maximum detection weld thickness is not less than 160mm, the detection sensitivity can reach φ2×40mm-18dB, and the sensitivity error is not more than 3dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic cross-sectional structure diagram of a combined ultrasonic transducer for a method for ultrasonic detection of a thick plate titanium alloy weld with adaptive sensitivity according to an embodiment of the present invention;

[0031] Figure 2 A physical picture of a combined ultrasonic transducer for a method for ultrasonic detection of a thick plate titanium alloy weld with adaptive sensitivity according to an embodiment of the present invention;

[0032] Figure 3 This is a signal-to-noise ratio test diagram of a thick plate titanium alloy weld adaptive sensitivity ultrasonic detection method described in an embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1. Protective film; 2. Wedge; 31. Direct-incidence chip; 32. Oblique-incidence chip; 41. Direct-incidence damping block; 42. Oblique-incidence damping block; 5. Shell; 6. Sound insulation layer; 71. Direct-incidence interface; 72. Oblique-incidence interface; 8. Sound-absorbing material; 100. Combined ultrasonic transducer; 101. Direct-incidence channel; 102. Oblique-incidence channel. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0036] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0037] Example 1

[0038] At present, with the increase of thickness, there is a lot of noise interference in the ultrasonic detection of titanium alloy welds. In addition, due to the uneven structure of the plate, the acoustic performance varies greatly, resulting in the detection sensitivity being too high or too low during the ultrasonic detection process, resulting in inaccurate defect quantification and inability to effectively assess the quality of the welded joint.

[0039] The adaptive sensitivity ultrasonic detection method uses a combined ultrasonic transducer 100 to achieve real-time dynamic tracking of the acoustic performance of thick titanium alloy plates, and compensates the tracking data to the scanning detection signal in real time, achieving the purpose of adaptive adjustment of the detection sensitivity, and effectively solving the problem of inaccurate defect quantification caused by uneven materials. At present, there are few studies on the dynamic compensation method of ultrasonic detection sensitivity of titanium alloy welds, and in the literature and patent technology search, there are no related reports and research on this technology in the detection of thick titanium alloy welds.

[0040] To this end, the present invention proposes an adaptive sensitivity ultrasonic detection method, such as Figures 1 to 3 As shown, a combined ultrasonic transducer 100 is designed, and a dual-channel device with a direct-incident channel 101 and an oblique-incident channel 102 is used to realize the synchronization of material acoustic performance evaluation and weld detection, a compensation feedback algorithm is developed, and key process parameters such as the characteristics and excitation principle of the combined ultrasonic transducer 100 are clarified, thereby realizing accurate quantitative evaluation of thick plate titanium alloy weld defects.

[0041] The present invention proposes an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds, which selects a combined ultrasonic transducer 100 with oblique incidence of single crystal longitudinal waves and direct incidence of single crystal longitudinal waves, sets excitation parameters, performs testing and calibration, sets adaptive compensation, tests the signal-to-noise ratio, and finally performs scanning detection.

[0042] The thick plate titanium alloy weld adaptive sensitivity ultrasonic detection method comprises the following steps:

[0043] Step 1: Design of combined ultrasonic transducer 100: Figure 1As shown, the combined ultrasonic transducer 100 includes a straight-incidence channel 101 and an oblique-incidence channel 102, wherein the straight-incidence channel 101 is used to evaluate the acoustic properties of the material, and the oblique-incidence channel 102 is used to detect the titanium alloy weld. A sound insulation layer 6 is arranged between the straight-incidence channel 101 and the oblique-incidence channel 102, a straight-incidence wafer 31 is arranged in the straight-incidence channel 101, and an oblique-incidence wafer 32 is arranged in the oblique-incidence channel 102. Both the straight-incidence wafer 31 and the oblique-incidence wafer 32 are made of piezoelectric composite materials. The shape, size, and angle of the straight-incidence chip 31 with the horizontal direction match the shape, size, and angle of the oblique-incidence chip 32 with the horizontal direction; the manufacture of the combined ultrasonic transducer 100 requires spectrum testing, and the center frequency of the combined ultrasonic transducer 100 should be within the specified range. The straight-incidence channel 101 and the oblique-incidence channel 102 are tested separately. The center frequency of the oblique-incidence channel 102 is f1, and the center frequency of the straight-incidence channel 101 is f2. f1 and f2 should meet the following requirements:

[0044]

[0045] Specifically, in this embodiment, the center frequency of the oblique incident channel 102 is f1=4.97 MHz, and the center frequency of the straight incident channel 101 is f2=4.91 MHz, then,

[0046]

[0047] Therefore, f1 and f2 meet the requirements.

