Online detection method, system, terminal and medium for reliability of cold-rolled steel strip welded joints

Abstract

The present invention belongs to the technical field of high-end equipment manufacturing, and discloses an online detection method, system, terminal and medium for the reliability of cold-rolled steel strip welded joints, which clarifies the magnetic properties of the material to be tested; clarifies the organizational characteristics of the welded joint to be tested; clarifies the influence of the detection frequency on the impedance signal characteristics; clarifies the influence of the coil voltage on the signal characteristics; clarifies the influence of the probe lifting height on the signal characteristics; clarifies the influence of the scanning speed on the signal characteristics; clarifies the influence of the scanning angle on the signal characteristics; establishes a database of the characteristic defect characteristics of the welded joints, and performs reliability verification. In the online detection method for the reliability of cold-rolled steel strip welded joints provided by the present invention, the method is used to perform non-destructive testing of the online quality reliability of the cold-rolled steel strip joints, avoiding the traditional destructive cupping test and microstructure analysis test, and ensuring the efficient operation of the cold-rolled steel strip production line.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-end equipment manufacturing, and in particular relates to an online detection method, system, terminal and medium for reliability of cold-rolled steel strip welded joints. Background Art

[0002] At present, cold-rolled silicon steel is the main industry of Jiugang. However, the output of high-quality non-oriented silicon steel has always been unable to meet market demand. The problem of silicon steel strip breaking during cold rolling is the main reason restricting the output of silicon steel.

[0003] In view of the characteristics of non-oriented silicon steel production process window being narrow, equipment being complex and production technology being difficult, Jiugang, based on the compact strip steel (CSP) silicon steel production line of Jiugang Carbon Steel Thin Plate Plant, has carried out in-depth invention and technology development of equipment related to silicon steel production, and overcome the common key core technology problems that restrict the development of the silicon steel industry. It is imperative for Jiugang to enhance the competitiveness of core technologies.

[0004] Si has a strong solid solution strengthening effect on α-Fe, which increases the hardness and strength of silicon steel, and reduces plasticity and toughness, which makes the machinability of silicon steel strip drop sharply. In the typical silicon steel strip cold rolling process, strip welding equipment is indispensable, and the leading steel strip and the following steel strip must be welded to ensure the continuous operation of the production line. In traditional MIG, TIG, MAG and other welding methods, the grains of the joints are coarser than those of the parent material, with poor toughness and easy cracking, and the performance of the joints and heat-affected zones is far inferior to that of the parent material. Therefore, the strip cold rolling production line usually uses flash welding with a smaller heat-affected zone to weld silicon steel strips to ensure the quality reliability of the strip joints.

[0005] However, the flash welding of silicon steel strips used in Jiugang CSP production line is still the main location for strip breakage during cold rolling. At the same time, during online cold rolling, the steel strip needs to undergo multiple "S"-shaped bending deformations and withstand a certain operating tension, so the performance and quality requirements of the weld are extremely stringent. The strip breakage rate during the cold rolling process of ordinary low-carbon steel is usually below 0.3%.

[0006] However, for silicon steel, the breakage rate at the weld joint during the cold rolling process increases significantly, and even remains high for a period of time, generally around 1-2%, and can reach around 3-4% in severe cases. After the breakage, the entire cold rolling unit needs to be stopped and the strips need to be re-threaded, which greatly reduces the production efficiency of silicon steel and also affects its product quality.

[0007] Therefore, the inspection of the quality of silicon steel strip welding joints is a key factor restricting the continuous operation of the cold rolling production line. The method currently commonly used in the steel rolling industry is a destructive weld cupping test, which involves multiple steps such as production suspension sampling and organizational analysis. In order to ensure the continuous and stable production of cold-rolled silicon steel, the introduction of eddy current non-destructive testing technology to conduct online monitoring of cold-rolled strip welding joints and predict the reliability of the quality of cold-rolled strip welding joints based on existing data models is currently the most practical and effective way. To this end, for silicon steel strip continuous rolling production lines with narrow welding joint detection windows and wide areas, it is necessary to carry out the design of eddy current detection probes suitable for online monitoring of strip steel, develop prototypes of automated eddy current detection equipment for strip steel production lines, and locate and reconstruct joint defects based on signal characteristics.

