An ultrasonic phased array inspection method for weld seams

Abstract

The present invention relates to the technical field of weld inspection, and particularly to a method for ultrasonic phased array inspection of welds. First, the weld is divided into a surface weld, a middle-layer weld, and an inner-layer weld arranged in sequence from outside to inside along the thickness direction of the weld; then, a single-sided double-sided detection method is adopted, and a phased array detector is used to excite creeping waves to scan the surface weld, excite transverse waves to scan the middle-layer weld, and excite longitudinal waves to scan the inner-layer weld; after that, one side of the scan data map of the surface weld is horizontally flipped and then superimposed on the other side of the scan data map of the surface weld; one side of the scan data map of the middle-layer weld is horizontally flipped and then superimposed on the other side of the scan data map of the middle-layer weld; one side of the scan data map of the inner-layer weld is horizontally flipped and then superimposed on the other side of the scan data map of the inner-layer weld; interference signals are shielded and defect signals are enhanced to achieve precise detection of internal defects of the entire weld.

Description

Technical Field

[0001] The present invention relates to the technical field of weld detection, and particularly to an ultrasonic phased array inspection method for welds. Background Art

[0002] In recent years, a large number of supercritical thermal power generating units have been put into production. Due to their high parameters and large capacity, supercritical units have adopted a large number of high-grade new materials, such as P92 / F92, Super304, GH783, HR3C, etc. To ensure the performance requirements, the high-temperature superheater outlet header pipe joint is a key component used in supercritical thermal power generating units. To meet the usage requirements, the high-temperature superheater outlet header pipe joint needs to be processed by dissimilar steel welding. The high-temperature superheater outlet header pipe joint is welded by a martensitic steel pipe and an austenitic steel pipe, and the welding consumables used are ERNiCr-3 nickel-based welding consumables. Since austenitic steel belongs to coarse-grained steel and martensitic steel belongs to fine-grained steel, there are significant differences in the chemical composition and microstructure properties between austenitic steel and martensitic steel. During the welding process, open defects such as lack of penetration and hot cracks are likely to occur inside the weld, and the open defects may appear at various positions of the weld.

[0003] Currently, for the detection of weld defects in the high-temperature superheater outlet header pipe joint, penetrant testing is generally used. Since the internal cracks in the weld have not extended to the outer surface, penetrant testing cannot detect them. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that currently, penetrant testing cannot detect internal defects in dissimilar steel welds.

[0005] To solve the above technical problem, the object of the present invention is to provide an ultrasonic phased array inspection method for welds, which is used to detect open defects in a to-be-tested weld between an austenitic steel pipe and a martensitic steel pipe, and includes the following steps:

[0006] Step S1: Divide the to-be-tested weld into a surface weld, a middle weld, and an inner weld arranged in sequence from outside to inside along the thickness direction of the to-be-tested weld;

[0007] Step S2: Adopt a single-sided double-sided detection method, and use a phased array tester to scan the surface weld, the middle weld, and the inner weld respectively to obtain a surface weld scan pattern, a middle weld scan pattern, and an inner weld scan pattern; creeping wave is used when scanning the surface weld, transverse wave is used when scanning the middle weld, and longitudinal wave is used when scanning the inner weld;

[0008] Step S3: Horizontally flip one side of the surface weld inspection data atlas and overlay it with the other side of the surface weld inspection data atlas; horizontally flip one side of the middle weld inspection data atlas and overlay it with the other side of the middle weld inspection data atlas; horizontally flip one side of the inner weld inspection data atlas and overlay it with the other side of the inner weld inspection data atlas.

[0009] As a preferred solution, in step S2, the surface weld, the middle weld, and the inner weld are detected by means of full direct wave fan-shaped scanning.

[0010] As a preferred solution, in step S2, the surface weld is detected on both sides of the weld to be tested by using a first wedge block, and the angle of the first wedge block is greater than or equal to 27° and less than or equal to 37°.

[0011] As a preferred solution, in step S2, when scanning the middle weld, the fan-shaped scanning angle is greater than or equal to 40° and less than or equal to 72°.

[0012] As a preferred solution, in step S2, the inner weld is detected on both sides of the weld to be tested by using a third wedge block, and the angle of the third wedge block is greater than or equal to 22.3° and less than or equal to 27.1°.

[0013] As a preferred solution, in step S2, the bottom opening defect of the inner weld is scanned by using phased array to excite transverse waves.

