A non-destructive regulation method for welding stress based on acoustic / magnetic field

Abstract

The application discloses a welding stress nondestructive regulation and control method based on a sound / magnetic field, changes a tissue form and a stress state in a welding process through ultrasonic vibration energy, collects a metal magnetic memory signal of a welding joint to be regulated and controlled and fits to obtain an actual regulation and control slope, calculates a difference value between the actual regulation and control slope and a reference slope, obtains an ultrasonic amplitude and a fitting coefficient of the actual regulation and control, calculates a difference value between the fitting coefficient and a plurality of calibrated fitting coefficients, takes the ultrasonic amplitude corresponding to the calibrated fitting coefficient with the minimum error absolute value as a reference signal of the metal magnetic memory signal of the welding joint sample in a non-loaded state, and obtains a stress value from a difference value between the actual regulation and control slope and a reference signal slope; the application is related to ultrasonic signal energy attenuation induced by a weld tissue, a metal magnetic memory change gradient induced by welding stress and the like, realizes mapping and correlation among the ultrasonic amplitude, a metal magnetic memory signal characteristic parameter and stress, forms a closed-loop regulation and control, and has the advantages of rapidness, convenience, safety and on-line and the like.

Description

Technical Field

[0001] This invention belongs to the field of acoustic and magnetic signal application technology, specifically relating to a non-destructive control technology for welding stress that can be achieved quickly and without damage. Background Technology

[0002] Welding stress is a crucial factor influencing, and even determining, the service safety of welded structures. Therefore, exploring methods for evaluating residual welding stress is extremely important for ensuring the service safety and quality of welded structures and equipment. However, with increasing scarcity of resources and energy, simply evaluating the residual stress of welded joints cannot solve the current problem—that is, how to shift from stress evaluation to stress "control + evaluation." Based on this, achieving stress regulation (control + evaluation) is not only key to ensuring the service safety of welded structures but also an effective method to extend their service life and address energy resource waste.

[0003] Currently, the technical methods for controlling welding stress mainly focus on the following three aspects: ① optimization of welding processes; ② development of new welding equipment and methods; ③ development of new welding materials. While these methods have achieved some degree of control over welding stress, significant problems remain. One characteristic of the welding process—rapid cooling leading to directional solidification of the microstructure—is difficult to eliminate. Furthermore, these processes not only require numerous repeated experiments but are also susceptible to random factors during welding, making it difficult to achieve the desired control of welding stress. Therefore, how to control welding stress by altering the growth characteristics of the microstructure during welding has become a pressing issue in this field.

[0004] Welding stress evaluation techniques can be broadly categorized into non-destructive and destructive methods. Destructive methods, such as the pinhole method, evaluate stress by disrupting the overall performance of the welded structure or equipment. While effective, these methods have limitations: ① they cannot be applied rapidly and online; ② the results are based on small sample checks. Non-destructive methods, on the other hand, evaluate stress while maintaining the overall performance of the welded structure or equipment. Examples include magnetic, acoustic, optical, and radiographic methods. Comparatively, acoustic methods require high precision in terms of sample surface quality and shape; optical methods have extremely demanding environmental requirements; and radiographic methods are highly hazardous and require expensive equipment. These limitations primarily hinder their application in evaluating residual welding stress.

[0005] Metal magnetic memory technology, a type of magnetic method, boasts advantages such as high detection efficiency, convenient and safe operation, suitability for on-site testing, ease of mechanized testing, and online testing capabilities. Furthermore, the equipment is inexpensive and portable. Ultrasonic vibration, a type of power ultrasound, is a technique that alters certain states of a material's properties using ultrasonic energy. It offers advantages such as convenience, controllability, and ease of application. Therefore, combining ultrasonic vibration with metal magnetic memory stress evaluation technology can leverage the strengths of both. Based on this, the method disclosed in Chinese Patent Application Publication No. CN113667972A, entitled "A Method for Rapidly Controlling the Stress of Laser Cladding Layers Based on Acoustic / Magnetic Field," achieves non-destructive, rapid, and online control of laser cladding layer stress by integrating metal magnetic memory technology and ultrasonic impact technology. By changing ultrasonic impact parameters, laser cladding layer samples with different deformations are obtained. Combined with mechanical calibration experiments, metal magnetic memory signals of the laser cladding layer under different stress states are collected. A functional relationship between the slope of the metal magnetic memory signal and the stress of the laser cladding layer is established, and the relationship between the fitting coefficient and the ultrasonic impact coverage rate is obtained. Finally, the ultrasonic impact coverage rate is obtained. However, the problem with this method is that since the collected data is the magnetic memory signal of the laser cladding layer under various stress conditions, this magnetic memory signal is a weak magnetic signal. This weak magnetic signal is affected by many factors such as material, defect type, surface finish, external magnetic field and so on. It can only detect the approximate location and cannot detect qualitatively or quantitatively. Therefore, when this magnetic memory signal is used as a reference, it will inevitably affect the subsequent calculation results, resulting in low accuracy of the final control result. Summary of the Invention