[0008] Through the above analysis, the problems and defects of the prior art are as follows:

[0009] (1) The cupping test is used to detect the quality reliability of cold-rolled strip welded joints, which involves stopping production for sampling, seriously affecting production efficiency;

[0010] (2) For cold rolling production lines that undergo large deformation, there is zero tolerance for weld joint defects. The cupping test currently used can only take random samples and cannot guarantee the quality reliability of all welds;

[0011] (3) The cupping test requires repeated and complex mechanical property tests and structural analysis, which requires personnel with relevant professional knowledge to implement.

[0012] The difficulty of solving the above problems and defects is:

[0013] (1) The current nondestructive testing methods can easily identify defects in welded joints, but it is not easy to detect the microstructure;

[0014] (2) The structure of the plate and strip welded joint is complex, resulting in discrete performance. It is difficult to ensure uniform joint structure and performance by simply adjusting process parameters. Therefore, it is best to perform online reliability testing on all welded joints.

[0015] (3) There is a lack of methods to correlate eddy current detection signals with microstructure and performance through measurable and controllable physical characteristic parameters, and it is impossible to effectively establish the correlation between the microstructure, performance and process parameters of cold-rolled steel strip welded joints.

[0016] The significance of solving the above problems and defects is:

[0017] (1) Improve production efficiency and reduce production costs;

[0018] (2) Reduce reliance on the knowledge reserves of on-site operators;

[0019] (3) Improve the quality reliability of welded joints and the uniformity of the structure to ensure the quality reliability of cold-rolled silicon steel strips. Summary of the invention

[0020] In view of the problems existing in the prior art, the present invention provides a method, system, terminal and medium for online detection of reliability of cold-rolled steel strip welded joints.

[0021] The present invention is implemented as follows: an online detection method for reliability of cold-rolled steel strip welded joints comprises the following steps:

[0022] Step 1: clarify the magnetic properties of the material to be tested;

[0023] Step 2: clarify the organizational characteristics of the welded joint to be inspected;

[0024] Step 3: clarify the impact of detection frequency on impedance signal characteristics;

[0025] Step 4: clarify the influence of coil voltage on signal characteristics;

[0026] Step 5: clarify the influence of the probe lifting height on the signal characteristics;

[0027] Step 6: Clarify the impact of scanning speed on signal characteristics;

[0028] Step 7: Clarify the influence of scanning angle on signal characteristics;

[0029] Step eight, establish a characteristic defect organization database for welding joints and conduct reliability verification.

[0030] Furthermore, in step 1, the determining of the magnetic properties of the material to be tested includes:

[0031] The vibrating sample magnetometer VSM is used to measure the magnetic properties of the material to be tested, and the hysteresis loop is obtained. Since the excitation magnetic field of eddy current testing is relatively low, the magnetic permeability is simplified to the average value of the slopes of two fitting straight lines. The magnetic permeability of the material to be tested is obtained by calculation; the magnetic permeability is less than or equal to 1 for non-ferromagnetic materials, and the magnetic permeability is greater than 1 for ferromagnetic materials. Magnetic saturation is performed on ferromagnetic materials.

[0032] Further, in step 2, the determining of the structural characteristics of the weld joint to be inspected includes:

[0033] After analyzing the cold cracking tendency of the steel strip by the cupping test, tensile specimens were taken from the weld joint between the cracking point and the uncracked point of the cupping test; after analyzing the mechanical properties of the characteristic area and the evolution characteristics of the organization during the deformation process, metallographic observation was used to determine the organizational characteristics of the weld area of ​​the cold-rolled steel strip.

[0034] In step 3, the effect of the detection frequency on the impedance signal characteristics is clearly determined, including:

[0035] The detection frequency adjustment range of the eddy current detection host used is 100-1MHz. The inspected materials are welding joints with different characteristic tissues. The excitation coil voltage frequency is 1kHz, 5kHz-50kHz, and the step is 5kHz. The welding joints with different characteristic tissues are inspected to obtain the frequency range in which different characteristic tissues are most sensitive to eddy current signals.