[0048] Specifically, the shape, size, and angle with the horizontal direction of the direct-incidence chip 31 match the shape, size, and angle with the horizontal direction of the oblique-incidence chip 32, which means that: the shapes of the direct-incidence chip 31 and the oblique-incidence chip 32 are both circular, the diameter of the oblique-incidence chip 32 ranges from 10 to 20 mm, and the diameter of the direct-incidence chip 31 is 10 mm; the angle between the oblique-incidence chip 32 and the horizontal direction is 15.7° or 19.4°, and the angle between the direct-incidence chip 31 and the horizontal direction is 0°.

[0049] In this embodiment, the diameter of the oblique-incident wafer 32 is 14 mm, and the angle between the oblique-incident wafer 32 and the horizontal direction is 15.7°.

[0050] Specifically, the center frequency of the combined ultrasonic transducer 100 in step 1 should be within a prescribed range, which means that the center frequency is 2 to 5 MHz.

[0051] In this embodiment, the center frequency of step 1 is 4.91-4.97 MHz.

[0052] More specifically, Figure 1 As shown, the combined ultrasonic transducer 100 also includes a shell 5, a protective film 1 is arranged at the bottom of the combined ultrasonic transducer 100, the shell 5 and the protective film 1 form a straight-incidence channel 101 and an oblique-incidence channel 102, a wedge block 2 is arranged below the oblique-incidence chip 32, an oblique-incidence damping block 42 is arranged above the oblique-incidence chip 32, and a straight-incidence damping block 41 is arranged below the straight-incidence chip 31; a straight-incidence interface 71 is arranged above the straight-incidence channel 101, and an oblique-incidence interface 72 is arranged above the oblique-incidence channel 102; and sound-absorbing materials 8 are arranged inside the straight-incidence channel 101 and the oblique-incidence channel 102.

[0053] Step 2, detection system design: The detection system includes a multi-channel ultrasonic detection collector, a host computer software and a combined ultrasonic transducer 100, the combined ultrasonic transducer 100 is connected to the multi-channel ultrasonic detection collector, and the multi-channel ultrasonic detection collector is connected to the host computer software; the host computer software can adjust the excitation parameters and receiving parameters of the multi-channel ultrasonic detection collector, and the multi-channel ultrasonic detection collector can adjust the excitation parameters and receiving parameters of the combined ultrasonic transducer 100; the direct incidence channel 101 and the oblique incidence channel 102 are synchronously performed, and the excitation parameters and receiving parameters of the combined ultrasonic transducer 100 of the direct incidence channel 101 and the oblique incidence channel 102 should be consistent; and the detection sensitivity can be adaptively adjusted and set in the host computer software, and the adaptive adjustment setting program includes the following steps:

[0054] (1) Test the initial acoustic attenuation coefficient α0 on the thick plate titanium alloy weld ultrasonic testing comparison test block;

[0055] (2) During the workpiece detection process, the acoustic attenuation coefficient α(t) of the detection area is tested in real time using the direct incidence channel 101;

[0056] (3) The ultrasonic signal acquired by the oblique incident channel 102 is defined as S(t), and the compensated ultrasonic signal is S(t)+2L(t')×(α(t)-α0), where L(t') is the sound path corresponding to each signal point in a single sampling period;

[0057] In this embodiment, the multi-channel ultrasonic detection collector is a four-channel ultrasonic detection collector.

[0058] Step 3, testing and calibration: connecting the combined ultrasonic transducer 100 to the multi-channel ultrasonic detection collector, and the multi-channel ultrasonic detection collector adjusts the excitation parameters of the direct-incident channel 101 and the oblique-incident channel 102, so that the excitation parameters of the direct-incident channel 101 are consistent with the excitation parameters of the oblique-incident channel 102; first, calculating the acoustic attenuation coefficient according to the two bottom surface reflection waves of the direct-incident channel 101, and secondly, testing the front length and refraction angle of the oblique-incident channel 102, and making a distance-amplitude curve, and setting the scanning sensitivity;

[0059] In this embodiment, first, the combined ultrasonic transducer 100 is stably coupled to a 180 mm thick titanium alloy weld comparison test block, the temperature of the comparison test block is 29.5°C, and a CG-08 coupling agent is used. The sound attenuation coefficient is calculated based on the two bottom surface reflection waves of the direct incident channel 101, and the calculated value is 0.092 dB / mm; secondly, the front length of the oblique incident channel 102 is tested to be 13 mm, the refraction angle is 45.6°, and a distance-amplitude curve is produced, and the scanning sensitivity is set to φ3×40mm-16dB.