[0014] As a preferred solution, before step S1, it further includes:

[0015] Step S0: Calibrate the sensitivity of the ultrasonic phased array inspection system by using a reference block. The reference block includes an austenitic steel block and a martensitic steel block horizontally welded to the end of the austenitic steel block. The weld between the austenitic steel block and the martensitic steel block forms a calibration weld, and the structure of the calibration weld is the same as that of the weld to be detected;

[0016] The welding end of the austenitic steel block is provided with a first welding groove, and a first notch, a second notch, and a third notch are provided at the end face of the first welding groove. The first notch is located in the surface weld; the second notch is located in the middle weld; the third notch is located in the inner weld;

[0017] The welding end of the martensitic steel block is provided with a second welding groove, and a fourth notch, a fifth notch, and a sixth notch are provided at the end face of the second welding groove. The fourth notch is located in the surface weld, the fifth notch is located in the middle weld, and the sixth notch is located in the inner weld.

[0018] As a preferred solution, the first notch, the second notch and the third notch are arranged at intervals in sequence from the rear to the front; the fourth notch, the fifth notch and the sixth notch are arranged at intervals in sequence from the rear to the front.

[0019] As a preferred solution, the middle part of the calibration weld seam is provided with a first simulation hole, a second simulation hole and a third simulation hole which are arranged at intervals from top to bottom in sequence; the first simulation hole, the second simulation hole and the third simulation hole all extend in the front-rear direction; the first simulation hole is located in the surface weld seam; the second simulation hole is located in the middle weld seam, and the third simulation hole is located in the inner weld seam.

[0020] As a preferred solution, the upper end of the calibration weld seam is provided with a first groove with an upward opening, and the lower end of the calibration weld seam is provided with a second groove with a downward opening.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] In the weld ultrasonic phased array inspection method of the present invention, first, the weld to be measured is divided into a surface weld seam, a middle weld seam and an inner weld seam which are arranged in sequence from the outside to the inside along the thickness direction of the weld to be measured; then, a single-sided double-sided detection method is adopted, and a phased array detector is used to excite creeping waves to scan the surface weld seam to obtain a scanning data map of the surface weld seam, use the phased array to excite transverse waves to scan the middle weld seam to obtain a scanning data map of the middle weld seam, and use the phased array to excite longitudinal waves to scan the inner weld seam to obtain a scanning data map of the inner weld seam; then, one side map of the scanning data map of the surface weld seam is horizontally flipped and then superimposed with the other side map of the scanning data map of the surface weld seam; one side map of the scanning data map of the middle weld seam is horizontally flipped and then superimposed with the other side map of the scanning data map of the middle weld seam; one side map of the scanning data map of the inner weld seam is horizontally flipped and then superimposed with the other side map of the scanning data map of the inner weld seam; so that the maps of each layer are synthesized and enhanced, thereby shielding the interference signals and enhancing the defect signals, so as to realize the accurate detection of the internal open defects of the entire weld seam. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram for ultrasonic phased array detection of the weld to be measured;

[0024] Figure 2 It is the front view of the contrast test block;

[0025] Figure 3 It is the top view of the contrast test block;

[0026] Figure 4 It is the side view of the contrast test block;

[0027] In the figure, 1 is an austenitic steel pipe, 2 is a martensitic steel pipe, 3 is the weld to be tested, 4 is a reference block, 41 is an austenitic steel block, 411 is the first notch, 412 is the second notch, 413 is the third notch, 42 is a martensitic steel block, 421 is the fourth notch, 422 is the fifth notch, 423 is the sixth notch, 43 is a calibration weld, 431 is the first simulated hole, 432 is the second simulated hole, 433 is the third simulated hole, 434 is the first groove, 435 is the second groove, and 5 is an ultrasonic phased array detector. Specific implementation mode

[0028] The following combines the drawings and embodiments to further describe in detail the specific implementation mode of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. It should be understood that the present invention uses the terms "first", "second", etc. to describe various information, but these information should not be limited to these terms, and these terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0030] The weld ultrasonic phased array inspection method of the present invention is used to detect the open defect 3 of the weld to be tested between the austenitic steel pipe 1 and the martensitic steel pipe 2. A preferred embodiment of the weld ultrasonic phased array inspection method includes the following steps:

[0031] Step S1: Divide the weld to be tested 3 into a surface weld, a middle weld, and an inner weld arranged in sequence from outside to inside along the thickness direction of the weld to be tested 3;

