A pipe end flaw detection method, device and medium based on double magnetic head circumferential open circuit magnetization

Abstract

The application discloses a kind of based on double magnetic head circumferential open circuit magnetization pipe end flaw detection method, equipment and medium, it is related to pipe end magnetic particle flaw detection technical field, including, according to double magnetic head magnetic circuit fingerprint chain, magnetic circuit transmission response is carried out slowly variable migration screening, obtains end edge background response, position stable screening is carried out to local abnormal response, obtains defect sensitive response, according to end edge background response adjustment double magnetic head pulsation current proportion, form compensation magnetic field, and positive and negative perturbation back-check is carried out to compensation magnetic field, form low background defect magnetization spectrum;Low background defect magnetization spectrum is carried out circumferential magnetization and is connected, and match double magnetic head pulsation current state maintains circumferential open circuit magnetization, to pipe end inner surface and outer surface apply fluorescent magnetic suspension, form pipe end magnetic trace distribution;Pipe end magnetic trace distribution is carried out circumferential flattening and is connected, forms pipe end magnetic trace development chart.The application improves pipe end defect positioning continuity and accuracy.

Description

Technical Field

[0001] This invention relates to the field of magnetic particle testing technology for pipe ends, and in particular to a pipe end testing method, equipment and medium based on dual magnetic head circumferential open-circuit magnetization. Background Technology

[0002] Existing pipe end magnetic particle inspection technology typically involves circumferentially magnetizing the pipe end using a magnetic yoke or coil, applying fluorescent magnetic suspension to the inner and outer surfaces of the pipe end, and then using intelligent sensors to acquire magnetic response and fluorescent magnetic trace images. Surface or near-surface defects such as cracks are identified by the brightness, morphology, and circumferential distribution of the magnetic traces. With the development of non-contact magnetization, digital image unfolding, and automatic positioning technologies, pipe end inspection has gradually shifted from manual observation to a detection method that combines magnetization parameter control, magnetic response acquisition, and image interpretation, thereby improving the automation level of continuous pipe end inspection and defect location recording.

[0003] In the existing circumferential magnetization process, the end edge of the tube, the curvature of the inner and outer surfaces, and the open state of the magnetic circuit will jointly change the magnetic flux transmission path. Usually, the magnetic trace is maintained by increasing the magnetization intensity or using fixed compensation parameters. However, in scenarios where the geometric features of the tube end change circumferentially, the positions of the two magnetic heads shift continuously, or the magnetic circuits on the inner and outer surfaces are unevenly loaded, the background response of the end edge is easily superimposed with the response of local defects. This is because it is difficult to distinguish between the background response that migrates synchronously with the magnetic circuit transmission and the local abnormal response that remains at the same circumferential position of the tube end with the fixed magnetization parameters. This affects the stable preservation of the defect-sensitive response and the consistency of subsequent magnetic trace positioning. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a tube end flaw detection method based on dual-head circumferential open-circuit magnetization to solve the problem of the difficulty in stably separating the end edge background response and defect response during tube end circumferential open-circuit magnetization.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a pipe end flaw detection method based on dual-head circumferential open-circuit magnetization, comprising: The geometric features of the pipe end to be tested are collected, and the magnetization range of the pipe end is defined based on these features. The dual magnetic heads are then adapted for non-contact magnetization to obtain the open-circuit magnetization bearing position. This bearing position is used to sequentially position the magnetization range around the pipe end, resulting in a circumferential magnetization reference. Based on this reference, the amplitude of the pulsating current is interchanged between the dual magnetic heads to generate a first bias magnetic response and a second bias magnetic response. The two sets of bias magnetic responses are then subjected to response migration and current splitting to obtain the magnetic circuit transmission response and local abnormal response. These responses are then encapsulated according to the circumferential position of the pipe end, forming a dual-head magnetic circuit fingerprint chain. Based on this fingerprint chain, the magnetic circuit transmission response is subjected to gradual migration screening to obtain the edge background response, and the local abnormal response is subjected to position stabilization. The defect-sensitive response is obtained by screening. The ratio of the dual-head pulsating current is adjusted according to the edge background response to form a compensating magnetic field. The compensating magnetic field is then subjected to forward and reverse micro-perturbation verification to form a low-background defect magnetization spectrum. The low-background defect magnetization spectrum is then circumferentially magnetized and connected, and the circumferential open-circuit magnetization is maintained by matching the dual-head pulsating current state. Fluorescent magnetic suspension is applied to the inner and outer surfaces of the tube end to form a magnetic trace distribution at the tube end. The magnetic trace distribution at the tube end is then circumferentially flattened and connected to form a magnetic trace development map at the tube end. The defect location verification is performed on the magnetic trace development map at the tube end to generate a tube end defect location list. The tube end demagnetization status is then verified according to the tube end defect location list to obtain a residual magnetism verification status table. The tube end defect location list and the residual magnetism verification status table are then packaged together to generate a tube end flaw detection report.

[0007] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the method for obtaining the circumferential magnetization reference at the pipe end is as follows: The intelligent sensor continuously scans the inner and outer surfaces of the pipe end to be tested, locates the pipe end face boundary and the pipe wall extension direction, axially aligns and circumferentially connects the scanning position, moves out of the position beyond the pipe end detection area, and forms the pipe end geometric features. Based on the geometric characteristics of the pipe end, the coverage area to be magnetized is delineated along the inner and outer surfaces of the pipe end, and the continuity of the coverage is checked along the circumference of the steel pipe. Any uncovered positions are then filled in to form the magnetization range of the pipe end. Based on the magnetization range of the tube end, the dual magnetic heads are adapted to non-contact magnetization positions, and the dual magnetic heads and the tube end wall are connected to the same circumferential open-circuit magnetization path to obtain the tube end open-circuit magnetization bearing position. Based on the open-circuit magnetization bearing position at the pipe end, the dual magnetic heads are matched segment by segment with the magnetization range at the pipe end along the circumference of the steel pipe, and arranged circumferentially in the order of continuous connection between the previous position and the next position to obtain the circumferential magnetization reference at the pipe end.

[0008] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the generation of the first bias magnetic response and the second bias magnetic response are specifically as follows: Based on the circumferential magnetization reference at the tube end, the pulse current amplitude difference is configured for the dual magnetic heads at the same circumferential position at the tube end, and the magnetic response is continuously collected along the circumferential open-circuit magnetization path by the intelligent sensor, and connected with the current circumferential position at the tube end to generate the first bias magnetic response. Based on the first bias magnetic response, the amplitude of the pulsating current of the dual magnetic heads at the same circumferential position of the tube end is interchanged. The magnetic response is then collected again by the intelligent sensor in the same acquisition sequence as the first bias magnetic response. The newly acquired magnetic response is then connected to the same circumferential position of the tube end to generate the second bias magnetic response.

[0009] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the formation of the dual-head magnetic circuit fingerprint chain is specifically as follows: Align the first bias magnetic response and the second bias magnetic response one by one according to the same tube end circumferential position, and check the tube end circumferential position change between the first bias magnetic response and the second bias magnetic response. The magnetic response that migrates synchronously along the circumferential open-circuit magnetization path as the amplitude of the dual magnetic head pulsating current is interchanged is migrated and continued. The magnetic response that remains at the same tube end circumferential position before and after the pulsating current amplitude is interchanged is stably retained to form the bias magnetic response migration relationship. Based on the bias magnetic response migration relationship, the magnetic response that migrates synchronously along the circumferential open-circuit magnetization path as the amplitude of the dual magnetic head pulsating current is interchanged is divided into the magnetic circuit transmission response. The magnetic response that remains at the same tube end circumferential position before and after the amplitude of the pulsating current is interchanged is divided into the local abnormal response. The magnetic circuit transmission response and the local abnormal response are then separated into positions to form a magnetic response separation spectrum. Based on the magnetic response distribution spectrum, the magnetic circuit transmission response and local abnormal response corresponding to the first bias magnetic response and the second bias magnetic response are encapsulated in the circumferential direction. The magnetic circuit transmission response is sequentially connected along the circumferential direction of the tube end, and the circumferential position of the tube end corresponding to the local abnormal response is retained to form a dual magnetic head magnetic circuit fingerprint chain.

[0010] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the defect-sensitive response is obtained as follows: Based on the dual-head magnetic circuit fingerprint chain, the magnetic circuit transmission response and local abnormal response of the co-encapsulated magnetic circuit are separated item by item along the circumferential direction of the tube end. The magnetic circuit transmission response is continuously expanded according to the circumferential sequence in the dual-head magnetic circuit fingerprint chain. The local abnormal response is retained at the corresponding circumferential position of the tube end. The magnetic circuit transmission response and local abnormal response are circumferentially separated to form a magnetic response circumferential separation spectrum. Based on the circumferential distribution spectrum of the magnetic response, the magnetic circuit transmission response is subjected to gradual migration screening. The magnetic circuit transmission response that changes continuously along the circumferential direction of the tube end is retained as the end edge background response. The magnetic circuit transmission response with interrupted change and local abrupt change is removed, and the local abnormal response at the corresponding circumferential position of the tube end is retained to form the background abnormal distribution spectrum. Based on the background anomaly distribution spectrum, the local anomaly responses are screened for positional similarity. Local anomaly responses that correspond to the same circumferential position at the pipe end in the first bias magnetic response and the second bias magnetic response and do not migrate with the end edge background response are retained to obtain the defect-sensitive response.