[0006] This invention addresses the problems and shortcomings of current welding stress control techniques by proposing a non-destructive welding stress control method based on acoustic / magnetic fields. This method integrates ultrasonic vibration to alter the weld structure and control stress with metal magnetic memory evaluation of welding stress, forming a closed-loop stress control mechanism that ensures the accuracy of the metal magnetic memory evaluation results.

[0007] To achieve the above objectives, the technical solution adopted by the present invention, a non-destructive welding stress control method based on acoustic / magnetic field, is as follows:

[0008] Step 1): Sequentially collect the metal magnetic memory signals of the weld seams of multiple welded joint samples with different ultrasonic amplitudes, and fit the slope k′ of each metal magnetic memory signal of the weld seams of multiple welded joint samples with different ultrasonic amplitudes. The slope of the metal magnetic memory signal when no ultrasonic vibration is applied is set as the reference slope k0.

[0009] Step 2): Calculate the difference H′ between the slope k′ of each metal magnetic memory signal and the reference slope k0, and fit the relationship between the slope difference H′ and the ultrasonic amplitude.

[0010] Step 3): Prepare standard tensile specimens according to the static tensile standard for room temperature metallic materials. Apply progressive loading to the standard tensile specimens and collect the metal magnetic memory signal. Fit the slope k″′ of the metal magnetic memory signal of the standard tensile specimen under each loaded stress σ. Calculate the slope k″′ and the slope of the metal magnetic memory signal of the standard tensile specimen when unloaded. The slope is established by the difference H″′. The quantitative relationship between the difference H″′ and the stress σ is H″′=c″′·σ, where c″′ is the fitting coefficient of multiple calibrations of the standard tensile specimen at different ultrasonic amplitudes. A quantitative relationship is established between the fitting coefficient c″′ of multiple calibrations of the standard tensile specimen at different ultrasonic amplitudes and the corresponding ultrasonic amplitude:

[0011] Step 4): Using the same metal magnetic memory signal excitation and acquisition parameters as the welded joint sample, acquire the metal magnetic memory signal of the welded joint to be controlled and fit it to obtain the actual control slope k. 调 Calculate the actual control slope k 调 The difference H between the reference slope k0 and the aforementioned baseline slope k0 调 Based on the correspondence between the slope difference H′ and the ultrasonic amplitude described in step 2), the actual controlled ultrasonic amplitude Z is obtained. 调 Based on the quantitative relationship between the multiple calibrated fitting coefficients c″′ described in step 3) and the ultrasonic amplitude, the corresponding actual control fitting coefficient c is obtained. 调 ;

[0012] Step 5): Calculate the fitting coefficient c of the actual regulation. 调 The difference between the fitted coefficients c″′ and the ultrasonic amplitude corresponding to the fitted coefficient c″′ with the smallest absolute error, and the metal magnetic memory signal of the welded joint sample under unloaded conditions, is used as the reference signal to fit the slope of the reference signal.

[0013] Step 6): Calculate the actual control slope k. 调 With the slope of the reference signal The difference H is used to obtain the stress value based on the quantitative relationship between the slope difference H″′ and the stress σ described in step 3), thereby achieving non-destructive control of welding stress.

[0014] The advantages of this invention using the above technical solution are:

[0015] 1. This invention first changes the microstructure and stress state during the welding process by controlling the ultrasonic vibration energy, then evaluates the actual stress using metal magnetic memory technology, and finally provides a basis for subsequent stress control based on the actual stress of the welded joint after ultrasonic vibration.

