A method and device for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure

Abstract

The present application discloses a method and device for measuring the content and permeability of phase-transformed martensite magnetic structure, and relates to the technical field of magnetic structure content and permeability measurement. The method comprises: obtaining a phase-transformed martensite content standard sample curve; fitting the phase-transformed martensite content standard sample curve to obtain a relationship between the content of phase-transformed martensite microstructure and its relative permeability; constructing a theoretical mathematical model and a deconstrained formula; solving the theoretical mathematical model to obtain an optimal solution; substituting the optimal solution into the deconstrained formula to obtain the relative permeability and electrical conductivity of the measured pipe shaft; correcting the relative permeability to obtain a corrected relative permeability; substituting the corrected relative permeability into the relationship between the content of phase-transformed martensite microstructure and its relative permeability to obtain the content value of phase-transformed martensite microstructure of the measured pipe shaft. The present application can simultaneously measure the content of phase-transformed martensite structure and its permeability of austenitic stainless steel components online and non-destructively, and can improve the accuracy of measurement.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic structure content and magnetic permeability measurement, and in particular to a method and device for measuring the magnetic structure content and magnetic permeability of phase-transformed martensite. Background Art

[0002] 304 stainless steel is the most widely used steel in the production and manufacturing of industrial equipment. It has good corrosion resistance, heat resistance, low temperature strength and mechanical properties. The metallographic structure of 304 stainless steel is a non-magnetic austenite phase with a relative magnetic permeability of µr≈1.001. If austenitic stainless steel is deformed at room temperature (such as stretching and polishing, etc.), or simply the ambient temperature is reduced to far below room temperature, a large amount of ferromagnetic martensite phase will be formed and initially appear on the surface of the material, resulting in an increase in the material's magnetic permeability and a decrease in electrical conductivity. At the same time, the newly generated magnetic structure will seriously reduce the tensile strength of the raw material, resulting in reduced corrosion resistance and hydrogen embrittlement resistance, and finally causing macro defects such as stress corrosion and cracks. Some nuclear power austenitic stainless steel parts strictly require the material relative magnetic permeability µr≤1.300, and the turbine retaining ring forgings require µr≤1.051 to avoid excessive magnetic permeability causing heat. Therefore, it is necessary to regularly monitor the content of these magnetic microstructures and their magnetic permeability.

[0003] Traditional methods for determining the content of magnetic structures such as ferrite and martensite include lossy metallographic measurement and non-destructive magnetic measurement (including magnetic attraction and low-frequency electromagnetic induction), etc. However, it is not possible to simultaneously measure the magnetic structure content and magnetic permeability µr of the component material after the phase transformation. Lossy metallographic measurement methods are difficult to achieve online rapid detection and measurement. In addition, the low-frequency electromagnetic induction method is also affected by the curvature of the component and the electrical conductivity of the material, resulting in inaccurate measurement results. None of the above lossy methods can be applied to the real-time detection and long-term monitoring of in-service industrial equipment, and the detection efficiency is also low. Non-destructive magnetic measurement methods include permanent magnetic attraction and low-frequency electromagnetic induction. These two methods can only perform local point measurements and cannot perform large-area online imaging monitoring. Especially for curved workpieces (such as metal pipes and shaft cylindrical workpieces, etc.), the shaking of the probe seriously increases the measurement error. At the same time, the low-frequency electromagnetic induction method model is based on thick-walled flat components, and the measurement of thin-walled and large-curvature cylindrical components will bring unavoidable system errors.

[0004] Therefore, how to design a solution that can simultaneously measure magnetic tissue content and magnetic permeability and improve measurement accuracy has become a technical problem that urgently needs to be solved in this field. Summary of the invention

[0005] The purpose of this application is to provide a method and device for measuring the content of phase transformation martensite magnetic structure and magnetic permeability, which can simultaneously measure the content of phase transformation martensite structure and magnetic permeability value of austenitic stainless steel components online and non-destructively, and can improve the measurement accuracy.

[0006] To achieve the above objectives, this application provides the following solutions.

[0007] In a first aspect, the present application provides a method for measuring the content and magnetic permeability of a phase-transformed martensite magnetic structure. The method for measuring the content and magnetic permeability of a phase-transformed martensite magnetic structure comprises the following steps.