[0032] Step S2: Adopt a single-sided double-sided detection method, and use the phased array detector 5 to scan the surface weld, the middle weld, and the inner weld respectively to obtain a surface weld scan pattern, a middle weld scan pattern, and an inner weld scan pattern; creeping waves are used when scanning the surface weld, transverse waves are used when scanning the middle weld, and longitudinal waves are used when scanning the inner weld;

[0033] Specifically, the single-sided double-sided detection method is adopted. The phased array detector 5 is used to excite creeping waves to scan the surface weld, and the scanning data atlas of the surface weld is obtained; the single-sided double-sided detection method is adopted, and the phased array detector 5 is used to excite shear waves to scan the middle-layer weld, and the scanning data atlas of the middle-layer weld is obtained; the single-sided double-sided detection method is adopted, and the phased array detector 5 is used to excite longitudinal waves to scan the inner-layer weld, and the scanning data atlas of the inner-layer weld is obtained.

[0034] Step S3: Horizontally flip one side of the scanning data atlas of the surface weld and then superimpose it on the other side of the scanning data atlas of the surface weld; horizontally flip one side of the scanning data atlas of the middle-layer weld and then superimpose it on the other side of the scanning data atlas of the middle-layer weld; horizontally flip one side of the scanning data atlas of the inner-layer weld and then superimpose it on the other side of the scanning data atlas of the inner-layer weld. This enhances the synthesis of the defect atlas, shields the interference signals, and enhances the defect signals, thereby realizing the detection of the open defects inside the entire weld to be measured.

[0035] Among them, the specific method of single-sided double-sided scanning is carried out according to the regulations in JB / T4730.3-2005. Using single-sided double-sided full direct wave scanning of the weld to be measured 3 can reduce the scattered echoes. The scanning directions of the surface weld, the middle-layer weld, and the inner-layer weld are all along the circumference of the fusion line of the weld to be measured 3. The ultrasonic creeping wave is a compressional longitudinal wave with a refraction angle of 90°. At this time, the longitudinal wave incident angle is called the first critical angle α. For the organic glass / steel interface, α = 27.6°, and for the organic glass / austenitic steel interface, α = 30.4°. Compared with ultrasonic surface waves, creeping waves are not sensitive to surface roughness and are suitable for the detection of surface and near-surface defects in austenitic steel coarse-grained welds. Most of the beams of the creeping wave return along the original path after being reflected by the open defect. Therefore, the surface and near-surface crack echoes of the weld to be measured 3 can be obtained.

[0036] In step S2, when detecting the surface weld seam, the first wedge block is sequentially placed on both sides of the weld seam 3 to be detected to detect the surface weld seam. Specifically, the first wedge block is a plexiglass inclined wedge block. In conventional ultrasonic creeping wave detection, a 27.6° plexiglass inclined wedge block needs to be selected on the side of the weld seam 3 to be detected close to the martensitic steel pipe 2, and a 30.4° plexiglass inclined wedge block needs to be selected on the side of the weld seam 3 to be detected close to the austenitic steel pipe 1. However, the differences in the processing parameters of different inclined wedge blocks are not conducive to the superposition processing of the detection spectrograms in the subsequent step S3, resulting in poor processing effects of the detection spectrograms. When using the phased array sector scanning technology, the effective fan scanning angle after the combination of phased array ultrasound and the wedge block is generally the refraction angle ±20°. By using the phased array multi-angle sector scanning technology, the creeping wave detection angle can be optimized, and it is not necessary to only enter at a fixed angle. The same angle plexiglass wedge block can be selected to achieve ultrasonic creeping wave detection on both the martensitic steel side and the austenitic steel side. Therefore, using the ultrasonic phased array technology to excite the creeping wave changes the problem that two plexiglass wedge blocks are required when detecting the traditional creeping wave detection beam. Preferably, in this embodiment, the angle of the first wedge block is greater than or equal to 27° and less than or equal to 37°. In this embodiment, the welding material between the austenitic steel pipe 1 and the martensitic steel pipe 2 is ERNiCr-3 nickel-based welding material. The ERNiCr-3 nickel-based welding material belongs to coarse-grained steel. To reduce grain scattering and take into account the detection sensitivity, when detecting the surface weld seam, the detection frequency of the ultrasonic probe is selected from 2Mhz to 3Mhz. To reduce the interface interference signal of the contact surface between the first wedge block and the austenitic steel pipe 1 or the martensitic steel pipe 2 and the influence of coarse-grained material scattering, when detecting the surface weld seam, the ultrasonic probe uses a dual-crystal linear array or a planar array phased array probe. The main defects targeted by detecting the surface weld seam are specifically cracks, lack of fusion, pores, and slag inclusions located in the surface weld seam.