[0016] The main innovations of this invention compared to the method provided in patent application publication number CN113667972A are as follows:

[0017] (1) The method provided in patent application publication number CN113667972A establishes the relationship between the slope of the metal magnetic memory signal and the stress; while the present invention establishes the correspondence between the difference in the slope of the metal magnetic memory signal and the ultrasonic amplitude.

[0018] (2) The method provided in patent application publication number CN113667972A establishes a relationship function between fitting coefficients and ultrasonic impact coverage, while this invention establishes a quantitative relationship between multiple fitting coefficients and ultrasonic amplitude.

[0019] (3) The method provided in patent application publication number CN113667972A is to calculate the required ultrasonic shock coverage based on the difference in slope of the metal magnetic memory signal, while the present invention calculates the stress value based on the difference between the slope of the metal magnetic memory signal and the slope of the selected reference signal.

[0020] Therefore, it can be seen that the present invention uses the attenuation of ultrasonic signal energy induced by weld structure and the gradient change of metal magnetic memory induced by welding stress as a correlation to realize the mapping correlation between ultrasonic amplitude, metal magnetic memory signal characteristic parameters and stress, forming a closed-loop control, which is different from the open-loop control method provided in patent application publication number CN113667972A. Therefore, it can overcome the problem of insufficient accuracy of metal magnetic memory signal.

[0021] 2. This invention prepares multiple sets of welded joint samples with different ultrasonic amplitudes and uses metal magnetic memory technology to calibrate the experiment. It then obtains the correlation between the fitting coefficient of the slope of the metal magnetic memory signal and the stress and the ultrasonic amplitude, ultimately realizing ultrasonic control of welding (weld) stress. This not only provides a non-destructive method for quantitative control of welding stress, but also provides a convenient and effective method for controlling welding stress. It has the advantages of being fast, convenient, safe, and online, and can reduce or even avoid service safety hazards of welded structures. Attached Figure Description

[0022] Figure 1 This is a graph showing the correspondence between the slope difference of the metal magnetic memory signal and the ultrasonic amplitude in an embodiment of the present invention.

[0023] Figure 2 This is a graph showing the relationship between the fitting coefficient of the magnetic memory signal of the welded joint sample and the ultrasonic amplitude in an embodiment of the present invention. Detailed Implementation

[0024] This invention proposes a non-destructive welding stress control method based on acoustic / magnetic fields. First, considering the properties of the welding material, the weld joint sample is a magnetic metal, and the welding method is fusion welding. Based on the welding technique, the welding process parameters of the weld joint are defined. The ultrasonic vibration waveform and the contact pattern between the ultrasonic vibrator and the welding plate are adjusted based on the welding direction to ensure good contact. The maximum ultrasonic amplitude is calculated based on the width of a single weld pass, ensuring that the maximum applied ultrasonic vibration value does not exceed 5% of the width of a single weld pass. At least three different ultrasonic amplitudes are applied to the welding plate.

[0025] By keeping the welding process parameters constant and sequentially changing the ultrasonic vibration amplitude, multiple welded joint samples without macroscopic defects were prepared with different ultrasonic amplitudes. In this invention, the acquisition method (parameters, direction, etc.) of the metal magnetic memory signal is the same.

[0026] The excitation parameters (energy) and lift-off height of the metal magnetic memory signal are fixed to ensure that the amplitude range of the metal magnetic memory signal of the welded joint is greater than the amplitude of the geomagnetic field. The moving direction and speed of the metal magnetic memory probe and the placement direction of the welded joint are fixed. This speed is matched with the parameters of the metal magnetic memory testing instrument to ensure continuous and uninterrupted display of the metal magnetic memory signal, and the acquisition parameters of the metal magnetic memory signal are kept constant.

[0027] The metal magnetic memory signals of the welds of multiple weld joint samples with different ultrasonic amplitudes z were sequentially collected from the weld center and in a direction parallel to the weld. The slope k′ of the metal magnetic memory signals of the welds of multiple weld joint samples with different ultrasonic amplitudes was obtained by fitting, as shown in the following formula (1):

[0028]

[0029] In the formula, k′ is the slope of the metal magnetic memory signal of the welded joint specimen (A / (m×mm)), Y max and Y min X represents the maximum and minimum amplitudes (A / m) of the metallic magnetic memory signal of the welded joint specimen, respectively. max and X min These represent the positions (mm) where the metal magnetic memory signal was acquired at the maximum and minimum amplitudes, respectively.