[0011] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the formation of a low-background defect magnetization spectrum is specifically as follows: Based on the edge background response and defect-sensitive response, the ratio of the dual magnetic head pulsating current is adjusted in reverse compensation to retain the adjustment state in which the edge background response is reduced but the defect-sensitive response is not reduced synchronously, thus forming a compensation magnetic field. The compensation magnetic field is subjected to positive and negative perturbation verification. The positive and negative perturbation verification refers to the magnetic response that changes synchronously with the perturbation of the compensation magnetic field being back-attached to the edge background response, forming positive and negative perturbations. The local abrupt response that still corresponds to the same circumferential position of the tube end under the positive and negative perturbations is retained as the defect-sensitive response, forming a low-background defect magnetization spectrum.

[0012] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the formation of the pipe end magnetic trace unfolding diagram is specifically as follows: The defect-sensitive response and edge background response corresponding to each tube end circumferential position are extracted along the low background defect magnetization spectrum. The magnetization holding interval is divided into the positions corresponding to the defect-sensitive response, and the magnetization transition interval is divided into the positions corresponding to the edge background response. The current receiving state is configured according to the pulsating current change relationship between adjacent intervals to form a circumferential magnetization receiving sequence. The circumferential magnetization bearing sequence is regulated by pulsed current, and the circumferential movement position of the dual magnetic heads is checked against the corresponding bearing position in the circumferential magnetization bearing sequence item by item. The circumferential movement position that deviates from the open-circuit magnetization bearing position at the tube end is moved back to form a circumferential open-circuit magnetization state chain. Based on the circumferential open-circuit magnetization state chain, the circumferential movement position of the dual magnetic heads is synchronously correlated with the spraying position of the fluorescent magnetic suspension. The fluorescent display areas on the inner and outer surfaces of the tube end are collected, continuous magnetic traces are extracted along the boundary of the fluorescent display area, the spraying coverage interruption position is located and the fluorescent magnetic suspension is replenished to form the tube end magnetic trace distribution. Based on the distribution of magnetic traces at the tube end, fluorescent magnetic trace images of the inner and outer surfaces of the tube end are continuously located. Arc distortion correction is performed on the fluorescent magnetic trace images, and overlapping magnetic traces are eliminated for adjacent fluorescent magnetic trace images. The inner and outer surface images of the tube end are unfolded to the same circumferential position reference of the tube end to form a unfolded magnetic trace map of the tube end.

[0013] As a preferred embodiment of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization described in this invention, the generation of the pipe end flaw detection report is specifically as follows: Fluorescent magnetic trace images are extracted from the unfolded image of the magnetic traces at the pipe end. By locating the circumferential position of the pipe end corresponding to the fluorescent magnetic trace image, the magnetic trace positions that are connected to each other in the circumferential position of adjacent pipe ends are connected. Repeated magnetic traces in the overlapping area of ​​the image are removed to form a set of candidate positions for pipe end defects. The magnetic trace response isotope verification is performed on the candidate location set of pipe end defects. The magnetic trace response isotope verification means that the circumferential location of the pipe end is checked item by item with the defect sensitive response in the low background defect magnetization spectrum, the candidate location of the pipe end defect corresponding to the same circumferential location of the pipe end is retained, the location that only corresponds to the edge background response is removed, and a list of pipe end defect locations is generated. Based on the circumferential position of the pipe end in the pipe end defect location list, the magnetization range of the pipe end is demagnetized by alternating decay. The magnetic response before and after demagnetization is checked item by item. For the position where the magnetic response after demagnetization exceeds the allowable range of residual magnetism, alternating decay demagnetization is continued until the magnetic response within the magnetization range of the pipe end falls within the allowable range of residual magnetism, and the residual magnetism check status table is obtained. The pipe end defect location list and the residual magnetism check status table are circumferentially encapsulated, and the pipe end defect location, the inner surface and outer surface of the pipe end, and the corresponding residual magnetism check status are all assigned to the same circumferential position of the pipe end, generating a pipe end flaw detection report.

[0014] In a second aspect, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, it implements any step of the tube end flaw detection method based on dual magnetic head circumferential open-circuit magnetization as described in the first aspect of the present invention.

[0015] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the tube end flaw detection method based on dual-head circumferential open-circuit magnetization as described in the first aspect of the present invention.

[0016] The beneficial effects of this invention are as follows: By using intelligent sensors to continuously collect bias magnetic responses before and after the amplitude of the dual magnetic head pulsating current is interchanged, and based on the difference in the magnetic response migrating along the circumferential open-circuit magnetization path or maintaining the same circumferential position at the tube end as the amplitude of the pulsating current is interchanged, the magnetic circuit transmission response and the local abnormal response are separated, and a dual magnetic head magnetic circuit fingerprint chain is formed along the circumference of the tube end. This provides a positional basis for screening the end edge background response and retaining the defect-sensitive response, reduces the interference of the end edge geometric magnetization background on the local magnetic trace manifestation, and achieves the effect of improving the continuity and accuracy of tube end defect location. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a pipe end flaw detection method based on dual-head circumferential open-circuit magnetization.

[0019] Figure 2 This is a flowchart illustrating the formation of a dual-head magnetic circuit fingerprint chain.

[0020] Figure 3 This is a flowchart illustrating the formation of a low-background defect magnetization spectrum.

[0021] Figure 4 A flowchart for generating a pipe end flaw detection report. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Reference Figures 1-4This is one embodiment of the present invention, which provides a pipe end flaw detection method based on dual-head circumferential open-circuit magnetization, including the following steps: S1: Collect the geometric features of the pipe end of the steel pipe to be tested, define the magnetization range of the pipe end based on the geometric features of the pipe end, and perform non-contact magnetization position adaptation of the dual magnetic heads to obtain the open-circuit magnetization bearing position of the pipe end. The circumferential magnetization range of the pipe end is sequentially positioned through the open-circuit magnetization bearing position of the pipe end to obtain the circumferential magnetization reference of the pipe end.

[0026] S1.1: The intelligent sensor continuously scans the inner and outer surfaces of the pipe end to be inspected, locates the pipe end face boundary and the pipe wall extension direction, axially aligns and circumferentially connects the scanning position, moves out of the position beyond the pipe end detection area, and forms the pipe end geometric features.

[0027] A smart sensor is a detection device used to continuously collect the surface profile, scanning position, and magnetic response of the inner and outer surfaces and bevels of the pipe end, and output the surface profile, scanning position, and magnetic response according to the same collection time point and the circumferential position of the pipe end.

[0028] Furthermore, the intelligent sensor takes the end face of the steel pipe to be inspected as the starting position for scanning. The scanning end moves continuously along the inner and outer surfaces of the pipe end. During the axial movement, it synchronously records the changes in surface contour and scanning position, and transfers the scanning trajectory successively along the circumference of the steel pipe. Adjacent scanning trajectories retain some overlapping areas. When the scanning trajectory crosses the end face of the pipe, it marks the position of contour change. It continuously tracks the position of contour continuation along the extension direction of the pipe wall. The boundary of the end face of the pipe is locked by the position of contour change, and the extension direction of the pipe wall is locked by the direction of continuous extension of the contour.

[0029] Using the pipe end face boundary as the axial alignment reference, the scanning positions of the inner and outer surfaces of the pipe end are reconnected to the same axial starting point along the pipe wall extension direction. The scanning positions before the axial starting point and outside the pipe end detection area are moved out. Then, the overlapping areas of adjacent scanning trajectories are checked according to the circumferential relationship of the steel pipe. The positions corresponding to the same surface contour in the overlapping area are connected to each other. For the circumferentially broken positions, the adjacent scanning trajectories are called to fill in the gaps until the scanning positions of the inner and outer surfaces of the pipe end are continuously closed along the circumferential direction, forming the geometric features of the pipe end.

[0030] It should be noted that the pipe end geometric features are the geometric positional content formed by the intelligent sensor after continuously scanning the inner and outer surfaces of the pipe end of the steel pipe to be tested, axially aligning and circumferentially connecting the pipe end face boundary, the pipe wall extension direction, and each scanning position. It is used to characterize the axial start and end range of the pipe end detection area, the extension direction of the inner and outer surfaces of the pipe end, and the continuous correspondence along the circumference of the steel pipe, and serves as the basis for subsequently defining the pipe end magnetization range and adapting the non-contact magnetization position of the dual magnetic heads.

[0031] S1.2: Based on the geometric characteristics of the pipe end, delineate the coverage area to be magnetized along the inner and outer surfaces of the pipe end, check the continuity of the coverage along the circumference of the steel pipe, and fill in any uncovered positions to form the magnetization range of the pipe end.