[0060] Step 4: Signal-to-noise ratio test: Use a tested and calibrated detection system to perform a signal-to-noise ratio test on the workpiece to be tested. To keep the test conditions consistent, randomly select at least 3 positions within the full length of the weld to be tested for testing. The signal-to-noise ratio test requirement is met when the scattered wave signal at the maximum detection sound path of the oblique incidence channel 102 is not higher than the scanning sensitivity curve.

[0061] In this embodiment, the thickness of a titanium alloy weld to be detected is 135 mm, the temperature is 35.6 ° C, and the CG-08 coupling agent is also applied. The parameter settings of the detection system are not changed. The noise signal at the maximum detection sound path (191.7 mm) is checked at the beginning, middle and end of the weld length. It is lower than the scanning sensitivity curve, as shown in Figure 3 As shown, the signal-to-noise ratio test requirements are met.

[0062] Step 5: Scanning and evaluation: Keep the combined ultrasonic transducer 100 well coupled with the workpiece, scan the weld and evaluate the abnormal reflected waves according to the procedures specified in the standard, and evaluate the level.

[0063] In this embodiment, the combined ultrasonic transducer 100 is kept well coupled with the workpiece, and a zigzag scan is performed along the weld according to the procedure specified in GB / T35361-2017. When defects occur, the defects are characterized by front-to-back, left-to-right, corner and surround methods, and the -6dB method is used to measure the defect indication length, and the level is assessed according to the acceptance requirements.

[0064] Specifically, the multi-channel ultrasonic detection collector has at least two independent channels, the channels of the multi-channel ultrasonic detection collector can excite and receive signals in parallel, and the host computer software can adjust the excitation parameters and receiving parameters of the channels of the multi-channel ultrasonic detection collector.

[0065] In this embodiment, the multi-channel ultrasonic detection collector has four independent channels.

[0066] Specifically, the excitation parameters and receiving parameters of the combined ultrasonic transducer 100 of the direct-incident channel 101 and the oblique-incident channel 102 in step 2 should be consistent, which means that the excitation pulse type, excitation pulse voltage, excitation pulse width, pulse repetition frequency and receiving filter of the direct-incident channel 101 are exactly the same as the excitation pulse type, excitation pulse voltage, excitation pulse width, pulse repetition frequency and receiving filter of the oblique-incident channel 102.

[0067] In this embodiment, the excitation pulse types of the direct-incident channel 101 and the oblique-incident channel 102 are both set to negative square waves, the excitation pulse voltage is both set to 150V, the excitation pulse width is both set to 100nS, the pulse repetition frequency is both set to 1500, and the receiving filter is both bandpass (3.5-6.5MHz).

[0068] Specifically, in step 4, a signal-to-noise ratio test is performed on the workpiece to be tested using a tested and calibrated detection system. To maintain consistency in the test conditions means that the temperature difference between the comparison test block and the workpiece to be tested is ≤19°C, and the coupling agent used should be consistent.

[0069] In this embodiment, during the test and calibration in step three, the temperature of the comparison test block is 29.5°C, and CG-08 coupling agent is used; during the signal-to-noise ratio test in step four, the temperature of the workpiece to be tested is 35.6°C, and CG-08 coupling agent is also applied; the temperature difference between the comparison test block and the workpiece to be tested is 6.1°C, which meets the requirement that the temperature difference between the comparison test block and the workpiece to be tested is ≤19°C.

[0070] Specifically, the maximum detection sound path of the oblique incident channel 102 at the test position in step 4 means that when the oblique incident chip 32 is at an angle of 15.7° with the horizontal direction, the sound path is 1.42 times the thickness of the base material; when the oblique incident chip 32 is at an angle of 19.4° with the horizontal direction, the sound path is 2 times the thickness of the base material.