[0036] Further, in step 4, the determining the influence of the coil voltage on the signal characteristics includes:

[0037] The excitation mode of the excitation coil is voltage excitation, and the maximum value is 12V. The optimal detection frequency obtained in step three is selected. When other parameters remain unchanged, the weld joint structure is detected under different excitation coil voltages. The impedance diagram features are extracted for each set of experimental parameters, and the characteristic values ​​are averaged, and a more reasonable excitation voltage is selected from the average values.

[0038] In step 5, the determining of the influence of the probe lift-off height on the signal characteristics includes:

[0039] The detection frequency is set to the optimal detection frequency measured in step three, and the excitation voltage is set to the excitation voltage obtained in step four. The weld joint structure is tested at different lift-off distances in the range of 0.5 to 4 mm. The characteristic values ​​of each group of experimental data are averaged and the optimal lift-off distance is selected.

[0040] Further, in step six, the determining the effect of the scanning speed on the signal characteristics includes:

[0041] The detection frequency is set to the optimal detection frequency measured in step three, the excitation voltage is set to the excitation voltage obtained in step four, and the lift-off height is set to the optimal lift-off distance obtained in step five. The weld joint structure is inspected at different scanning speeds, the characteristic values ​​of each group of experimental data are averaged, and the optimal scanning speed is selected.

[0042] In step 7, the influence of the scanning angle on the signal characteristics is clarified, including:

[0043] The detection frequency is set to the optimal detection frequency measured in step three, the excitation voltage is set to the excitation voltage obtained in step four, the lift-off height is set to the optimal lift-off distance obtained in step five, the scanning speed is the optimal scanning speed obtained in step six, and the reciprocating scanning angles of the probe are set to 0 to 90°, with an angle step of 15°; the organizational characteristics of the welding joint are detected, the impedance characteristics are analyzed, and the angle range with large errors is eliminated.

[0044] Further, in step eight, the establishment of a welding joint characteristic defect characteristic organization database includes:

[0045] Taking the obtained parameters as the optimal parameters, multiple batches of welding joints were selected for testing, and the characteristic parameters of the measured defect-free impedance diagram and the defective impedance diagram were extracted respectively; welding joints with large differences in characteristic parameters were randomly selected for metallographic observation, and a database corresponding to the characteristic defects, characteristic structure and characteristic parameters of welding joints was established; samples were randomly selected from different batches of products for eddy current testing and metallographic observation, and compared and verified with the established database, and a database of the correlation between structure, performance and process parameters was established.

[0046] Another object of the present invention is to provide a cold-rolled steel strip welded joint reliability online detection system using the cold-rolled steel strip welded joint reliability online detection method, the cold-rolled steel strip welded joint reliability online detection system comprising:

[0047] A material magnetic property determination module is used to determine the magnetic properties of the material to be tested;

[0048] Joint structure feature determination module, used to clarify the structure features of the welded joint to be inspected;

[0049] The signal characteristic influence determination module is used to respectively clarify the influence of the detection frequency on the impedance signal characteristics, the influence of the coil voltage on the signal characteristics, the influence of the probe lift-off height on the signal characteristics, the influence of the scanning speed on the signal characteristics, and the influence of the scanning angle on the signal characteristics;

[0050] The feature organization database construction module is used to establish a feature organization database of welding joint feature defects and perform reliability verification.

[0051] Another object of the present invention is to provide a computer device, the computer device comprising a memory and a processor, the memory storing a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0052] Clarify the magnetic properties of the material to be inspected; clarify the organizational characteristics of the weld joint to be inspected; clarify the influence of the detection frequency on the impedance signal characteristics; clarify the influence of the coil voltage on the signal characteristics; clarify the influence of the probe lift-off height on the signal characteristics; clarify the influence of the scanning speed on the signal characteristics; clarify the influence of the scanning angle on the signal characteristics; establish a database of the organizational characteristics of the weld joint defects, and conduct reliability verification.