[0037] In step S2, when detecting the middle layer weld seam, the second wedge is used to detect the inner layer weld seam on both sides of the weld seam to be detected. The angle of the second wedge is greater than or equal to 42° to 52°, and preferably the angle of the second wedge is 47°. An organic glass inclined wedge with an angle of 47° is selected, the longitudinal wave sound velocity is 2730 mm / s, the refraction angle of the corresponding shear wave in steel is 60°, and the corresponding fan-shaped scanning angle range is 40° to 80°. Preferably, in this embodiment, when detecting the middle layer weld seam, the fan-shaped scanning angle range is 40° to 72°, thus avoiding the decrease in detection sensitivity caused by excessive deflection angle, excessive beam deformation, excessive sound path, and reduction of main beam energy. In this embodiment, a good detection effect can be achieved for the open defect at the bottom of the inner layer weld seam by using the end corner reflection echo. When the longitudinal wave is incident, the longitudinal wave will separate a certain amount of shear wave during the two reflections at the bottom end corner, resulting in the dispersion of the longitudinal wave energy, and further resulting in the reduction of the reflectivity of the longitudinal wave at the bottom surface of the inner layer weld seam within the full angle range; while the reflection of the shear wave at the bottom end corner of the inner layer weld seam can be 100% total reflection within a certain angle range; therefore, in this embodiment, the shear wave fan-shaped scan is used to detect the open defect at the bottom surface of the inner layer weld seam. The angle range of 100% reflectivity of the shear wave at the bottom end corner is 35 to 55°, which is within the fan-shaped scanning angle range of 40 to 72°. Therefore, setting the fan-shaped scanning angle to 40 to 72° can meet the detection requirements for the open defect at the bottom surface of the inner layer weld seam. When detecting the middle layer weld seam defect, single-sided double-sided scanning is adopted. The ultrasonic shear wave can detect defects such as incomplete fusion of the groove and bottom surface open crack in the middle area of this side without passing through the weld seam to be detected, reducing the influence of the columnar coarse grain structure in the middle of the weld seam to be detected and improving the defect detection rate of the middle layer weld seam. Among them, the middle area of this side refers to the side of the weld seam where the ultrasonic probe is located. The shear wave fan-shaped scan is excited by using a one-dimensional linear array self-focusing phased array probe. The curvature radius of the phased array ultrasonic probe wafer is selected according to the curvature of the metal tube to be inspected. The detection frequency of the ultrasonic probe is preferably 2 MHz. The curvature radius of the second wedge is greater than or equal to the curvature radius of the metal tube to be inspected, and the maximum value of the gap between the inner side surface of the second wedge and the outer side surface of the metal tube to be inspected is less than 0.5 mm to reduce the quantitative error caused by the fluctuation of the coupling gap and the inclination of the second wedge during the detection process.

[0038] In step S2, when detecting the inner layer weld seam, a phased array detector 5 is used to excite longitudinal wave sector scanning to detect the lack of fusion, incomplete penetration, porosity and slag inclusion defects in the inner layer weld seam; preferably, when using the phased array detector 5 to excite longitudinal wave sector scanning to detect the inner layer weld seam, the opening defects of the middle layer weld seam are also detected. Using longitudinal wave detection can effectively improve the detection signal-to-noise ratio and detect the internal defects of the inner layer weld seam; however, the longitudinal wave will be affected by the deformed wave, resulting in difficulties in positioning and qualitative analysis, so direct wave detection is used. There are two disadvantages in using longitudinal wave to detect the weld seam 3 to be measured: First, due to the limited angle offset of the longitudinal wave and the use of direct wave, there are blind areas in the surface weld seam and the middle layer weld seam during longitudinal wave detection; Second, a strong transverse wave is separated during the two reflections of the longitudinal wave at the bottom end angle, and the reflectivity of the bottom end angle is very low during longitudinal wave detection, and the sensitivity angle to the bottom opening defect is low. And the above two disadvantages can be compensated by the above-mentioned creeping wave sector scanning and transverse wave sector scanning. That is, the blind area of the surface weld seam is supplemented by phased array ultrasonic creeping wave scanning detection; the opening defects such as incomplete penetration and cracks at the bottom of the inner layer weld seam are supplemented by transverse wave sector scanning detection. When detecting the inner layer weld seam, a dual-crystal line or planar array phased array probe is used, and the detection frequency of the probe is selected as 2 MHz. In this embodiment, in step S2, a third wedge block is used to detect the inner layer weld seam on both sides of the weld seam, and the angle of the second wedge block is greater than or equal to 22.3° and less than or equal to 27.1°, corresponding to the refracted longitudinal wave angle range in steel of 55° to 80°, preferably the refraction angle is 60°, corresponding to the fan scan angle range of 40° to 80°. Because the longitudinal wave has strong penetration ability and relatively small attenuation, it is beneficial to reduce the detection blind area of the inner layer weld seam.