[0030] When no ultrasonic vibration is applied to the weld joint sample, i.e. the ultrasonic amplitude is 0%, the metal magnetic memory signal of the weld of multiple weld joint samples when the ultrasonic amplitude is 0% is collected, and the slope of the metal magnetic memory signal is obtained according to Equation (1), which is the reference slope k0.

[0031] Then calculate the difference H′ between the slope k′ of each metal magnetic memory signal and the reference slope k0, i.e. H′=k′-k0, establish the correspondence between the slope difference H′ of the metal magnetic memory signal and the ultrasonic amplitude z, and fit it using the following formula (2);

[0032] H′=a′-b′·c′ z (2)

[0033] In the formula: a′, b′, and c′ are fitting coefficients, H′ is the slope difference of the metal magnetic memory signal, and z is the ultrasonic amplitude.

[0034] Standard tensile specimens for welded joints were prepared according to the static tensile test standard for room temperature metallic materials. The width of the standard tensile specimen (gauge length) was no greater than 80% of the weld width, and the weld was the center of symmetry. The yield strength was measured, and the specimens were subjected to stress-relief annealing to ensure that the initial stress of the standard tensile specimens was no greater than ±10% of the yield strength. The highest loading load was designed based on the yield strength of the standard tensile specimens. The standard tensile specimens were loaded step by step, and the magnetic memory signal of the metal was collected. The slope of the magnetic memory signal of the standard tensile specimens under each stress (load) was calculated according to Equation (1). The slope of the magnetic memory signal of the standard tensile specimens when unloaded was defined as the reference slope. At least five sets of magnetic memory signals from standard tensile specimens under stress were sequentially collected to obtain different slopes k″′. The slopes k″′ of the magnetic memory signals from the standard tensile specimens and the reference slope were then calculated. The difference H″′, i.e. By fitting a linear function of equation (3), a quantitative relationship between the slope difference H″′ and the applied stress σ is established:

[0035] H″′=c″′·σ (3)

[0036] c″′ represents the fitting coefficients of multiple calibrations of the standard tensile specimen at different ultrasonic amplitudes z, and σ represents the stress (MPa).

[0037] Then, the following formula (4) was used to fit the results that conform to monotonic change, and a quantitative relationship was established between the multiple fitting coefficients c″′ of the standard tensile specimen at different ultrasonic amplitudes z and the corresponding ultrasonic amplitude z:

[0038] c″′=AB·C z (4)

[0039] In the formula: A, B, and C are fitting coefficients.

[0040] Finally, the same metal magnetic memory signal excitation (energy) parameters and acquisition parameters as the welded joint sample were selected, and the metal magnetic memory signal of the welded joint to be controlled was acquired. The slope k of the actual control was obtained by fitting it with equation (1).调 Then calculate the difference between it and the reference slope k0, i.e., H. 调 =k 调 Substituting -k0 into (2), we obtain its ultrasonic amplitude Z. 调 Subsequently, based on the ultrasonic amplitude Z... 调 According to equation (4), the corresponding fitting coefficient c of actual regulation is obtained. 调 .

[0041] Calculate the fitting coefficient c of the actual regulation 调 The difference between the fitting coefficients c″′ and multiple calibrated fitting coefficients is used to obtain the calibrated fitting coefficient c″′ with the smallest absolute error, and the corresponding ultrasonic amplitude is obtained. Therefore, the ultrasonic amplitude corresponding to the calibrated fitting coefficient with the smallest absolute error and the metal magnetic memory signal of the welded joint sample under unloaded conditions can be selected as the reference signal. Based on equation (1), the slope corresponding to this reference signal can be obtained.

[0042] Calculate the slope k of the metal magnetic memory signal of the weld joint to be controlled. 调 slope of the selected reference signal The difference H is used to replace H″′ in equation (3), and the stress value σ is calculated by substituting the difference H into equation (3). 调 This refers to the weld stress value of the weld joint to be adjusted, thereby achieving non-destructive control of welding stress.