[0053] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the following steps:

[0054] Clarify the magnetic properties of the material to be inspected; clarify the organizational characteristics of the weld joint to be inspected; clarify the influence of the detection frequency on the impedance signal characteristics; clarify the influence of the coil voltage on the signal characteristics; clarify the influence of the probe lift-off height on the signal characteristics; clarify the influence of the scanning speed on the signal characteristics; clarify the influence of the scanning angle on the signal characteristics; establish a database of the organizational characteristics of the weld joint defects, and conduct reliability verification.

[0055] Another object of the present invention is to provide a cold-rolled silicon steel production line, which is used to implement the online detection method for the reliability of cold-rolled steel strip welded joints.

[0056] Combining all the above technical solutions, the advantages and positive effects of the present invention are as follows:

[0057] (1) In the online detection method for the reliability of cold-rolled steel strip welded joints provided by the present invention, the method is used to perform non-destructive detection of the online quality reliability of cold-rolled steel strip joints, avoiding traditional destructive cupping tests and microstructure analysis tests, and ensuring the efficient operation of the cold-rolled steel strip production line.

[0058] (2) At present, domestic high-quality cold-rolled steel strips of difficult-to-weld metals mainly rely on imports, such as high-silicon steel with a silicon content of 6% used in new energy vehicles. The present invention can achieve stable cold rolling of high-quality difficult-to-weld metals, solve the "bottleneck" link of stable cold rolling of high-quality difficult-to-weld metals, and is of great significance to the realization of industrial upgrading and the integrity of the industrial chain. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0060] Figure 1 It is a flow chart of the online detection method for reliability of cold-rolled steel strip welded joints provided by an embodiment of the present invention.

[0061] Figure 2 This is a structural block diagram of an online detection system for reliability of cold-rolled steel strip welded joints provided by an embodiment of the present invention;

[0062] In the figure: 1. Material magnetic property determination module; 2. Joint tissue feature determination module; 3. Signal feature influence determination module; 4. Feature tissue database construction module.

[0063] Figure 3 It is a schematic diagram of the sampling method for the cupping test and the tensile test provided in the embodiment of the present invention.

[0064] Figure 4 This is a test diagram of the mechanical properties of the silicon steel base material and the silicon steel strip flash welded joint provided by the embodiment of the present invention.

[0065] Figure 4 (a) is a tensile curve diagram provided by an embodiment of the present invention.

[0066] Figure 4 (b) is a schematic diagram of the post-fracture morphology of the sample provided in an embodiment of the present invention.

[0067] Figure 5 It is a schematic diagram of the microstructure of different positions of the flash welded joint of a silicon steel strip provided by an embodiment of the present invention.

[0068] Figure 5 (a) is a schematic diagram of a parent material provided in an embodiment of the present invention.

[0069] Figure 5 (b) is provided by an embodiment of the present invention Figure 4 Schematic diagram of the area between mid-cup positions I and II.

[0070] Figure 5 (c) is a schematic diagram of the area between cupping positions III and IV provided in an embodiment of the present invention.

[0071] Figure 6 It is a schematic diagram of the eddy current detection scanning method and the process of forming the eddy current detection signal impedance diagram.

[0072] Figure 6 (a) When the probe is scanned in the positive X direction directly above the defect, the impedance diagram changes along the trajectory of the OMN.

[0073] Figure 6 (b) shows the impedance diagram changing along the trajectory NLO when the probe continues to scan away from the defect in the positive X direction.

[0074] Figure 6 (c) The scanning mode of the probe is reciprocating scanning.

[0075] Figure 6 (d) After reaching the maximum scanning position, scanning is performed in the negative X direction, and finally an impedance diagram shaped like "8" is formed.

[0076] Figure 7 This is an eddy current detection impedance diagram at different positions of a silicon steel strip flash welded joint provided by an embodiment of the present invention.

[0077] Figure 7 (a) is a schematic diagram of a parent material provided in an embodiment of the present invention.