[0039] In this embodiment, a full direct wave sector scanning method is used to detect the surface weld seam, the middle layer weld seam and the inner layer weld seam. Before step S1, it also includes:

[0040] Step S0: Use the reference block 4 to calibrate the sensitivity of the ultrasonic phased array detection system. The reference block 4 includes an austenitic steel block 41 and a martensitic steel block 42 horizontally welded to the end of the austenitic steel block 41. The weld seam between the austenitic steel block 41 and the martensitic steel block 42 forms a calibration weld seam 43, and the structure of the calibration weld seam 43 is the same as the structure of the weld seam 3 to be detected;

[0041] The welding end of the austenitic steel block 41 is provided with a first welding groove, and a first notch 411, a second notch 412 and a third notch 413 are provided at the end face of the first welding groove. The first notch 411 is located in the surface weld seam; the second notch 412 is located in the middle layer weld seam; the third notch 413 is located in the inner layer weld seam;

[0042] The welding end of the martensitic steel block 42 is provided with a second welding groove, and a fourth notch 421, a fifth notch 422 and a sixth notch 423 are provided at the end face of the second welding groove. The fourth notch 421 is located in the surface weld seam, the fifth notch 422 is located in the middle layer weld seam, and the sixth notch 423 is located in the inner layer weld seam.

[0043] Among them, the first notch 411, the second notch 412, and the third notch 412 are arranged at intervals from back to front in sequence; the fourth notch 421, the fifth notch 422, and the sixth notch 423 are arranged at intervals from back to front in sequence; the middle part of the calibration weld 43 is provided with a first simulation hole 431, a second simulation hole 432, and a third simulation hole 433 which are arranged at intervals from top to bottom in sequence; the first simulation hole 431, the second simulation hole 432, and the third simulation hole 433 all extend in the front-back direction; the first simulation hole 431 is located in the surface layer weld; the second simulation hole 432 is located in the middle layer weld, and the third simulation hole 433 is located in the inner layer weld; the upper end of the calibration weld 43 is provided with a first groove 434 with an upward opening, and the lower end of the calibration weld 43 is provided with a second groove 435 with a downward opening.

[0044] Specifically, the angle gain correction and time gain correction of the phased array excitation transverse or longitudinal wave fan-shaped scan detection sensitivity are completed on the contrast test block 4. The sensitivity is set in the way of angle gain correction and time gain correction. The sensitivity is set on the contrast test block according to the used phased array detector and phased array probe. The reference reflectors used for calibration are the first simulation hole 431, the second simulation hole 432, and the third simulation hole 433. The first simulation hole 431, the second simulation hole 432, and the third simulation hole 433 are all long transverse holes with a diameter of 2 mm. As Figures 2 to 4 shown, the width L of the contrast test block 4 is at least 40 mm. The first simulation hole 431, the second simulation hole 432, and the third simulation hole 433 are all set at the symmetric center of the calibration weld 43 located at the first welding groove and the second welding groove. The height of the austenitic steel block 41 and the martensitic steel block 42 is T. The center of the first simulation hole 431 is located at the T / 4 position, and the first simulation hole 431 is located in the surface layer weld; the center of the second simulation hole 432 is located at the T / 2 position, and the second simulation hole 432 is located in the middle layer weld; the center of the third simulation hole 433 is located at the 3 / 4T position, and the third simulation hole 433 is located in the inner layer weld; the first notch 411, the second notch 412, and the third notch 413 are all hole bodies. The axes of the first notch 411, the second notch 412, and the third notch 413 are all perpendicular to the end face of the first welding groove; the fourth notch 421, the fifth notch 422, and the sixth notch 423 are all hole bodies. The axes of the fourth notch 421, the fifth notch 422, and the sixth notch 423 are all perpendicular to the end face of the second welding groove.