[0043] The following is an embodiment of the present invention:

[0044] Example

[0045] Using Q235 steel as the base material and employing a laser-arc hybrid welding method with a plate thickness of 3mm, this embodiment is described using a butt joint of the same material as an example. The specific process is as follows:

[0046] Step 1: Select 3mm thick Q235 steel as the base material for welding. Choose a laser + arc hybrid welding method, without beveling, using a flat butt weld. Use a mixture of 82% argon and 18% carbon dioxide as the shielding gas. Adjust welding process parameters to ensure no macroscopic defects are generated inside the weld. Select a longitudinal wave ultrasonic vibration mode, with the propagation direction perpendicular to the welding direction. Place the ultrasonic vibrator horizontally, ensuring close contact with the side (thickness direction) of the Q235 steel. The width of a single weld pass is approximately 2.5mm. Calculate the ultrasonic amplitude z based on the principle that the maximum ultrasonic amplitude should not exceed 5% of the single weld pass width. Express the ultrasonic amplitude z as a percentage of the maximum amplitude. Prepare multiple weld joint samples with ultrasonic amplitude z values ​​of 0% (not applied), 10%, 50%, and 90% of the maximum amplitude, ensuring no macroscopic defects are generated inside the weld.

[0047] Step 2: Fix the excitation parameters of the metal magnetic memory signal. After calibration, the amplitude of the metal magnetic memory signal is within the range of the Earth's magnetic field. Fix the lifting height of the metal magnetic memory probe to 1.0 mm (distance from the weld measurement position). Fix the welded joint horizontally, and move the metal magnetic memory probe parallel to the weld at a speed of 2.5 m / min. Collect the metal magnetic memory signal of the weld when the ultrasonic amplitude z is 0%, 10%, 50%, and 90% in the direction parallel to the weld. Fit the results with the linear function of Equation (1) to obtain the slope k′ of the metal magnetic memory signal of the welded joint sample with different ultrasonic amplitude z as 39.82, 50.16, 62.18, and 70.85, respectively, in A / (m×mm). Among them, the slope k′=39.82 is the slope of the metal magnetic memory signal when no ultrasonic vibration is applied, that is, when the ultrasonic amplitude z is 0%. With k′=39.82 as the reference slope k0, k′=k0.

[0048] Step 3: Calculate the difference H′ between the slope of the sample metal magnetic memory signal and the reference slope k0 when the ultrasonic amplitude is 10%, 50%, and 90%, respectively. The differences H′ are 10.34, 22.36, and 31.03, respectively. Then, establish the correspondence between this slope difference H′ and the ultrasonic amplitude z, as follows: Figure 1 As shown, and fitted using equation (2), the quantitative relationship is shown in equation (5):

[0049] H′=34.22-32.95·0.096 z (5)

[0050] In the formula: H′ is the slope difference, z is the ultrasonic amplitude, and the fitting coefficients a′, b′ and c′ in formula (2) are 34.22, 32.95 and 0.096, respectively.

[0051] Step four: According to GB / T2002-228 Metallic Materials - Tensile Testing at Room Temperature, process standard tensile specimens for welded joints with a thickness of 3.0 mm and a weld width of 2.8 mm. Vacuum stress-relief annealing is then performed (with parameters: vacuum degree of 10...). -1Pa, the maximum heating temperature is 860℃, the holding time is 30min, and the sample is taken out after furnace cooling to 200℃) The standard tensile specimens of the welded joint were subjected to stress-relief annealing treatment to obtain specimens with initial stress less than 30MPa, and their yield strengths were measured respectively, which were 308MPa, 326MPa, 381MPa and 335MPa. The yield strength was defined as the maximum loading stress. The standard tensile specimens were loaded stepwise at a rate of 0.5kN / s. After reaching the predetermined stress, the load was held for 120s and the metal magnetic memory signal of the weld center at 0MPa, 50MPa, 100MPa, 150MPa, 200MPa, 280MPa and the maximum loading stress were collected respectively. The slope of the metal magnetic memory signal of the specimen at 0MPa, 50MPa, 100MPa, 150MPa, 200MPa, 280MPa and the maximum loading stress was obtained by fitting it with the linear function of Equation (1), which were 0.0001, 0.00011, 0.00012 and 0.00013A / (m×mm). The slope of the metal magnetic memory signal of the specimen at 0MPa without loading was defined as the reference slope. Calculate the slope of the metal magnetic memory signal and the reference slope for each stress. The difference H″′ (absolute value) is obtained, and the correspondence between the slope difference H″′ and the stress σ is established. Equation (2) is used to fit it, and finally the quantitative relationship between the slope difference of the metal magnetic memory signal and the stress is obtained, as shown in Equation (6).