[0078] Figure 7 (b) is provided by an embodiment of the present invention Figure 4Schematic diagram of the area between mid-cup positions I and II.

[0079] Figure 7 (c) is a schematic diagram of the area between cupping positions III and IV provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0081] In view of the problems existing in the prior art, the present invention provides a method and system for online detection of reliability of cold-rolled steel strip welded joints. The present invention is described in detail below in conjunction with the accompanying drawings.

[0082] like Figure 1 As shown, the online detection method for reliability of cold-rolled steel strip welded joints provided by the embodiment of the present invention comprises the following steps:

[0083] S101, clarify the magnetic properties of the material to be tested;

[0084] S102, clarify the structural characteristics of the welded joint to be inspected;

[0085] S103, clarify the effect of detection frequency on impedance signal characteristics;

[0086] S104, clarify the influence of coil voltage on signal characteristics;

[0087] S105, clarify the effect of probe lift-off height on signal characteristics;

[0088] S106, clarify the effect of scanning speed on signal characteristics;

[0089] S107, clarify the influence of scanning angle on signal characteristics;

[0090] S108, establish a welding joint characteristic defect feature organization database and perform reliability verification.

[0091] like Figure 2 As shown, the cold-rolled steel strip weld joint reliability online detection system provided by the embodiment of the present invention includes:

[0092] Material magnetic property determination module 1, used to determine the magnetic properties of the material to be tested;

[0093] Joint structure characteristic determination module 2, used to determine the structure characteristics of the welded joint to be inspected;

[0094] The signal characteristic influence determination module 3 is used to respectively determine the influence of the detection frequency on the impedance signal characteristic, the influence of the coil voltage on the signal characteristic, the influence of the probe lift-off height on the signal characteristic, the influence of the scanning speed on the signal characteristic, and the influence of the scanning angle on the signal characteristic;

[0095] The feature organization database construction module 4 is used to establish a feature organization database of welding joint feature defects and perform reliability verification.

[0096] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0097] Example 1

[0098] In view of the problems existing in the prior art, the present invention provides a key technology and system for online detection of reliability of cold-rolled steel strip welded joints.

[0099] The present invention is achieved in that:

[0100] A key technology and system for online detection of reliability of cold-rolled steel strip welded joints, comprising the following steps:

[0101] Step 1: Identify the magnetic properties of the material to be tested.

[0102] The vibrating sample magnetometer (VSM) is used to measure the magnetic properties of the material to be tested, and the hysteresis loop is obtained. Since the excitation magnetic field of eddy current testing is relatively low, the magnetic permeability can be simplified to the average value of the slopes of two fitting lines. The magnetic permeability of the material to be tested is obtained by calculation. The magnetic permeability is less than or equal to 1 for non-ferromagnetic materials, and the magnetic permeability is greater than 1 for ferromagnetic materials. Magnetic saturation is performed on ferromagnetic materials.

[0103] Step 2: Clarify the structural characteristics of the weld joint to be inspected.

[0104] The cupping test was used to analyze the cold cracking tendency of the steel strip (see Figure 3 ), and then take tensile specimens from the weld joint between the cracked point and the uncracked point in the cupping test to analyze the mechanical properties of the characteristic area and the evolution characteristics of the organization during the deformation process (see Figure 4 Then metallographic observation was used to determine the structural characteristics of the weld area of ​​the cold-rolled steel strip ( Figure 5 ).

[0105] Step 3: Clarify the effect of detection frequency on impedance signal characteristics.

[0106] The detection frequency adjustment range of the eddy current detection host used in the present invention is 100-1MHz. The inspected materials are welding joints with different characteristic tissues. The excitation coil voltage frequency is 1kHz, 5kHz-50kHz (in steps of 5kHz). The welding joints with different characteristic tissues are inspected to obtain the frequency range in which different characteristic tissues are most sensitive to eddy current signals.

[0107] Step 4: Clarify the effect of coil voltage on signal characteristics.