[0045] When using the reference block 4 to calibrate the detection parameters of the surface weld, the main detections are the first groove 434, the first simulated hole 431, the first notch 411, and the fourth notch 421; when using the reference block 4 to calibrate the detection parameters of the middle layer weld, the main detections are the second simulated hole 432, the second notch 412, the fifth notch 422, and the auxiliary detections are the second groove 435, the third simulated hole 433, the third notch 413, and the sixth notch 423; when using the reference block 4 to calibrate the detection parameters of the inner layer weld, the main detections are the third simulated hole 433, the third notch 413, and the sixth notch 423, and the auxiliary detections are the second simulated hole 432, the second notch 412, and the fifth notch 422. Under the calibrated sensitivity, the ratio of the signal amplitude of the artificial reflector of the auxiliary detection object to the signal amplitude of the noise signal is at least 2 times or more, that is, the signal-to-noise ratio is 2:1 or more; the ratio of the signal amplitude of the artificial reflector of the main detection object to the signal amplitude of the noise signal is at least 4 times or more, that is, the signal-to-noise ratio is 4:1 or more. When calibrating the sensitivity of the phased array ultrasonic creeping wave detection, it is carried out using the first groove. Specifically, the size of the first groove is 1mm×1mm, and the detection sensitivity is at least 10dB of the reflection wave amplitude gain of 80% of the first groove.

[0046] In this embodiment, it is necessary to select a suitable ultrasonic phased array detector 5 and a matching signal line before detection to build a weld ultrasonic phased array detection system. The ultrasonic phased array detector 5 should at least have functions of ultrasonic wave emission, reception, amplification, automatic data acquisition, recording, display, and analysis with 32 channels.

[0047] In this embodiment, the processing of the scanning map in step S3 is crucial because, affected by the anisotropy of dissimilar steel welds, there will be inherent echoes at the fusion line between the coarse-grained structure of the weld and the fine-grained base metal; defects have directivity, and different amplitudes will be obtained when scanning on both sides of the dissimilar steel weld. The ultrasonic phased array inspection system can realize the mapping of detection data and can perform post-processing on the generated map. Through image processing techniques such as map flipping, superposition enhancement, and differential averaging, the inherent echo image is removed and shielded, and the defect echo image is enhanced. It should be noted that the starting points of the phased array single-sided double-sided scanning are the same, providing a prerequisite for the superposition enhancement processing of the two-sided maps. Specifically, before detection, the scanning surface of the weld to be measured 3 should be marked, and the marking content should at least include the scanning starting point and the scanning direction. When scanning on both sides of the weld to be measured 3, the starting point, ending point, probe offset distance, and scanning direction of the scanning should all be kept the same, and thus the maps generated by the scanning on both sides of the weld to be measured 3 are obtained respectively. Through the scanning data maps on both sides of the weld to be measured 3 obtained by each scanning mode, one of the maps is horizontally flipped and then superimposed with the other map. Since the inherent echo of the heterogeneous interface only appears at the fusion line between the weld and the steel side, and is more significant at the fusion line between the weld and the fine-grained steel side, a section of it is extracted as a characteristic signal, and differential processing is performed on the entire fusion line to remove and shield the inherent echo signal of the heterogeneous interface. Due to the coarse columnar crystal structure at the center of the weld to be measured and the angle of the defect itself, etc., the amplitudes of the defect echo waves at the same position in the single-sided double-sided scanning are different. The processed defect maps after the two-sided superposition are processed to realize the synthesis and enhancement of the defect maps, improve the contrast of the defect maps, and thus improve the defect detection rate and inspection sensitivity.