[0032] Furthermore, using the pipe end face boundary and the pipe wall extension direction in the pipe end geometry as limits, the scanning positions are extended axially along the inner and outer surfaces of the pipe end to the steel pipe, respectively. The surface positions located within the pipe end detection area that can be covered by the dual magnetic heads are retained, and the scanning positions that exceed the pipe end face boundary, deviate from the pipe wall extension direction, or cannot be accessed by the inner and outer surfaces of the pipe end are removed. Then, the retained positions are connected segment by segment along the circumference of the steel pipe, so that the start and end positions of the coverage of the inner and outer surfaces of the pipe end correspond to each other, thus defining the coverage area that needs to be magnetized.

[0033] The coverage area to be magnetized is checked item by item along the circumference of the steel pipe. The end position of the previous coverage position is compared with the start position of the next coverage position. If the two positions can be continuously connected, the original coverage relationship is retained. If there is a gap between the two positions, the scanning position of the corresponding inner or outer surface of the pipe end is retrieved from the geometric features of the pipe end, and the gap position is connected to the adjacent coverage position. The circumferential continuity of the filling position is checked again until the coverage area of ​​the inner and outer surfaces of the pipe end is continuously closed along the circumference of the steel pipe, forming the magnetization range of the pipe end.

[0034] S1.3: Based on the magnetization range of the tube end, the dual magnetic heads are adapted to non-contact magnetization positions, and the dual magnetic heads and the tube end wall are connected to the same circumferential open-circuit magnetization path to obtain the tube end open-circuit magnetization bearing position.

[0035] Furthermore, the inner and outer surface coverage positions of the tube end within the tube end magnetization range are defined as boundaries. The two magnetizing ends of the dual magnetic heads are moved to the inner and outer surface sides of the tube end corresponding to the same circumferential position, respectively, so that the magnetization directions of the two magnetizing ends of the dual magnetic heads are opposite and pass through the corresponding tube end walls, while maintaining a non-contact distance between the two magnetizing ends of the dual magnetic heads and the inner and outer surfaces of the tube end, respectively.

[0036] According to the adapted dual magnetic head positions, the magnetization direction formed by the dual magnetic heads at the same circumferential position at the tube end passes through the tube wall at the tube end and moves segment by segment along the magnetization range at the tube end; when the magnetization termination position of the previous circumferential position at the tube end and the magnetization start position of the next circumferential position at the tube end can be connected to each other, the next circumferential position at the tube end is retained; when there is a break between the two positions, the next circumferential position at the tube end is reverted until the magnetization direction formed by the dual magnetic heads extends continuously along the circumferential range at the tube end, thus obtaining the open-circuit magnetization bearing position at the tube end.

[0037] It should be noted that the circumferential open-circuit magnetization path is a non-closed magnetic flux transmission path formed by the two magnetizing ends of the dual magnetic heads being located on the inner and outer surfaces of the tube end, respectively, and maintaining a non-contact interval with the inner and outer surfaces of the tube end. The magnetization direction passes through the corresponding tube end wall and is formed segment by segment as the dual magnetic heads move along the circumference of the steel tube.

[0038] S1.4: Based on the open-circuit magnetization bearing position at the pipe end, the dual magnetic heads are matched segment by segment with the magnetization range at the pipe end along the circumference of the steel pipe, and arranged circumferentially in the order of continuous connection between the previous position and the next position to obtain the circumferential magnetization reference at the pipe end.

[0039] Furthermore, based on the circumferential open-circuit magnetization path in the open-circuit magnetization bearing position at the pipe end, starting from the starting position of the magnetization range at the pipe end, the dual magnetic heads are moved to the corresponding circumferential position at the pipe end, so that the magnetization direction formed by the dual magnetic heads passes through the pipe wall at the corresponding pipe end; the coverage position in the magnetization range at the pipe end is retrieved segment by segment along the circumference of the steel pipe, and each time a coverage position is retrieved, the dual magnetic heads are moved to the same circumferential position at the pipe end, and the current position of the dual magnetic heads, the corresponding coverage position, and the magnetization direction are connected to the same position, so that each coverage position in the magnetization range at the pipe end corresponds to a magnetization position of the dual magnetic heads.

[0040] According to the circumferential movement sequence of the steel pipe, check the adjacent magnetization positions. When the ending position of the previous magnetization position can be connected with the starting position of the next magnetization position, retain the next magnetization position and continue to move to the next circumferential position of the pipe end. When there is a gap or overlap between the previous magnetization position and the next magnetization position, pull back the next magnetization position along the open-circuit magnetization bearing position of the pipe end until the adjacent magnetization positions are continuous and do not overlap. Then fix all the magnetization positions according to the circumferential sequence of the steel pipe to obtain the circumferential magnetization reference of the pipe end.

[0041] It should be noted that the circumferential magnetization reference at the tube end is a reference for the magnetization position formed by arranging the magnetization positions of the dual magnetic heads within the magnetization range of the tube end in a sequential order along the circumference of the steel pipe. It is used to limit the subsequent circumferential movement sequence of the dual magnetic heads, the position of the pulsating current configuration, and the position of the magnetic response acquisition.

[0042] S2: Based on the circumferential magnetization reference at the tube end, the amplitude of the pulsating current of the dual magnetic heads is interchanged to generate the first bias magnetic response and the second bias magnetic response respectively. The two sets of bias magnetic responses are then subjected to response migration and current splitting to obtain the magnetic circuit transmission response and the local abnormal response. The magnetic heads are then packaged according to the circumferential position of the tube end to form a dual magnetic head magnetic circuit fingerprint chain.

[0043] S2.1: Based on the circumferential magnetization reference at the tube end, the pulse current amplitude difference is configured for the dual magnetic heads at the same circumferential position at the tube end, and the magnetic response is continuously collected along the circumferential open-circuit magnetization path by the intelligent sensor, and connected with the current circumferential position at the tube end to generate the first bias magnetic response.

[0044] The circumferential position of the tube end is a single magnetization position fixed in the circumferential magnetization reference of the tube end according to the circumferential sequence of the steel pipe, which is used to correspond to the positioning of the dual magnetic heads, the configuration of the pulsating current and the acquisition of the magnetic response.

[0045] The circumferential open-circuit magnetization path is a non-closed magnetic flux transmission path formed when the two magnetic heads do not contact the tube end wall, the magnetization direction passes through the tube end wall and continues to form as the two magnetic heads move circumferentially along the steel tube.

[0046] Furthermore, according to the circumferential magnetization reference at the tube end, the two magnetic heads are positioned at the same circumferential position at the tube end, and the two magnetic heads are respectively connected to the corresponding positions of the circumferential open-circuit magnetization path; pulsating currents of different amplitudes are applied to the two magnetic heads respectively, keeping the tube end circumferential position and pulsating current amplitude difference configuration unchanged, completing the preparation for magnetic response acquisition at the current tube end circumferential position, and then switching to the next tube end circumferential position according to the tube end circumferential magnetization reference.

[0047] The intelligent sensor continuously collects the magnetic response of the dual magnetic heads under the configuration of pulsating current amplitude difference along the circumferential open-circuit magnetization path, and associates the magnetic response collected each time with the current circumferential position of the tube end; after the collection of the previous circumferential position of the tube end is completed, the magnetic response of the next circumferential position of the tube end is continued according to the circumferential magnetization reference of the tube end, until the circumferential position of the tube end in the circumferential magnetization reference of the tube end is collected, and the first bias magnetic response is generated.

[0048] It should be noted that the magnetic response is the magnetic field change acquired by the intelligent sensor along the circumferential open-circuit magnetization path. The magnetic response is interconnected with the corresponding circumferential position of the tube end, the pulsating current state of the dual magnetic heads, and the acquisition sequence.

[0049] S2.2: Based on the first bias magnetic response, the amplitude of the pulsating current of the dual magnetic heads at the same circumferential position of the tube end is interchanged. The magnetic response is then collected again by the intelligent sensor in the same acquisition sequence as the first bias magnetic response. The magnetic response collected again is then connected to the same circumferential position of the tube end to generate the second bias magnetic response.

[0050] Furthermore, taking the tube end circumferential position and acquisition sequence corresponding to the first bias magnetic response as a reference, keeping the placement order of the dual magnetic heads in the tube end circumferential magnetization reference and the circumferential open-circuit magnetization path unchanged, the pulsating current amplitude currently received by the two magnetization ends of the dual magnetic heads at the same tube end circumferential position is retrieved, and the pulsating current amplitude received by the two magnetization ends of the dual magnetic heads is swapped with each other, so that the original pulsating current amplitude configuration is exchanged between the two magnetization ends of the dual magnetic heads, and the pulsating current amplitude configuration after the swap is kept unchanged at each tube end circumferential position.

[0051] The intelligent sensor collects the magnetic response again in the order of the tube end circumferential position corresponding to the first bias magnetic response. At each tube end circumferential position, the intelligent sensor collects the magnetic response under the state of interchanged amplitude of the dual magnetic head pulsating current, and reconnects the collected magnetic response to the same tube end circumferential position corresponding to the first bias magnetic response. After the previous tube end circumferential position is collected, the next tube end circumferential position is collected, until all tube end circumferential positions in the tube end circumferential magnetization reference are collected again, generating the second bias magnetic response.