[0052]

[0053] In the formula: H″′0, H″′ 0.1 H″′ 0.5 H″′ 0.9 The slope difference (A / m / mm) of the metal magnetic memory signal of the standard tensile specimen at different ultrasonic amplitudes (0%, 10%, 50% and 90%) is given by σ, where σ is the stress (MPa). At this time, the fitting coefficients c″′ of the multiple calibrations are 0.14472, 0.17161, 0.20988 and 0.21575, respectively.

[0054] Step 5: Establish the correspondence between the multiple calibrated fitting coefficients c″′ from Step 4 and the ultrasonic amplitude z, see... Figure 2 As shown, the results of ultrasound amplitude z being 0%, 10%, 50% and 90% are fitted using equation (4), and the quantitative expression of the fitting coefficient and ultrasound amplitude is obtained, as shown in equation (7) below:

[0055] c″′=0.2168-0.07213·0.00938 z (7)

[0056] Step 6: Select the same metal magnetic memory signal excitation (energy) parameters and acquisition parameters as in Step 2, acquire the metal magnetic memory signal of the weld joint to be controlled along the center of the weld, and use the linear function in Equation (1) to fit it to obtain the slope k that is actually controlled. 调 =52.063, then calculate the difference H between it and the baseline slope k′ = 39.82A / (m×mm) defined in step two. 调 =52.063-39.82=12.243, substituting into the quantitative relationship (5) in step three, the ultrasonic amplitude Z is calculated. 调 The equivalent value is 0.176, and then the ultrasonic amplitude Z is... 调 Substituting the fitting coefficients into the quantitative expression (7) for the ultrasonic amplitude in step five, we obtain the corresponding fitting coefficients c. 调 =0.185.

[0057] Step 7: Calculate the fitting coefficient c 调 The difference between the fitted coefficients c″′ = 0.185 and the values ​​c″′ = 0.14472, 0.17161, 0.20988, and 0.21575 calibrated in step four is used to obtain the fitted coefficient c. 调 The minimum absolute value of the error of the multiple calibration fitting coefficients c″′ is 0.01339 = 0.185 - 0.17161, which is closest to the calibration fitting coefficient of the welded joint sample when the ultrasonic amplitude is 10%. Therefore, the metal magnetic memory signal under no load when the ultrasonic amplitude is 10% is selected as the reference signal. Based on equation (1), the slope corresponding to the reference signal can be obtained.

[0058] Step 8: Calculate the slope k of the metal magnetic memory signal of the controlled weld joint. 调 The slope of the reference signal of the weld joint calibration specimen selected in step seven. The difference H is approximately 52.06289. Substituting this difference H into the formula for ultrasonic amplitude of 10% in equation (6), the stress value is calculated, i.e., substituting into equation H″′ 0.1 The stress value is calculated by σ = 0.17161, which is the weld stress value of the welded joint, approximately 303 MPa. This achieves non-destructive control of welding stress.