[0048] In this embodiment, the angle of the longitudinal wave incident on the ordinary steel / austenitic steel wedge is calculated and selected in the following way: According to Snell's theorem, when α is between the first critical angle α1 and the second critical angle α2, there is only a refracted shear wave in the steel for the longitudinal wave probe. To meet the above requirements, the range of the angle α of the organic glass inclination of the longitudinal wave straight probe special test block is: The first critical angle α1:

[0049] Sinα1 / CL1 = SinβL2 / CL2 = sinβS2 / CS;

[0050] Let βL2 = 90°;

[0051] Sinα1 / 2730 = 1 / 5900;

[0052] α1 = 27.6°, and at this time, the longitudinal wave probe generates creeping waves near the surface of the steel;

[0053] For austenitic steel, Sinα'1 / 2730 = 1 / 5400;

[0054] α'1 = 30.4°, and at this time, the longitudinal wave probe generates creeping waves near the surface of the austenitic steel;

[0055] The second critical angle α2:

[0056] Sinα2 / CL1 = SinβS2 / CS2;

[0057] Let βS2 = 90°;

[0058] Sinα2 / 2730 = 1 / 3230;

[0059] α2 = 57.7°, at this time the longitudinal wave probe generates surface waves on the near surface of the steel;

[0060] Sinα'2 / 2730 = 1 / 3100;

[0061] α'2 = 61.7°, at this time the longitudinal wave probe generates surface waves on the near surface of the austenitic steel;

[0062] Let βS2 = 60°;

[0063] Sinα1 / 2730 = sin60° / 3230;

[0064] α1 = 47°;

[0065] Let βL2 = 55°;

[0066] Sinα1 / 2730 = sin55° / 5900;

[0067] α1 = 22.3°;

[0068] Let βL2 = 80°;

[0069] Sinα1 / 2730 = sin80° / 5900;

[0070] α1 = 27.1°;

[0071] Wherein, α is the inclination angle of the plexiglass; α1 is the first critical angle of the longitudinal wave probe; α2 is the second critical angle of the longitudinal wave probe; β is the refraction angle in steel; βL is the longitudinal wave refraction angle in steel; βS is the shear wave refraction angle in steel; CL1 is the longitudinal wave velocity of plexiglass, 2730 m / s; CS1 is the shear wave velocity of plexiglass, 1460 m / s; CL2 is the longitudinal wave velocity of steel, m / s; CS2 is the shear wave velocity of steel, m / s. For ordinary steel, when the inclination angle α of the plexiglass is less than 27.6°, both longitudinal waves and shear waves are refracted by the longitudinal wave probe in steel; when the inclination angle α of the plexiglass is 27.6°, creeping waves are generated by the longitudinal wave probe near the surface of the steel; when the inclination angle α of the plexiglass is between 27.6° and 57.7°, only pure shear waves are refracted by the longitudinal wave probe in steel. For austenitic steel, when the inclination angle α of the plexiglass is less than 30.4°, both longitudinal waves and shear waves are refracted by the longitudinal wave probe in austenitic steel; when the inclination angle α of the plexiglass is 30.4°, creeping waves are generated by the longitudinal wave probe near the surface of the austenitic steel; when the inclination angle α of the plexiglass is between 30.4° and 61.7°, only pure shear waves are refracted by the longitudinal wave probe in austenitic steel.

[0072] In summary, for the ultrasonic phased array inspection method of the present invention, by using the phased array detection system and the developed special comparison test block, aiming at different positions and different nature defects of the weld to be tested, the thickness stratification detection is carried out by using the single-sided double-sided full direct wave multi-mode optimization parameter scanning detection technology, and the maps obtained by multi-mode double-sided scanning are subjected to superposition enhancement processing, removing and shielding the inherent echo map signals of the heterogeneous interface, synthesizing and enhancing the defect map signals, and solving the problems existing in the conventional ultrasonic detection of austenitic coarse-grained steel welds, such as large sound velocity deviation, difficult defect positioning, serious ultrasonic attenuation, large scattering echo interference, existence of inherent echo of heterogeneous interface, low signal-to-noise ratio, etc.