[0052] S2.3: Align the first bias magnetic response and the second bias magnetic response one by one according to the same tube end circumferential position, and check the tube end circumferential position change between the first bias magnetic response and the second bias magnetic response. Transfer and continue the magnetic response that migrates synchronously along the circumferential open-circuit magnetization path as the amplitude of the dual magnetic head pulsating current is interchanged. Stable retain the magnetic response that remains at the same tube end circumferential position before and after the pulsating current amplitude interchanges, forming the bias magnetic response migration relationship.

[0053] Furthermore, the first bias magnetic response and the second bias magnetic response are matched item by item according to the circumferential magnetization reference of the tube end. The magnetic response received at each circumferential position of the tube end in the first bias magnetic response and the magnetic response received at the same circumferential position of the tube end in the second bias magnetic response are placed in the same verification position. When the dual magnetic head is positioned, the dual magnetic head pulsating current amplitude configuration and the intelligent sensor acquisition sequence are consistent, the magnetic response is repeatedly acquired at the same circumferential position of the tube end. The maximum circumferential offset distance formed between the response peak positions of each magnetic response is taken as the allowable deviation range of the response peak position. When the offset of the response peak position before and after the pulsating current amplitude exchange does not exceed the allowable deviation range of the response peak position, it is treated as the same circumferential position of the tube end. When the offset of the response peak position exceeds the allowable deviation range of the response peak position and continuously transfers from the current circumferential position of the tube end to the adjacent circumferential position of the tube end, and the transfer direction corresponds to the direction of the dual magnetic head pulsating current amplitude exchange, it is marked as a magnetic response that migrates synchronously along the circumferential open-circuit magnetization path.

[0054] The magnetic response that migrates synchronously along the circumference of the steel pipe connects the termination position of the migration of the previous pipe end circumferential position with the starting position of the migration of the next pipe end circumferential position. For magnetic responses whose peak position shift before and after the exchange of pulsating current amplitude does not exceed the allowable deviation range of the peak position, the same pipe end circumferential position and corresponding magnetic response are retained until all pipe end circumferential positions in the first bias magnetic response and the second bias magnetic response are checked to form a bias magnetic response migration relationship.

[0055] It should be noted that the bias magnetic response migration relationship is used to record the corresponding content of the magnetic response migration position and the retained position after the first bias magnetic response and the second bias magnetic response are aligned at the same circumferential position at the tube end. This distinguishes between the magnetic response that migrates synchronously along the circumferential open magnetization path and the magnetic response that maintains the same circumferential position at the tube end, providing a basis for forming the magnetic circuit transmission response and the local abnormal response.

[0056] S2.4: Based on the bias magnetic response migration relationship, the magnetic response that migrates synchronously along the circumferential open-circuit magnetization path as the amplitude of the dual magnetic head pulsating current is interchanged is divided into the magnetic circuit transmission response. The magnetic response that remains at the same tube end circumferential position before and after the amplitude of the pulsating current is interchanged is divided into the local abnormal response. The magnetic circuit transmission response and the local abnormal response are then separated into positions to form a magnetic response separation spectrum.

[0057] Furthermore, based on the bias magnetic response migration relationship, the magnetic responses before and after the interchange of pulsating current amplitudes are extracted item by item along the circumferential position of the tube end. For magnetic responses that transfer from the current circumferential position of the tube end to the circumferential position of the adjacent tube end after the interchange and are continuously connected along the circumferential open-circuit magnetization path, the migration start position, migration passage position and migration end position are retained and the response is split into magnetic circuit transmission response. For magnetic responses that correspond to the same circumferential position of the tube end before and after the interchange and do not transfer to the circumferential position of the adjacent tube end, the corresponding circumferential position of the tube end is retained and the response is split into local abnormal response.

[0058] The magnetic circuit transmission response and local abnormal response are arranged according to the circumferential magnetization reference of the tube end. The magnetic circuit transmission response is connected to the corresponding circumferential migration position, and the local abnormal response is connected to the corresponding fixed circumferential position of the tube end. When the same circumferential position of the tube end simultaneously receives two types of magnetic responses, the magnetic circuit transmission response is arranged along the circumferential open-circuit magnetization path, and the local abnormal response is retained in the original circumferential position of the tube end, thus completing the positional separation of the two types of magnetic responses and forming a magnetic response separation spectrum.

[0059] S2.5: Based on the magnetic response distribution spectrum, the magnetic circuit transmission response and local abnormal response corresponding to the first bias magnetic response and the second bias magnetic response are encapsulated in the circumferential direction, and the magnetic circuit transmission response is sequentially connected along the circumferential direction of the tube end, while retaining the circumferential position of the tube end corresponding to the local abnormal response, to form a dual-head magnetic circuit fingerprint chain.

[0060] Based on the magnetic response distribution spectrum, the first bias magnetic response and the second bias magnetic response are located item by item according to the circumferential magnetization reference of the tube end. The magnetic circuit transmission response and the local abnormal response corresponding to the same circumferential position of the tube end are connected to the same circumferential position. The magnetic circuit transmission response is arranged according to the migration direction before and after the pulsating current amplitude is interchanged, and the local abnormal response is retained according to the circumferential position of the tube end that remains unchanged before and after the pulsating current amplitude is interchanged. The two types of magnetic responses are written into the corresponding circumferential positions of the tube end respectively.

[0061] The magnetic circuit transmission responses at each circumferential position of the pipe end are sequentially connected along the circumferential direction of the steel pipe. The migration termination position of the previous circumferential position is continuously connected to the migration start position of the next circumferential position. For positions where the migration direction is broken, the magnetic response distribution spectrum is used to reconnect them to the corresponding circumferential position of the pipe end. Local abnormal responses do not participate in the circumferential migration connection and continue to remain at the corresponding circumferential position of the pipe end until all magnetic circuit transmission responses are continuously arranged along the circumferential direction of the pipe end, forming a dual-head magnetic circuit fingerprint chain.

[0062] It should be noted that the dual-head magnetic circuit fingerprint chain is a magnetic circuit transmission response continuously arranged in the circumferential order of the tube end, and retains the magnetic response chain formed by local abnormal response at the corresponding circumferential position of the tube end. It is used to characterize the change of magnetic circuit transmission under the interchange of the amplitude of the dual-head pulsating current, and to provide a basis for subsequent screening of the edge background response and defect sensitive response.

[0063] S3: Based on the magnetic circuit fingerprint chain of the dual magnetic head, the magnetic circuit transmission response is subjected to slow migration screening to obtain the edge background response. The local abnormal response is subjected to positional screening to obtain the defect sensitive response. The ratio of the dual magnetic head pulsating current is adjusted according to the edge background response to form a compensation magnetic field. The compensation magnetic field is subjected to positive and negative micro-perturbation verification to form a low background defect magnetization spectrum.

[0064] S3.1: Based on the dual-head magnetic circuit fingerprint chain, the magnetic circuit transmission response and local abnormal response of the co-encapsulated magnetic circuit are separated item by item along the circumferential direction of the tube end. The magnetic circuit transmission response is continuously expanded according to the circumferential sequence in the dual-head magnetic circuit fingerprint chain. The local abnormal response is retained at the corresponding circumferential position of the tube end. The magnetic circuit transmission response and local abnormal response are circumferentially separated to form a circumferential separation spectrum of magnetic response.

[0065] Furthermore, following the circumferential sequence of the tube ends in the dual-head magnetic circuit fingerprint chain, the magnetic circuit transmission response and local abnormal response received at the same circumferential position of the tube end are located one by one. The magnetic circuit transmission response that is continuously connected along the circumferential position of adjacent tube ends is extracted from the corresponding circumferential position of the tube end, and the local abnormal response that remains unchanged before and after the pulsating current amplitude is interchanged is left at the original circumferential position of the tube end. When the same circumferential position of the tube end receives both the magnetic circuit transmission response and the local abnormal response, the circumferential positions of the tube ends corresponding to the two types of magnetic responses are retained respectively to avoid mutual mixing during the circumferential connection process.

[0066] The extracted magnetic circuit transmission responses are arranged in the circumferential sequence of the dual-head magnetic circuit fingerprint chain. The magnetic circuit transmission responses received at the previous tube end circumferential position and the magnetic circuit transmission responses received at the next tube end circumferential position are unfolded in sequence. The positions where the circumferential continuity is interrupted are reconnected to the corresponding tube end circumferential positions according to the dual-head magnetic circuit fingerprint chain. Local abnormal responses are not unfolded with the magnetic circuit transmission responses, but remain at the original tube end circumferential positions and are arranged separately from the magnetic circuit transmission responses according to the same tube end circumferential sequence to form a circumferentially distributed magnetic response spectrum.