[0108] The excitation mode of the excitation coil in the present invention is voltage excitation, and the maximum value is 12V. The optimal detection frequency obtained in step 3 is selected. When other parameters remain unchanged, the weld joint structure is detected under different excitation coil voltages. The impedance diagram features are extracted for each group of experimental parameters, and the characteristic values ​​are averaged. A more reasonable excitation voltage is selected from the average values.

[0109] Step 5: Clarify the effect of probe lift-off height on signal characteristics.

[0110] The detection frequency is set to the optimal detection frequency measured in step 3, and the excitation voltage is set to the excitation voltage obtained in step 4. The weld joint structure is tested at different lift-off distances in the range of 0.5-4mm, the characteristic values ​​of each group of experimental data are averaged, and the optimal lift-off distance is selected.

[0111] Step 6: Clarify the impact of scanning speed on signal characteristics.

[0112] The detection frequency is set to the optimal detection frequency measured in step 3, the excitation voltage is set to the excitation voltage obtained in step 4, and the lift-off height is set to the optimal lift-off distance obtained in step 5. The weld joint structure is inspected at different scanning speeds, the characteristic values ​​of each group of experimental data are averaged, and the optimal scanning speed is selected.

[0113] Step 7: Clarify the impact of scanning angle on signal characteristics.

[0114] The detection frequency is set to the optimal detection frequency measured in step 3, the excitation voltage is set to the excitation voltage obtained in step 4, the lift-off height is set to the optimal lift-off distance obtained in step 5, the scanning speed is the optimal scanning speed obtained in step 6, and the reciprocating scanning angle of the probe is set to 0-90° (the angle step is 15°) to detect the organizational characteristics of the weld joint, analyze the impedance characteristics, and eliminate the angle range with large errors.

[0115] Step 8, establish a welding joint characteristic defect feature organization database and verify its reliability.

[0116] Taking the parameters obtained in the above steps as the optimal parameters, multiple batches of welded joints were selected for testing, and the characteristic parameters of the measured impedance diagrams without defects and with defects were extracted respectively. Welded joints with large differences in characteristic parameters were randomly selected for metallographic observation, and a database corresponding to the characteristic defects, characteristic structures and characteristic parameters of welded joints was established. Samples were randomly selected from different batches of products for eddy current testing and metallographic observation, and compared and verified with the established database to establish a database of the correlation between structure, performance and process parameters.

[0117] The method is used for nondestructive testing of the online quality reliability of cold-rolled strip joints, avoiding the traditional destructive cupping test and microstructure analysis test, and ensuring the efficient operation of the cold-rolled strip production line.

[0118] Example 2

[0119] Step 1. This experiment uses a 2.5 mm thick Si 1.0 wt. % steel plate and uses a vibrating sample magnetometer (VSM) to measure its magnetic properties to obtain the hysteresis loop of the Si 1.0% wt steel plate. By calculation, its relative magnetic permeability is 8103.

[0120] Step 2, clarify the influence of detection frequency on signal characteristics. The detection frequency adjustment range of the eddy current detection host used in this experiment is 100-1MHz. An artificial defect with a depth of 2mm and a width of 0.3mm is designed on a steel plate sample with Si 1.0wt.%, and the excitation coil voltage frequency is 1kHz, 5kHz-50kHz (step 5kHz). Experiments are conducted on the designed defective samples, and the characteristic values ​​of each group of experimental data are averaged to obtain the optimal detection frequency of 5kHz.

[0121] Step 3, clarify the influence of coil voltage on signal characteristics, set the detection frequency to 5kHz, increase the voltage amplitude applied by the excitation coil from 1.2V to 12V (in steps of 1.2V), conduct experiments on the designed defective samples, extract impedance diagram features for 10 sets of data obtained from each set of parameter detection, average the characteristic values ​​of the 10 sets of data, and obtain the optimal excitation voltage of 9.6V.

[0122] Step 4, clarify the influence of the probe lift-off height on the signal characteristics, set the detection frequency to 5kHz, the excitation voltage to 9.6V, and the lift-off distance to 0.5-4mm (with a step of 0.5mm) to experiment on the designed defect pattern, calculate the average of the characteristic values ​​of each set of experimental data, and obtain the optimal lift-off distance of 1mm.