[0073] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can still be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. An ultrasonic phased array inspection method for welds, used to detect the open defects of the weld to be tested (3) between austenitic steel pipes (1) and martensitic steel pipes (2), characterized in that, It includes the following steps: Step S1: Divide the weld to be measured (3) into a surface weld, a middle weld, and an inner weld arranged in sequence from outside to inside along the thickness direction of the weld to be measured (3); Step S2: Adopt a single-sided double-sided detection method, and use a phased array detector (5) to scan the surface weld, the middle weld, and the inner weld respectively to obtain a surface weld scan pattern, a middle weld scan pattern, and an inner weld scan pattern; When scanning the surface weld, creep wave is used, when scanning the middle weld, transverse wave is used, and when scanning the inner weld, longitudinal wave is used; Step S3: Horizontally flip one side pattern of the surface weld scan data pattern and then superimpose it on the other side pattern of the surface weld scan data pattern; Horizontally flip one side pattern of the middle weld scan data pattern and then superimpose it on the other side pattern of the middle weld scan data pattern; Horizontally flip one side pattern of the inner weld scan data pattern and then superimpose it on the other side pattern of the inner weld scan data pattern; Among them, before detection, marks are made on the scan surface of the weld to be measured (3), and the marked content includes at least the scan starting point and the scan direction. When scanning both sides of the weld to be measured (3), the scan starting point, the termination point, the probe offset distance, and the scan direction are all kept consistent, so as to obtain the patterns generated by scanning both sides of the weld to be measured (3). By horizontally flipping one side pattern of the scan data patterns of both sides of the weld to be measured (3) obtained by each scan mode and then superimposing it on the other side pattern, the defect patterns are synthesized and enhanced, realizing the shielding of interference signals and the enhancement of defect signals.

2. The ultrasonic phased array inspection method for weld seams according to claim 1, characterized in that, In the step S2, the surface weld, the middle weld, and the inner weld are detected by adopting the full direct wave fan-shaped scan method.

3. The ultrasonic phased array inspection method for weld seams according to claim 2, characterized in that, In the step S2, a first wedge block is used to detect the surface weld on both sides of the weld to be measured, and the angle of the first wedge block is greater than or equal to 27° and less than or equal to 37°.

4. The ultrasonic phased array inspection method for weld seams according to claim 2, characterized in that In the step S2, when scanning the middle weld, the fan-shaped scan angle is greater than or equal to 40° and less than or equal to 72°.

5. The ultrasonic phased array inspection method for weld seams according to claim 2, characterized in that, In the step S2, a third wedge block is used to detect the inner weld on both sides of the weld to be measured, and the angle of the third wedge block is greater than or equal to 22.3° and less than or equal to 27.1°.

6. The ultrasonic phased array inspection method for weld seams according to claim 1, characterized in that, In the step S2, the phased array is used to excite the transverse wave to scan the bottom opening defect of the inner weld.

7. The ultrasonic phased array inspection method for weld seams according to claim 1, characterized in that, Before the step S1, it further includes: Step S0: Use a reference block (4) to calibrate the sensitivity of the ultrasonic phased array detection system. The reference block (4) includes an austenitic steel block (41) and a martensitic steel block (42) horizontally welded to the end of the austenitic steel block (41). The weld between the austenitic steel block (41) and the martensitic steel block (42) forms a calibration weld (43), and the structure of the calibration weld (43) is the same as the structure of the weld to be measured (3); The welding end of the austenitic steel block (41) is provided with a first welding groove, and a first notch (411), a second notch (412) and a third notch (413) are arranged at the end face of the first welding groove. The first notch (411) is located in the surface weld; the second notch (412) is located in the middle weld; the third notch (413) is located in the inner weld; The welding end of the martensitic steel block (42) is provided with a second welding groove, and a fourth notch (421), a fifth notch (422) and a sixth notch (423) are arranged at the end face of the second welding groove. The fourth notch (421) is located in the surface weld, the fifth notch (422) is located in the middle weld, and the sixth notch (423) is located in the inner weld.

8. The ultrasonic phased array inspection method for welds according to claim 7, characterized in that The first notch (411), the second notch (412) and the third notch (413) are arranged at intervals from back to front in sequence; the fourth notch (421), the fifth notch (422) and the sixth notch (423) are arranged at intervals from back to front in sequence.

9. The ultrasonic phased array inspection method for welds according to claim 7, characterized in that The middle part of the calibration weld (43) is provided with a first simulation hole (431), a second simulation hole (432) and a third simulation hole (433) which are arranged at intervals from top to bottom in sequence; the first simulation hole (431), the second simulation hole (432) and the third simulation hole (433) all extend in the front-back direction; the first simulation hole (431) is located in the surface weld; the second simulation hole (432) is located in the middle weld, and the third simulation hole (433) is located in the inner weld.

10. The ultrasonic phased array inspection method for weld seams according to claim 7, characterized in that, The upper end of the calibration weld (43) is provided with a first groove (434) with an upward opening, and the lower end of the calibration weld (43) is provided with a second groove (435) with a downward opening.

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