[0067] S3.2: Based on the circumferential distribution spectrum of the magnetic response, the magnetic circuit transmission response is subjected to gradual migration sieving. The magnetic circuit transmission response that changes continuously along the circumferential direction of the tube end is retained as the end edge background response. The magnetic circuit transmission response with interrupted change and local abrupt change is removed, and the local abnormal response at the corresponding circumferential position of the tube end is retained to form the background abnormal distribution spectrum.

[0068] Furthermore, based on the circumferential distribution spectrum of the magnetic response, the magnetic circuit transmission response is extracted sequentially along the circumferential direction of the tube end. The direction of change of the magnetic circuit transmission response at the current circumferential position of the tube end is checked against the direction of change of the magnetic circuit transmission response at the previous and next circumferential positions of the tube end. When the direction of change of the magnetic response at adjacent circumferential positions of the tube end is consistent and the change in the adjacent magnetic response does not exceed the background fluctuation range, the corresponding magnetic circuit transmission response continues along the circumferential direction of the tube end, and the continuous part is retained as the end edge background response.

[0069] When the direction of magnetic response change at the circumferential position of adjacent tube ends reverses, or when the change in adjacent magnetic response exceeds the background fluctuation range, the corresponding magnetic circuit transmission response will be moved out of the end edge background response continuity range; the background fluctuation range is pre-defined based on the repeated acquisition results of defect-free tube ends under the same dual-head pulsating current state.

[0070] S3.3: Based on the background anomaly distribution spectrum, the local anomaly response is screened for positional similarity. The local anomaly response that corresponds to the same circumferential position of the tube end in the first bias magnetic response and the second bias magnetic response and has not migrated with the end edge background response is retained to obtain the defect sensitive response.

[0071] Furthermore, based on the background anomaly distribution spectrum, the local anomaly responses retained at each tube end circumferential position are retrieved item by item according to the tube end circumferential magnetization reference. The local anomaly responses in the first bias magnetic response and the local anomaly responses in the second bias magnetic response are placed corresponding to the same tube end circumferential position. When both sets of local anomaly responses correspond to the same tube end circumferential position, they are retained. When any set of local anomaly responses is transferred to an adjacent tube end circumferential position, it is moved out of the position co-position screening range.

[0072] The circumferential migration positions of the retained local abnormal responses and the edge background responses are checked one by one. When the edge background response migrates from the current pipe end circumferential position to the adjacent pipe end circumferential position, and the local abnormal response still corresponds to the original pipe end circumferential position, the corresponding local abnormal response is retained. When the local abnormal response migrates with the edge background response to the adjacent pipe end circumferential position, it is removed until all pipe end circumferential positions in the background abnormality distribution spectrum are checked, and the defect sensitive response is obtained.

[0073] S3.4: Based on the edge background response and defect-sensitive response, the ratio of the dual magnetic head pulsating current is adjusted in reverse to retain the adjustment state where the edge background response is reduced but the defect-sensitive response is not reduced synchronously, thus forming a compensation magnetic field.

[0074] The dual-head pulsating current ratio is the corresponding ratio between the amplitudes of the pulsating currents received by the two magnetizing ends of the dual magnetic head at the same circumferential position on the tube end. It is used to limit the distribution of magnetization effect between the two magnetizing ends of the dual magnetic head in the circumferential open-circuit magnetization path.

[0075] The background allowable range is defined based on the edge background response repeatedly acquired from the defect-free tube end under the same dual-head pulsating current state. The range of the edge background response obtained from repeated acquisition is taken as the background allowable range.

[0076] Furthermore, based on the edge background response and defect-sensitive response, the amplitude of the pulsating current received by the two magnetized ends of the dual magnetic head is obtained item by item according to the circumferential position of the tube end, and the response amplitude of the edge background response at the corresponding position of the two magnetized ends of the dual magnetic head is compared; when the edge background response increases towards the position corresponding to one magnetized end, the amplitude of the pulsating current received by the corresponding magnetized end is reduced according to the preset adjustment level, and the amplitude of the pulsating current received by the other magnetized end is increased according to the same preset adjustment level; when the edge background response increases towards the position corresponding to the other magnetized end, the amplitude of the pulsating current received by the two magnetized ends of the dual magnetic head is changed in the opposite direction.

[0077] Each time the pulsating current ratio of the dual magnetic heads is changed, the edge background response and defect-sensitive response before and after the change are collected, and the effective value of the compensation adjustment is calculated according to the following expression: ; In the formula, The sequential numbering of the circumferential positions of the pipe ends. For the first The effective value of compensation adjustment corresponding to the circumferential position of each pipe end; To change the edge background response before altering the ratio of the dual-head pulsating current; To change the edge background response after altering the ratio of the dual-head pulsating current; Defect-sensitive response before changing the ratio of dual-head pulsating current; Defect-sensitive response after changing the ratio of dual-head pulsating current.

[0078] When the effective value of the compensation adjustment is positive and higher than the effective value of the compensation adjustment corresponding to the previous adjustment state, the current dual-head pulsating current ratio is retained; when the effective value of the compensation adjustment does not increase, the previous dual-head pulsating current ratio is restored, and the amplitude of the pulsating current received by the two magnetized ends of the dual-head continues to change according to the preset adjustment level in the opposite direction or after reduction. When the edge background response enters the background allowable range, and the defect sensitivity response after the change is not lower than the defect sensitivity response before the change, the reverse compensation adjustment of the current tube end circumferential position is stopped, and the retained dual-head pulsating current ratio is connected with the corresponding tube end circumferential position to form a compensation magnetic field.

[0079] It should be noted that the expression is used to measure whether each change in the dual-head pulsating current ratio simultaneously reduces the edge background response and preserves the defect-sensitive response. The normalized difference before and after the change in edge background response reflects the degree of background suppression, the relative ratio before and after the change in defect-sensitive response reflects the degree of defect response preservation, and the normalized change in defect-sensitive response is used to limit excessive fluctuations in defect response during the adjustment process. The three parts are multiplied together because if any part is too low, the effective value of the compensation adjustment will be reduced simultaneously, avoiding the retention of the current adjustment state solely based on the reduction in edge background response. This allows for the selection of dual-head pulsating current ratios where the edge background response is suppressed and the defect-sensitive response remains intact and changes minimally.

[0080] S3.5: Perform forward and reverse perturbation verification on the compensation magnetic field, and reattach the magnetic response that changes synchronously with the perturbation of the compensation magnetic field to the edge background response. Retain the local abrupt response that still corresponds to the same circumferential position of the tube end under forward and reverse perturbation as the defect sensitive response, forming a low background defect magnetization spectrum.

[0081] Furthermore, the compensation magnetic field was retrieved item by item in the circumferential order of the tube ends. With the circumferential positions of the two magnetic heads corresponding to the tube ends remaining unchanged, the amplitude of the pulsating current received by one magnetized end was increased first while the amplitude of the pulsating current received by the other magnetized end was decreased simultaneously, and the magnetic response under positive perturbation was collected. Then, the direction of change of the amplitude of the pulsating current of the two magnetized ends was reversed, and the magnetic response under reverse perturbation was collected. Both acquisitions were carried out in the same circumferential position of the tube ends, the same circumferential order, and the same placement of the two magnetic heads, and the two magnetic responses were respectively connected to the corresponding circumferential positions of the tube ends.

[0082] For the same circumferential position of the tube end, the direction of change of magnetic response before and after positive perturbation and before and after negative perturbation are compared respectively. Under positive perturbation, the magnetic response increases with the increase of the amplitude of the pulsating current of a magnetizing end, and under negative perturbation, the corresponding magnetic response decreases with the decrease of the amplitude of the pulsating current of the same magnetizing end, or shows opposite synchronous changes. When the corresponding magnetic response is attached back to the edge background response, the local abrupt response under both positive and negative perturbation is retained at the same circumferential position of the tube end and does not transfer to the circumferential position of the adjacent tube end with the change of the ratio of the dual magnetic head pulsating current. When this response is retained as a defect-sensitive response, a low background defect magnetization spectrum is formed.

[0083] S4: Circumferential magnetization is performed on the low background defect magnetization spectrum, and circumferential open-circuit magnetization is maintained by matching the dual magnetic head pulsating current state. Fluorescent magnetic suspension is applied to the inner and outer surfaces of the tube end to form a magnetic trace distribution at the tube end. The magnetic trace distribution at the tube end is then circumferentially flattened and connected to form a magnetic trace development diagram at the tube end.

[0084] S4.1: Extract the defect-sensitive response and edge background response corresponding to each tube end circumferential position along the low background defect magnetization spectrum, divide the position corresponding to the defect-sensitive response into a magnetization holding interval, divide the position corresponding to the edge background response into a magnetization transition interval, and configure the current receiving state according to the pulsating current change relationship between adjacent intervals to form a circumferential magnetization receiving sequence.

[0085] Furthermore, along the low-background defect magnetization spectrum, the defect-sensitive response and edge background response are retrieved sequentially along the tube end circumferential direction. Adjacent tube end circumferential positions corresponding to consecutive defect-sensitive responses are connected, and the tube end circumferential position where the defect-sensitive response begins to appear is taken as the starting point of the interval, and the tube end circumferential position before the defect-sensitive response stops appearing is taken as the ending point of the interval, thus dividing the magnetization maintenance interval. Adjacent tube end circumferential positions corresponding to consecutive edge background responses are connected in the same way to divide the magnetization transition interval.