[0123] Step 5, clarify the effect of scanning speed on signal characteristics, set the detection frequency to 5kHz, the excitation voltage to 9.6V, the lift-off height to 1mm, and the robot display speed to 10%-100% (in steps of 10%), conduct experiments on the designed defect pattern, calculate the average of the characteristic values ​​of each set of experimental data, and select the optimal scanning speed of 100%.

[0124] Step 6. Clarify the effect of the scanning angle on the signal characteristics. Set the detection frequency to 5kHz, the excitation voltage to 9.6V, the lift-off height to 1mm, the robot display speed to 100%, and the probe reciprocating scanning angle to 0-90° (the angle step is 15°). Experiments are conducted on the designed defect pattern. The characteristic values ​​of each set of experimental data are averaged. It is found that except for the phase angle of 101.3° when the angle is 45°, the phase angles of the impedance diagram at other angles are all within the range of 80-90°. Considering the lift-off effect and the influence of the instrument's own interference, it can be considered that the phases of these impedance diagrams are basically equal. When the angle is less than 60°, the amplitude of the impedance diagram is around 0.2V, which is not easy to distinguish. This experiment selects an angle of 90°. See the eddy current detection scanning method and the process of forming the eddy current detection signal impedance diagram. Figure 6 When the probe scans directly above the defect along the positive X direction, the impedance diagram changes along the trajectory of the OMN, such as Figure 6 As shown in (a), when the probe continues to scan away from the defect in the positive X direction, the impedance diagram changes along the trajectory NLO, as shown in Figure 6 (b) is shown. The scanning mode of the probe is reciprocating scanning, as shown in Figure 6 (c). After reaching the maximum scanning position, scan in the negative X direction, and finally form Figure 6 (d) The “8” shaped impedance diagram shown.

[0125] Step 7, establish a welding joint characteristic defect feature organization database and verify its reliability.

[0126] Set the detection frequency to 5kHz, the excitation voltage to 9.6V, the lift-off height to 1mm, the robot display speed to 100%, the probe reciprocating scanning angle to 90°, and select multiple batches of welded joints for detection, and extract the defect-free impedance diagrams (see Figure 7 a) and defect impedance diagram (see Figure 7 b. Figure 7 c) characteristic parameters and the corresponding microstructure (see Figure 5 ), establish a database corresponding to the characteristic defects, characteristic structures and characteristic parameters of welded joints. Randomly select samples from different batches of products for eddy current testing and metallographic observation, and compare and verify them with the established database.

[0127] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When the use is implemented in whole or in part in the form of a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL) or wireless (e.g., infrared, wireless, microwave, etc.) mode) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk Solid State Disk (SSD)), etc.