Claims

1. A non-destructive method for controlling welding stress based on acoustic / magnetic fields, characterized in that: Includes the following steps: Step 1): Sequentially collect the metal magnetic memory signals of the weld seams of multiple welded joint samples with different ultrasonic amplitudes, and fit the slope k′ of each metal magnetic memory signal of the weld seams of multiple welded joint samples with different ultrasonic amplitudes. The slope of the metal magnetic memory signal when no ultrasonic vibration is applied is set as the reference slope k0. Step 2): Calculate the difference H′ between the slope k′ of each metal magnetic memory signal and the reference slope k0, and fit the relationship between the slope difference H′ and the ultrasonic amplitude. Step 3): Prepare standard tensile specimens according to the static tensile standard for room temperature metallic materials. Apply progressive loading to the standard tensile specimens and collect the metal magnetic memory signal. Fit the slope k″′ of the metal magnetic memory signal of the standard tensile specimen under each loaded stress σ. Calculate the slope k″′ and the slope of the metal magnetic memory signal of the standard tensile specimen when unloaded. The difference H″′ is used to establish a quantitative relationship between the difference H″′ and the stress σ as H″′=c″′·σ, where c″′ is the fitting coefficient of multiple calibrations of the standard tensile specimen at different ultrasonic amplitudes. A quantitative relationship is then established between the fitting coefficient c″′ of multiple calibrations of the standard tensile specimen at different ultrasonic amplitudes and the corresponding ultrasonic amplitude. Step 4): Using the same metal magnetic memory signal excitation and acquisition parameters as the welded joint sample, acquire the metal magnetic memory signal of the welded joint to be controlled and fit it to obtain the actual control slope k. 调 Calculate the actual control slope k 调 The difference H between the reference slope k0 and the aforementioned baseline slope k0 调 Based on the correspondence between the slope difference H′ and the ultrasonic amplitude described in step 2), the actual controlled ultrasonic amplitude Z is obtained. 调 Based on the quantitative relationship between the multiple calibrated fitting coefficients c″′ described in step 3) and the ultrasonic amplitude, the corresponding actual control fitting coefficient c is obtained. 调 ; Step 5): Calculate the fitting coefficient c of the actual regulation. 调 The difference between the multiple calibrated fitting coefficients c″′ and the ultrasonic amplitude corresponding to the calibrated fitting coefficient c″′ with the smallest absolute error, and the metal magnetic memory signal of the welded joint sample under unloaded conditions, is used as the reference signal to fit the slope of the reference signal. Step 6): Calculate the actual control slope k. 调 With the slope of the reference signal The difference H is used to obtain the stress value based on the quantitative relationship between the slope difference H″′ and the stress σ described in step 3), thereby achieving non-destructive control of welding stress.

2. The non-destructive welding stress control method based on acoustic / magnetic field according to claim 1, characterized in that: In step 1): the applied ultrasonic amplitude is 0%, 10%, 50%, and 90% of the maximum ultrasonic amplitude.

3. The non-destructive welding stress control method based on acoustic / magnetic field according to claim 1, characterized in that: In step 1), the slope of each metal magnetic memory signal Y max and Y min X represents the maximum and minimum amplitudes of the metallic magnetic memory signal of the welded joint specimen, respectively. max and X min These are the locations where the metal magnetic memory signal was acquired at the maximum and minimum amplitudes, respectively.

4. The non-destructive welding stress control method based on acoustic / magnetic field according to claim 1, characterized in that: In step 2), the relationship between the slope difference H′ and the ultrasonic amplitude is H′=a′-b′·c′. z , where a′, b′, and c′ are fitting coefficients, and z is the ultrasonic amplitude.

5. The non-destructive welding stress control method based on acoustic / magnetic field according to claim 1, characterized in that: In step 3), the quantitative relationship between the multiple calibrated fitting coefficients c″′ and the ultrasonic amplitude is c″′=AB·C z A, B, and C are fitting coefficients, and z is the ultrasonic amplitude.

6. A non-destructive welding stress control method based on acoustic / magnetic field according to any one of claims 1-5, characterized in that: The width of the standard tensile specimen shall not exceed 80% of the weld width, and the weld shall be the center of symmetry. The initial stress when loading the standard tensile specimen in stages shall not exceed ±10% of the specimen's yield strength.

7. A non-destructive welding stress control method based on acoustic / magnetic field according to any one of claims 1-5, characterized in that: The magnetic memory signals of metals from at least five sets of standard tensile specimens under stress were collected sequentially to obtain different slopes k″′.

8. The non-destructive welding stress control method based on acoustic / magnetic field according to claim 2, characterized in that: The maximum ultrasonic amplitude is calculated based on the width of a single weld pass, and the maximum ultrasonic amplitude applied shall not exceed 5% of the width of a single weld pass.

9. The non-destructive welding stress control method based on acoustic / magnetic field according to claim 8, characterized in that: No fewer than three different ultrasonic amplitudes were applied.

10. A non-destructive welding stress control method based on acoustic / magnetic field according to any one of claims 1-5, characterized in that: The metal magnetic memory signals of the welds of multiple weld joint samples with different ultrasonic amplitudes were sequentially collected along the center of the weld and parallel to the weld direction. The acquisition methods of the metal magnetic memory signals were all the same.

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