[0086] The dual-head pulsating currents received by adjacent magnetization holding intervals and magnetization transition intervals are checked in circumferential order at the tube ends. The current receiving status is used to record how the dual-head pulsating current at the end position of the previous interval is connected to the beginning position of the next interval. When the same pulsating current is received at two positions, the dual-head pulsating current at the end position of the previous interval is continued to the beginning position of the next interval and configured as a holding receiving status. When different pulsating currents are received at two positions, the dual-head pulsating current is switched sequentially from the end position of the previous interval to the beginning position of the next interval, and the pulsating currents before and after the switch are respectively connected to the corresponding circumferential positions at the tube ends and configured as a switching receiving status, forming a circumferential magnetization receiving sequence.

[0087] It should be noted that the current continuity state refers to the continuity of the dual-head pulsating current between adjacent magnetization holding intervals and magnetization transition intervals. This includes the continuity state where the dual-head pulsating current at the end of the previous interval continues directly to the beginning of the next interval, and the switching continuity state where the dual-head pulsating current at the end of the previous interval is gradually switched according to the required pulsating current of the next interval.

[0088] S4.2: Perform pulsed current control on the circumferential magnetization bearing sequence, and check the circumferential movement position of the dual magnetic heads against the corresponding bearing position in the circumferential magnetization bearing sequence item by item. Move and reconnect the circumferential movement position that deviates from the open-circuit magnetization bearing position at the tube end to form a circumferential open-circuit magnetization state chain.

[0089] Furthermore, following the circumferential order of the tube ends in the circumferential magnetization sequence, the pulsating current of the dual magnetic heads received at the end position of the previous interval and the beginning position of the next interval are compared item by item. When the pulsating current of the dual magnetic heads received at the two positions is the same, the pulsating current at the end position of the previous interval is used, and the dual magnetic heads maintain the current pulsating current state as they enter the next interval. When the pulsating current of the dual magnetic heads received at the two positions is not the same, the amplitude of the pulsating current received at the two magnetization ends of the dual magnetic heads is changed according to the pulsating current corresponding to the beginning position of the next interval, and the pulsating current switching is completed at the interval junction.

[0090] Each time the dual magnetic heads move to a circumferential position at the tube end, the circumferential movement position of the dual magnetic heads is aligned with the corresponding bearing position and the tube end open-circuit magnetization bearing position in the circumferential magnetization bearing sequence. When the three positions correspond to the same circumferential position at the tube end, the current position is retained and the next circumferential position at the tube end is continued. When the circumferential movement position of the dual magnetic heads exceeds or does not reach the corresponding bearing position, the pulsating current bearing is paused, and the dual magnetic heads are moved back to the tube end open-circuit magnetization bearing position along the circumference of the steel pipe. Then, the pulsating current is restored according to the corresponding bearing position to form a circumferential open-circuit magnetization state chain.

[0091] S4.3: Based on the circumferential open-circuit magnetization state chain, the circumferential movement position of the dual magnetic heads is synchronously matched with the spraying position of the fluorescent magnetic suspension. The fluorescent display area on the inner and outer surfaces of the tube end is collected, and continuous magnetic traces are extracted along the boundary of the fluorescent display area. The spraying coverage interruption position is located and the fluorescent magnetic suspension is replenished to form the magnetic trace distribution at the tube end.

[0092] Furthermore, the dual magnetic heads are moved sequentially along the tube end in the circumferential open-circuit magnetization state chain. When the dual magnetic heads reach a tube end circumferential position, the fluorescent magnetic suspension spraying position is simultaneously moved to the same tube end circumferential position, and the fluorescent magnetic suspension is sprayed onto the inner and outer surfaces of the tube end respectively. When the dual magnetic heads continue to the next tube end circumferential position, the fluorescent magnetic suspension spraying position is simultaneously continued in the same circumferential direction, maintaining the correspondence between the circumferential movement position of the dual magnetic heads, the fluorescent magnetic suspension spraying position, and the tube end open-circuit magnetization bearing position, and continuously collecting the fluorescence display area on the inner and outer surfaces of the tube end.

[0093] Extract the boundary of each fluorescent display area along the light-dark boundary. Sequentially connect the end position of the boundary of the previous tube end circumferential position with the beginning position of the boundary of the next tube end circumferential position, and retain the magnetic traces that extend continuously across the adjacent tube end circumferential positions. When there is no fluorescence display between adjacent fluorescent display areas, the boundary is broken, or the magnetic traces cannot be continued, take the corresponding tube end circumferential position as the spray coverage interruption position, and spray the fluorescent magnetic suspension again at the corresponding position until the adjacent fluorescent display areas are continuously connected, forming a tube end magnetic trace distribution.

[0094] S4.4: Based on the distribution of magnetic traces at the tube end, continuously locate the fluorescent magnetic trace images of the inner and outer surfaces of the tube end, correct the arc surface distortion of the fluorescent magnetic trace images, and perform overlap deduplication on adjacent fluorescent magnetic trace images. Unfold the inner and outer surface images of the tube end to the same circumferential position reference of the tube end to form a unfolded magnetic trace image of the tube end.

[0095] Furthermore, based on the distribution of magnetic traces at the tube end, the fluorescent display areas on the inner and outer surfaces of the tube end are extracted in chronological order according to the circumferential position of the tube end. The boundaries of continuously extending magnetic traces within the same fluorescent display area are then joined together to form a fluorescent magnetic trace image. Based on the circumferential position of the tube end corresponding to the fluorescent magnetic trace image, the image positions arranged along the curved surface of the tube end are unfolded column by column, while maintaining the circumferential order between each column. The positions of the curved and offset magnetic traces are then reconnected along the corresponding circumferential position of the tube end to complete the curved surface distortion correction.

[0096] Adjacent fluorescent magnetic trace images are sequentially received in the circumferential direction of the tube end. The termination region of the previous fluorescent magnetic trace image is matched with the starting region of the next fluorescent magnetic trace image. When the magnetic trace boundaries, extension directions, and circumferential positions of the tube end in the overlapping region correspond to each other, the magnetic traces in the previous fluorescent magnetic trace image are retained and the repeated magnetic traces in the next fluorescent magnetic trace image are removed. Then, the inner surface image and the outer surface image of the tube end are arranged vertically in the same circumferential position of the tube end to form a tube end magnetic trace unfolding diagram.

[0097] It should be noted that a fluorescent magnetic trace image is a magnetic trace image formed by continuously acquiring fluorescent display areas on the inner or outer surface of the tube end, and retaining the magnetic trace boundaries, extension direction, and corresponding circumferential positions of the tube end in the same image.

[0098] S5: Perform defect location verification on the magnetic trace unfolding diagram of the pipe end, generate a pipe end defect location list, and verify the demagnetization status of the pipe end based on the pipe end defect location list to obtain a residual magnetism verification status table. Package the pipe end defect location list and the residual magnetism verification status table together to generate a pipe end flaw detection report.

[0099] S5.1: Extract the fluorescent magnetic trace image from the unfolded image of the pipe end magnetic trace. By locating the circumferential position of the pipe end corresponding to the fluorescent magnetic trace image, connect the magnetic trace positions that are connected in the circumferential position of adjacent pipe ends, remove the repeated magnetic traces in the overlapping area of ​​the image, and form a set of candidate positions for pipe end defects.

[0100] Furthermore, fluorescent magnetic trace images of the inner and outer surfaces of the pipe end are extracted from the unfolded magnetic trace image of the pipe end. According to the circumferential arrangement order of the pipe end in the unfolded magnetic trace image, the magnetic trace position of each fluorescent magnetic trace image is matched with the same circumferential position of the pipe end. The magnetic trace termination position of the previous fluorescent magnetic trace image and the magnetic trace start position of the next fluorescent magnetic trace image are compared sequentially along the circumferential direction of the pipe end. When the two positions are connected and the magnetic trace extension direction is continuous, the corresponding magnetic trace position is connected as the same candidate position of pipe end defect.

[0101] The overlapping areas of adjacent fluorescent magnetic trace images are checked one by one. When the magnetic traces in the overlapping areas correspond to the same circumferential position of the tube end and the boundary and extension direction of the magnetic traces coincide, the magnetic traces in the previous fluorescent magnetic trace image are retained and the repeated magnetic traces in the subsequent fluorescent magnetic trace image are removed. When the boundary or extension direction of the magnetic traces does not coincide, the corresponding magnetic trace positions are retained respectively, and then the positions of the subsequent magnetic traces are arranged in the circumferential order of the tube end to form a set of candidate positions for tube end defects.

[0102] S5.2: Perform magnetic trace response isotope verification on the candidate location set of pipe end defects, check the circumferential location of the pipe end with the defect sensitive response in the low background defect magnetization spectrum item by item, retain the candidate locations of pipe end defects corresponding to the same circumferential location of the pipe end, remove the locations that only correspond to the edge background response, and generate a list of pipe end defect locations.