[0071] In this embodiment, the angle between the oblique incident chip 32 and the horizontal direction is 15.7°, the thickness of the base material (titanium alloy weld to be detected) is 135 mm, the sound path is 1.42 times the base material thickness, and the sound path is 1.42*135 mm=191.7 mm.

[0072] The invention provides a method for ultrasonic detection of thick plate titanium alloy welds with adaptive sensitivity, the maximum detection weld thickness is ≥160mm, the detection sensitivity can reach φ2×40mm-18dB, and the sensitivity error is ≤3dB.

[0073] The present invention provides an adaptive sensitivity ultrasonic detection method for thick plate titanium alloy welds, which utilizes a combined ultrasonic transducer 100 to achieve synchronization of acoustic performance testing of the scanning area and weld detection, and combines a dual-channel system of a direct-incident channel 101 and an oblique-incident channel 102 and a compensation algorithm to achieve the purpose of real-time dynamic adjustment of detection sensitivity, thereby meeting the needs of high-precision quantitative evaluation of thick plate weld defects.

[0074] Example 2

[0075] In this embodiment, different from the embodiment 1, the diameter of the oblique incident wafer 32 is 10 mm, the angle between the oblique incident wafer 32 and the horizontal direction is 19.4°, the sound path is twice the thickness of the base material, and the sound path is 270 mm.

[0076] In step 4, the thickness of a titanium alloy weld to be tested is 135mm and the temperature is 35.6℃. The CG-08 coupling agent is also applied without changing the parameter settings of the detection system. The noise signal at the maximum detection sound range (270mm) is checked at the starting, middle and end parts of the weld length. It is lower than the scanning sensitivity curve and meets the signal-to-noise ratio test requirements.

[0077] Example 3

[0078] In this embodiment, different from the embodiment 1, the diameter of the oblique-incidence wafer 32 is 20 mm.

[0079] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for ultrasonic testing of thick plate titanium alloy welds with adaptive sensitivity, characterized in that: The method for ultrasonic testing of thick plate titanium alloy welds with adaptive sensitivity comprises the following steps: Step 1: Design of a combined ultrasonic transducer (100): The combined ultrasonic transducer (100) comprises a straight-incidence channel (101) and an oblique-incidence channel (102), wherein the straight-incidence channel (101) is used for evaluating the acoustic properties of a material, and the oblique-incidence channel (102) is used for detecting a titanium alloy weld. A sound insulation layer (6) is arranged between the straight-incidence channel (101) and the oblique-incidence channel (102), a straight-incidence wafer (31) is arranged in the straight-incidence channel (101), and an oblique-incidence wafer (32) is arranged in the oblique-incidence channel (102), wherein the straight-incidence wafer (31) and the oblique-incidence wafer (32) are arranged in the oblique-incidence channel (102). The chips (32) are all piezoelectric composite materials. The shape, size, and angle between the direct-incidence chip (31) and the horizontal direction match the shape, size, and angle between the direct-incidence chip (32) and the horizontal direction. The combined ultrasonic transducer (100) is manufactured to undergo spectrum testing. The center frequency of the combined ultrasonic transducer (100) should be within a specified range. The direct-incidence channel (101) and the oblique-incidence channel (102) are tested separately. The center frequency of the oblique-incidence channel (102) is f1, and the center frequency of the direct-incidence channel (101) is f2. f1 and f2 should meet the following requirements: Step 2, design of the detection system: the detection system comprises a multi-channel ultrasonic detection collector, a host computer software and a combined ultrasonic transducer (100), wherein the combined ultrasonic transducer (100) is connected to the multi-channel ultrasonic detection collector, and the multi-channel ultrasonic detection collector is connected to the host computer software; the direct incidence channel (101) and the oblique incidence channel (102) are synchronously performed, and the excitation parameters and receiving parameters of the combined ultrasonic transducer (100) of the direct incidence channel (101) and the oblique incidence channel (102) should be consistent; and the detection sensitivity can be adaptively adjusted and set in the host computer software, and the adaptive adjustment setting program comprises the following steps: (1) Test the initial acoustic attenuation coefficient α0 on the thick plate titanium alloy weld ultrasonic testing comparison test block; (2) During the workpiece detection process, the acoustic attenuation coefficient α(t) of the detection area is tested in real time using the direct incidence channel (101); (3) The ultrasonic signal acquired by the oblique incident channel (102) is defined as S(t), and the compensated ultrasonic signal is S(t)+2L(t')×(α(t)-α0), where L(t') is the sound path corresponding to each signal point in a single sampling period; Step 3, testing and calibration: respectively adjusting the excitation parameters of the direct-incidence channel (101) and the oblique-incidence channel (102) so that the excitation parameters of the direct-incidence channel (101) are consistent with the excitation parameters of the oblique-incidence channel (102); first, calculating the acoustic attenuation coefficient according to the two bottom surface reflection waves of the direct-incidence channel (101); secondly, testing the front length and refraction angle of the oblique-incidence channel (102), making a distance-amplitude curve, and setting the scanning sensitivity; Step 4, signal-to-noise ratio test: Use a tested and calibrated detection system to perform a signal-to-noise ratio test on the workpiece to be tested. The test conditions must be kept consistent. At least three positions are randomly selected within the entire length of the weld to be tested for testing. The signal-to-noise ratio test requirement is met when the scattered wave signal at the maximum detection sound path of the oblique incidence channel (102) is not higher than the scanning sensitivity curve. Step 5: Scanning and evaluation: Keep the combined ultrasonic transducer (100) well coupled with the workpiece, scan the weld and evaluate the abnormal reflected waves according to the procedures specified in the standard, and evaluate the level.