[0128] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A cold-rolled steel strip weld joint reliability online detection method, characterized in that: The cold-rolled steel strip weld joint reliability online detection method comprises the following steps: Step 1: clarify the magnetic properties of the material to be tested; use a vibrating sample magnetometer (VSM) to measure the magnetic properties of the material to be tested, and obtain a hysteresis loop. Since the excitation magnetic field of eddy current testing is relatively low, the magnetic permeability is simplified to the average value of the slopes of two fitting straight lines, and the magnetic permeability of the material to be tested is obtained by calculation; a magnetic permeability less than or equal to 1 is a non-ferromagnetic material, and a magnetic permeability greater than 1 is a ferromagnetic material. The ferromagnetic material is magnetically saturated; Step 2: clarify the organizational characteristics of the welded joint to be inspected; after analyzing the cold cracking tendency of the steel strip by the cupping test, take a tensile specimen from the welded joint between the cracking point and the non-cracked point of the cupping test; after analyzing the mechanical properties of the characteristic area and the evolution characteristics of the organization during the deformation process, use metallographic observation to determine the organizational characteristics of the weld area of ​​the cold-rolled steel strip; Step 3: clarify the influence of the detection frequency on the impedance signal characteristics; the detection frequency adjustment range of the eddy current detection host used is 100-1MHz, the inspected material is a welded joint with different characteristic tissues, the excitation coil voltage frequency is 1kHz, 5kHz-50kHz, and the step is 5kHz; the welded joints with different characteristic tissues are inspected to obtain the frequency range in which the different characteristic tissues are most sensitive to the eddy current signal; Step 4: clarify the influence of coil voltage on signal characteristics; the excitation mode of the excitation coil is voltage excitation, with a maximum value of 12V, select the optimal detection frequency obtained in step 3, and detect the weld joint structure under different excitation coil voltages while keeping other parameters unchanged; extract the impedance map features for each set of experimental parameters, and calculate the average value of the feature values, and select a more reasonable excitation voltage from the average value; Step 5: clarify the influence of the probe lift-off height on the signal characteristics; the detection frequency is set to the optimal detection frequency measured in step 3, the excitation voltage is set to the excitation voltage obtained in step 4, the weld joint structure is tested at different lift-off distances in the range of 0.5 to 4 mm, the characteristic values ​​of each group of experimental data are averaged, and the optimal lift-off distance is selected; Step 6: clarify the influence of scanning speed on signal characteristics; set the detection frequency to the optimal detection frequency measured in step 3, set the excitation voltage to the excitation voltage obtained in step 4, set the lift-off height to the optimal lift-off distance obtained in step 5, test the weld joint structure at different scanning speeds, average the characteristic values ​​of each set of experimental data, and select the optimal scanning speed; Step 7: clarify the influence of scanning angle on signal characteristics; set the detection frequency to the optimal detection frequency measured in step 3, set the excitation voltage to the excitation voltage obtained in step 4, set the lift-off height to the optimal lift-off distance obtained in step 5, and the scanning speed to the optimal scanning speed obtained in step 6. Set the reciprocating scanning angle of the probe to 0-90°, and the angle step is 15°; detect the organizational characteristics of the welded joint, analyze the impedance characteristics, and eliminate the angle range with large errors. Step eight, establish a characteristic defect organization database for welding joints and conduct reliability verification.

2. The cold-rolled steel strip weld joint reliability online detection method according to claim 1, characterized in that: The step 8 of establishing a weld joint feature defect feature organization database includes: Taking the obtained parameters as the optimal parameters, multiple batches of welding joints were selected for testing, and the characteristic parameters of the measured defect-free impedance diagram and the defective impedance diagram were extracted respectively; welding joints with large differences in characteristic parameters were randomly selected for metallographic observation, and a database corresponding to the characteristic defects, characteristic organization and characteristic parameters of welding joints was established; samples were randomly selected from different batches of products for eddy current testing and metallographic observation, and compared and verified with the established database, and a database of the correlation between organization, performance and process parameters was established.

3. An online detection system for reliability of cold-rolled steel strip welded joints using the online detection method for reliability of cold-rolled steel strip welded joints as claimed in any one of claims 1 to 2, characterized in that: The cold-rolled steel strip welded joint reliability online detection system comprises: A material magnetic property determination module is used to determine the magnetic properties of the material to be tested; Joint structure feature determination module, used to clarify the structure features of the welded joint to be inspected; The signal characteristic influence determination module is used to respectively clarify the influence of the detection frequency on the impedance signal characteristics, the influence of the coil voltage on the signal characteristics, the influence of the probe lift-off height on the signal characteristics, the influence of the scanning speed on the signal characteristics, and the influence of the scanning angle on the signal characteristics; The feature organization database construction module is used to establish a feature organization database of welding joint feature defects and perform reliability verification.

4. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the online detection method for the reliability of cold-rolled steel strip welded joints as described in any one of claims 1 to 2.

5. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the online detection method for reliability of cold-rolled steel strip welded joints as claimed in any one of claims 1 to 2.

6. A cold-rolled silicon steel production line, characterized in that: The cold-rolled silicon steel production line is used to implement the steps of the online detection method for reliability of cold-rolled steel strip welded joints as described in any one of claims 1 to 2.

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