[0103] Furthermore, according to the circumferential order of the tube end defect candidate positions in the tube end defect candidate position set, the magnetic trace position corresponding to each tube end defect candidate position is extracted item by item, and the magnetic trace position is matched one by one with the tube end circumferential position in the low background defect magnetization spectrum; when the tube end defect candidate position crosses the adjacent tube end circumferential position, the magnetic trace connection direction is sequentially matched with the crossed tube end circumferential position, and then the defect sensitive response and the edge background response of the corresponding position are compared.

[0104] When a candidate location of a pipe end defect corresponds to the same circumferential location of the pipe end as a defect-sensitive response, the candidate location of the pipe end defect and the corresponding magnetic trace location are retained. When a candidate location of a pipe end defect corresponds only to the edge background response and the corresponding location does not receive a defect-sensitive response, the corresponding candidate location of the pipe end defect is removed. When a candidate location of a pipe end defect spans multiple circumferential locations of the pipe end, the magnetic trace location that is in the same position as the defect-sensitive response is retained, and the magnetic trace location that only corresponds to the edge background response is removed, thus generating a list of pipe end defect locations.

[0105] S5.3: Based on the circumferential position of the pipe end in the pipe end defect location list, perform alternating decay demagnetization on the magnetization range of the pipe end, check the magnetic response before and after demagnetization item by item, and continue to perform alternating decay demagnetization on the positions where the magnetic response after demagnetization exceeds the allowable range of residual magnetism until the magnetic response within the magnetization range of the pipe end falls within the allowable range of residual magnetism, and obtain the residual magnetism check status table.

[0106] Furthermore, following the circumferential sequence of the tube ends within the tube end magnetization range, the dual magnetic heads are sequentially positioned at each tube end circumferential location to acquire the magnetic response before the start of alternating decay demagnetization, and then connected to the corresponding tube end circumferential location. The two magnetization ends of the dual magnetic heads are controlled to alternately change the direction of the pulsating current, and the amplitude of the pulsating current is reduced each time the direction is changed. Pulsating currents with opposite directions and decreasing amplitudes are sequentially applied along the tube end magnetization range. After each round of alternating decay demagnetization is completed, the magnetic response is acquired again according to the same tube end circumferential sequence as before demagnetization.

[0107] The expression for calculating the demagnetization convergence value at the current circumferential position of the pipe end is as follows: ; In the formula, This represents the demagnetization convergence value at the current circumferential position of the tube end; The magnetic response was collected before the start of alternating decay demagnetization; This is the magnetic response collected after the current round of alternating decay demagnetization; The amplitude of the pulsating current at the start of alternating decay demagnetization; The amplitude of the pulsating current used for the current round of alternating decay demagnetization.

[0108] When alternating decay demagnetization begins, a non-zero pulsating current is applied. If no magnetic response is collected before or after demagnetization, the demagnetization convergence value is no longer calculated, and the corresponding circumferential position of the tube end is marked as the position where the residual magnetism meets the standard.

[0109] Place the magnetic response before demagnetization at the same circumferential position of the tube end and the magnetic response after the current round of demagnetization accordingly, and check the magnetic response after the current round of demagnetization against the allowable range of residual magnetism. When the demagnetization convergence value is positive, it indicates that the magnetic response weakens synchronously while the amplitude of the pulsating current decreases, and retain the current alternating decay demagnetization direction and the decreasing order of the pulsating current amplitude. When the demagnetization convergence value is not greater than zero and the magnetic response after demagnetization still exceeds the allowable range of residual magnetism, reduce the amount of reduction of the amplitude of the pulsating current in the next round relative to the amplitude of the current round of pulsating current, and continue to apply pulsating current with alternating directions. When the magnetic response after demagnetization falls into the allowable range of residual magnetism, retain the residual magnetism check status at the corresponding circumferential position of the tube end. When the magnetic response after demagnetization exceeds the allowable range of residual magnetism, reconnect the dual magnetic heads to the corresponding circumferential position of the tube end and continue alternating decay demagnetization until the magnetic response at each circumferential position of the tube end within the tube end magnetization range falls into the allowable range of residual magnetism, and obtain the residual magnetism check status table.

[0110] It should be noted that the allowable range of residual magnetism adopts the repeated sampling method of defect-free tube ends. When the dual magnetic heads stop applying pulsating current, the magnetic response at the circumferential position of each tube end is sampled, and the range of the repeatedly sampled magnetic response is taken as the allowable range of residual magnetism.

[0111] S5.4: Encapsulate the pipe end defect location list and the residual magnetism check status table in a circumferential manner, and attach the pipe end defect location, the inner surface and outer surface of the pipe end, and the corresponding residual magnetism check status to the same circumferential position of the pipe end, and generate a pipe end flaw detection report.

[0112] Furthermore, the pipe end defect locations in the pipe end defect location list are extracted item by item in the circumferential order of the pipe end. Each pipe end defect location is mapped to the same circumferential position of the pipe end in the pipe end magnetic trace unfolding diagram. The pipe end inner surface and pipe end outer surface are distinguished according to the source of the fluorescent magnetic trace image. When the same pipe end defect location simultaneously accepts the pipe end inner surface magnetic trace and the pipe end outer surface magnetic trace, the two surface assignments are retained respectively, and the pipe end defect location and the corresponding surface assignment are assigned to the same circumferential position of the pipe end.

[0113] Following the same circumferential order of the pipe ends, the residual magnetic field verification status in the residual magnetic field verification status table is matched with the pipe end defect location item by item. When the residual magnetic field verification status and the pipe end defect location point to the same circumferential position of the pipe end, the residual magnetic field verification status is connected to the corresponding pipe end defect location. When the pipe end defect location spans adjacent circumferential positions of the pipe end, the residual magnetic field verification status corresponding to each circumferential position of the pipe end is respectively accepted. Then, the pipe end defect location, the attribution of the inner and outer surfaces of the pipe end, and the residual magnetic field verification status are uniformly packaged to generate a pipe end flaw detection report.

[0114] It should be noted that the pipe end flaw detection report is a unified package of inspection output content according to the circumferential position of the pipe end, including the location of the pipe end defect, the attribution of the inner surface and outer surface of the pipe end, and the corresponding residual magnetism check status, which is used to indicate the location of the pipe end defect, the surface corresponding to the defect, and the residual magnetism status after demagnetization.

[0115] This embodiment also provides a computer device applicable to the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as proposed in the above embodiment.

[0116] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0117] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the tube end flaw detection method based on dual-head circumferential open-circuit magnetization as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0118] In summary, this invention achieves the following: intelligent sensors continuously acquire bias magnetic responses before and after the amplitude of the dual-head pulsating current is interchanged. Based on the difference in the magnetic response migration along the circumferential open-circuit magnetization path or the difference in maintaining the same circumferential position at the tube end as the amplitude of the pulsating current is interchanged, the magnetic circuit transmission response and the local abnormal response are separated. Then, a dual-head magnetic circuit fingerprint chain is formed along the circumference of the tube end, providing a positional basis for screening the edge background response and retaining the defect-sensitive response. This reduces the interference of the edge geometric magnetization background on the manifestation of local magnetic traces, thereby improving the continuity and accuracy of tube end defect location.

[0119] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A pipe end flaw detection method based on dual-head circumferential open-circuit magnetization, characterized in that, include: The geometric features of the pipe end of the steel pipe to be tested are collected, the magnetization range of the pipe end is defined based on the geometric features of the pipe end, and the dual magnetic heads are adapted to the non-contact magnetization position to obtain the open-circuit magnetization bearing position of the pipe end. The circumferential magnetization range of the pipe end is sequentially positioned through the open-circuit magnetization bearing position of the pipe end to obtain the circumferential magnetization reference of the pipe end. Based on the circumferential magnetization reference at the tube end, the amplitude of the pulsating current of the dual magnetic heads is interchanged to generate the first bias magnetic response and the second bias magnetic response respectively. The two sets of bias magnetic responses are then subjected to response migration and current shunting to obtain the magnetic circuit transmission response and the local abnormal response. The magnetic heads are then packaged according to the circumferential position of the tube end to form a dual magnetic head magnetic circuit fingerprint chain. Based on the magnetic circuit fingerprint chain of the dual magnetic head, the magnetic circuit transmission response is subjected to slow migration screening to obtain the edge background response. The local abnormal response is subjected to position stabilization screening to obtain the defect sensitive response. The ratio of the dual magnetic head pulsating current is adjusted according to the edge background response to form a compensation magnetic field. The compensation magnetic field is subjected to positive and negative micro-perturbation verification to form a low background defect magnetization spectrum. The low-background defect magnetization spectrum is circumferentially magnetized and connected, and the circumferential open-circuit magnetization is maintained by matching the dual magnetic head pulsating current state. Fluorescent magnetic suspension is applied to the inner and outer surfaces of the tube end to form the magnetic trace distribution at the tube end. The magnetic trace distribution at the tube end is then circumferentially flattened and connected to form the magnetic trace development map at the tube end. Defect location verification is performed on the unfolded magnetic trace map of the pipe end, generating a pipe end defect location list. Based on the pipe end defect location list, the demagnetization status of the pipe end is verified to obtain a residual magnetism verification status table. The pipe end defect location list and the residual magnetism verification status table are packaged together to generate a pipe end flaw detection report.

2. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 1, characterized in that, The circumferential magnetization reference obtained at the tube end is as follows: The intelligent sensor continuously scans the inner and outer surfaces of the pipe end to be tested, locates the pipe end face boundary and the pipe wall extension direction, axially aligns and circumferentially connects the scanning position, moves out of the position beyond the pipe end detection area, and forms the pipe end geometric features. Based on the geometric characteristics of the pipe end, the coverage area to be magnetized is delineated along the inner and outer surfaces of the pipe end, and the continuity of the coverage is checked along the circumference of the steel pipe. Any uncovered positions are then filled in to form the magnetization range of the pipe end. Based on the magnetization range of the tube end, the dual magnetic heads are adapted to non-contact magnetization positions, and the dual magnetic heads and the tube end wall are connected to the same circumferential open-circuit magnetization path to obtain the tube end open-circuit magnetization bearing position. Based on the open-circuit magnetization bearing position at the pipe end, the dual magnetic heads are matched segment by segment with the magnetization range at the pipe end along the circumference of the steel pipe, and arranged circumferentially in the order of continuous connection between the previous position and the next position to obtain the circumferential magnetization reference at the pipe end.

3. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 1, characterized in that, The generation of the first bias magnetic response and the second bias magnetic response is as follows: Based on the circumferential magnetization reference at the tube end, the pulse current amplitude difference is configured for the dual magnetic heads at the same circumferential position at the tube end, and the magnetic response is continuously collected along the circumferential open-circuit magnetization path by the intelligent sensor, and connected with the current circumferential position at the tube end to generate the first bias magnetic response. Based on the first bias magnetic response, the amplitude of the pulsating current of the dual magnetic heads at the same circumferential position of the tube end is interchanged. The magnetic response is then collected again by the intelligent sensor in the same acquisition sequence as the first bias magnetic response. The newly acquired magnetic response is then connected to the same circumferential position of the tube end to generate the second bias magnetic response.

4. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 3, characterized in that, The formation of the dual-head magnetic circuit fingerprint chain is as follows: Align the first bias magnetic response and the second bias magnetic response one by one according to the same tube end circumferential position, and check the tube end circumferential position change between the first bias magnetic response and the second bias magnetic response. The magnetic response that migrates synchronously along the circumferential open-circuit magnetization path as the amplitude of the dual magnetic head pulsating current is interchanged is migrated and continued. The magnetic response that remains at the same tube end circumferential position before and after the pulsating current amplitude is interchanged is stably retained to form the bias magnetic response migration relationship. Based on the bias magnetic response migration relationship, the magnetic response that migrates synchronously along the circumferential open-circuit magnetization path as the amplitude of the dual magnetic head pulsating current is interchanged is divided into the magnetic circuit transmission response. The magnetic response that remains at the same tube end circumferential position before and after the amplitude of the pulsating current is interchanged is divided into the local abnormal response. The magnetic circuit transmission response and the local abnormal response are then separated into positions to form a magnetic response separation spectrum. Based on the magnetic response distribution spectrum, the magnetic circuit transmission response and local abnormal response corresponding to the first bias magnetic response and the second bias magnetic response are encapsulated in the circumferential direction. The magnetic circuit transmission response is sequentially connected along the circumferential direction of the tube end, and the circumferential position of the tube end corresponding to the local abnormal response is retained to form a dual magnetic head magnetic circuit fingerprint chain.

5. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 4, characterized in that, The defect-sensitive response is obtained as follows: Based on the dual-head magnetic circuit fingerprint chain, the magnetic circuit transmission response and local abnormal response of the co-encapsulated magnetic circuit are separated item by item along the circumferential direction of the tube end. The magnetic circuit transmission response is continuously expanded according to the circumferential sequence in the dual-head magnetic circuit fingerprint chain. The local abnormal response is retained at the corresponding circumferential position of the tube end. The magnetic circuit transmission response and local abnormal response are circumferentially separated to form a magnetic response circumferential separation spectrum. Based on the circumferential distribution spectrum of the magnetic response, the magnetic circuit transmission response is subjected to gradual migration screening. The magnetic circuit transmission response that changes continuously along the circumferential direction of the tube end is retained as the end edge background response. The magnetic circuit transmission response with interrupted change and local abrupt change is removed, and the local abnormal response at the corresponding circumferential position of the tube end is retained to form the background abnormal distribution spectrum. Based on the background anomaly distribution spectrum, the local anomaly responses are screened for positional similarity. Local anomaly responses that correspond to the same circumferential position at the pipe end in the first bias magnetic response and the second bias magnetic response and do not migrate with the end edge background response are retained to obtain the defect-sensitive response.

6. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 5, characterized in that, The formation of a low-background defect magnetization spectrum is specifically as follows: Based on the edge background response and defect-sensitive response, the ratio of the dual magnetic head pulsating current is adjusted in reverse compensation to retain the adjustment state in which the edge background response is reduced but the defect-sensitive response is not reduced synchronously, thus forming a compensation magnetic field. The compensation magnetic field is subjected to positive and negative perturbation verification. The positive and negative perturbation verification refers to the magnetic response that changes synchronously with the perturbation of the compensation magnetic field being back-attached to the edge background response, forming positive and negative perturbations. The local abrupt response that still corresponds to the same circumferential position of the tube end under the positive and negative perturbations is retained as the defect-sensitive response, forming a low-background defect magnetization spectrum.

7. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 1 or 6, characterized in that, The unfolded diagram of the magnetic trace at the tube end is as follows: The defect-sensitive response and edge background response corresponding to each tube end circumferential position are extracted along the low background defect magnetization spectrum. The magnetization holding interval is divided into the positions corresponding to the defect-sensitive response, and the magnetization transition interval is divided into the positions corresponding to the edge background response. The current receiving state is configured according to the pulsating current change relationship between adjacent intervals to form a circumferential magnetization receiving sequence. The circumferential magnetization bearing sequence is regulated by pulsed current, and the circumferential movement position of the dual magnetic heads is checked against the corresponding bearing position in the circumferential magnetization bearing sequence item by item. The circumferential movement position that deviates from the open-circuit magnetization bearing position at the tube end is moved back to form a circumferential open-circuit magnetization state chain. Based on the circumferential open-circuit magnetization state chain, the circumferential movement position of the dual magnetic heads is synchronously correlated with the spraying position of the fluorescent magnetic suspension. The fluorescent display areas on the inner and outer surfaces of the tube end are collected, continuous magnetic traces are extracted along the boundary of the fluorescent display area, the spraying coverage interruption position is located and the fluorescent magnetic suspension is replenished to form the tube end magnetic trace distribution. Based on the distribution of magnetic traces at the tube end, fluorescent magnetic trace images of the inner and outer surfaces of the tube end are continuously located. Arc distortion correction is performed on the fluorescent magnetic trace images, and overlapping magnetic traces are eliminated for adjacent fluorescent magnetic trace images. The inner and outer surface images of the tube end are unfolded to the same circumferential position reference of the tube end to form a unfolded magnetic trace map of the tube end.

8. The pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in claim 7, characterized in that, The generated pipe end flaw detection report is as follows: Fluorescent magnetic trace images are extracted from the unfolded image of the magnetic traces at the pipe end. By locating the circumferential position of the pipe end corresponding to the fluorescent magnetic trace image, the magnetic trace positions that are connected to each other in the circumferential position of adjacent pipe ends are connected. Repeated magnetic traces in the overlapping area of ​​the image are removed to form a set of candidate positions for pipe end defects. The magnetic trace response isotope verification is performed on the candidate location set of pipe end defects. The magnetic trace response isotope verification means that the circumferential location of the pipe end is checked item by item with the defect sensitive response in the low background defect magnetization spectrum, the candidate location of the pipe end defect corresponding to the same circumferential location of the pipe end is retained, the location that only corresponds to the edge background response is removed, and a list of pipe end defect locations is generated. Based on the circumferential position of the pipe end in the pipe end defect location list, the magnetization range of the pipe end is demagnetized by alternating decay. The magnetic response before and after demagnetization is checked item by item. For the position where the magnetic response after demagnetization exceeds the allowable range of residual magnetism, alternating decay demagnetization is continued until the magnetic response within the magnetization range of the pipe end falls within the allowable range of residual magnetism, and the residual magnetism check status table is obtained. The pipe end defect location list and the residual magnetism check status table are circumferentially encapsulated, and the pipe end defect location, the inner surface and outer surface of the pipe end, and the corresponding residual magnetism check status are all assigned to the same circumferential position of the pipe end, generating a pipe end flaw detection report.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the pipe end flaw detection method based on dual-head circumferential open-circuit magnetization as described in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the pipe end flaw detection method based on dual magnetic head circumferential open-circuit magnetization as described in any one of claims 1 to 8.

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