2. The method for adaptive sensitivity ultrasonic detection of thick plate titanium alloy welds according to claim 1 is characterized in that: The shape, size, and angle between the directly incident wafer (31) and the horizontal direction match the shape, size, and angle between the directly incident wafer (31) and the oblique incident wafer (32), which means that: the shapes of the directly incident wafer (31) and the oblique incident wafer (32) are both circular, the diameter of the oblique incident wafer (32) is in the range of 10 to 20 mm, and the diameter of the directly incident wafer (31) is 10 mm; the angle between the oblique incident wafer (32) and the horizontal direction is 15.7° or 19.4°, and the angle between the directly incident wafer (31) and the horizontal direction is 0°.

3. The method for adaptive sensitivity ultrasonic detection of thick plate titanium alloy welds according to claim 2 is characterized in that: The center frequency of the combined ultrasonic transducer (100) in step 1 should be within a specified range, which means that the center frequency is 2 to 5 MHz.

4. The method for adaptive sensitivity ultrasonic detection of thick plate titanium alloy welds according to claim 3 is characterized in that: The multi-channel ultrasonic detection collector has at least two independent channels, and the channels of the multi-channel ultrasonic detection collector can excite and receive signals in parallel.

5. The method for adaptive sensitivity ultrasonic detection of thick plate titanium alloy welds according to claim 4 is characterized in that: The excitation parameters and receiving parameters of the combined ultrasonic transducer (100) of the direct-incident channel (101) and the oblique-incident channel (102) in step 2 should be consistent, which means that the excitation pulse type, excitation pulse voltage, excitation pulse width, pulse repetition frequency and receiving filter of the direct-incident channel (101) are exactly the same as the excitation pulse type, excitation pulse voltage, excitation pulse width, pulse repetition frequency and receiving filter of the oblique-incident channel (102).

6. The method for adaptive sensitivity ultrasonic testing of thick plate titanium alloy welds according to claim 5 is characterized in that: In step 4, the signal-to-noise ratio test is performed on the workpiece to be tested using the tested and calibrated detection system. To maintain the consistency of the test conditions means that the temperature difference between the comparison test block and the workpiece to be tested is ≤19°C, and the coupling agent used should be consistent.

7. The method for adaptive sensitivity ultrasonic testing of thick plate titanium alloy welds according to claim 6, characterized in that: In step 4, the maximum detection sound path of the oblique incident channel (102) at the test position is: when the angle between the oblique incident chip (32) and the horizontal direction is 15.7°, the sound path is 1.42 times the thickness of the base material; when the angle between the oblique incident chip (32) and the horizontal direction is 19.4°, the sound path is 2 times the thickness of the base material.

8. The method for adaptive sensitivity ultrasonic testing of thick plate titanium alloy welds according to claim 1, characterized in that: The maximum detectable weld thickness is ≥160mm, the detection sensitivity can reach φ2×40mm-18dB, and the sensitivity error is ≤3dB.

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