[0008] A phase transformation martensite content standard curve is obtained; the phase transformation martensite content standard curve is a curve made based on the phase transformation martensite content and relative magnetic permeability of the round rod sample.

[0009] The phase transformation martensite content standard sample curve is fitted to obtain a relationship between the phase transformation martensite microstructure content and its relative magnetic permeability.

[0010] Construct a theoretical mathematical model and a deconstraint formula; the theoretical mathematical model is a model constructed based on the measurement problem of the magnetic structure content and relative magnetic permeability of the measured pipe shaft; the deconstraint formula is a deconstraint processing of variables.

[0011] The theoretical mathematical model is solved to obtain an optimal solution.

[0012] Substituting the optimal solution into the deconstrained formula, the relative magnetic permeability and electrical conductivity of the measured pipe axis are obtained.

[0013] The relative magnetic permeability is corrected to obtain a corrected relative magnetic permeability.

[0014] The corrected relative magnetic permeability is substituted into the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability to obtain the phase transformation martensite microstructure content value of the measured pipe shaft.

[0015] In a second aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the above-described methods for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure.

[0016] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure.

[0017] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0018] The present application provides a method and device for measuring the content of phase-transformed martensite magnetic structure and magnetic permeability, the method comprising: obtaining a phase-transformed martensite content standard curve; the phase-transformed martensite content standard curve is a curve made based on the phase-transformed martensite content and relative magnetic permeability of a round rod sample; fitting the phase-transformed martensite content standard curve to obtain a relationship between the content of phase-transformed martensite microstructure and its relative magnetic permeability; constructing a theoretical mathematical model and a deconstrained formula; the theoretical mathematical model is a model constructed based on the measurement problem of the magnetic structure content and relative magnetic permeability of a measured pipe shaft; the deconstrained formula is a deconstrained processing of variables; solving the theoretical mathematical model to obtain an optimal solution; substituting the optimal solution into the deconstrained formula to obtain the relative magnetic permeability and electrical conductivity of the measured pipe shaft; correcting the relative magnetic permeability to obtain a corrected relative magnetic permeability; substituting the corrected relative magnetic permeability into the relationship between the content of phase-transformed martensite microstructure and its relative magnetic permeability to obtain the value of the content of phase-transformed martensite microstructure of the measured pipe shaft. The present application prepares a phase transformation martensite content standard curve, calculates the electromagnetic parameter inversion of the component, corrects the relative magnetic permeability, and substitutes the corrected relative magnetic permeability into the calibration relationship to obtain the phase transformation martensite microstructure content value. The present application can simultaneously measure the phase transformation martensite structure content and its magnetic permeability value of austenitic stainless steel components online and non-destructively, and can improve the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a diagram of the application environment of a method for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure in one embodiment of the present application.

[0021] Figure 2 A schematic flow chart of a method for measuring the magnetic structure content and magnetic permeability of phase-transformed martensite provided in one embodiment of the present application.

[0022] Figure 3 A detection schematic diagram provided for an embodiment of the present application.

[0023] Figure 4 A schematic diagram of the internal coil arrangement of an array probe provided in one embodiment of the present application.

[0024] Figure 5 A schematic diagram of a flexible foldable array probe provided in one embodiment of the present application.

[0025] Figure 6 A schematic diagram illustrating model size parameters provided in an embodiment of the present application.

[0026] Figure 7 A schematic diagram of the change in magnetic permeability and martensite content of a sample with deformation amount provided in one embodiment of the present application.

[0027] Figure 8 A schematic diagram of the change in conductivity of a sample with a change in deformation provided in an embodiment of the present application.

[0028] Fig. 9 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] This application derives an impedance increment expression for flexible eddy current array elements suitable for pipeline inspection based on the electromagnetic magnetic field analysis method, and establishes a fast method that can simultaneously measure the magnetic permeability, electrical conductivity and magnetic structure content such as ferrite of the material.

[0032] The method for measuring the content and permeability of the phase-transformed martensite magnetic structure provided in the embodiment of the present application can be applied to Figure 1In the application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store the data that the server 104 needs to process. The data storage system can be set up separately, integrated on the server 104, or placed on the cloud or other servers. The terminal 102 can send a phase transformation martensite content standard curve to the server 104, and the phase transformation martensite content standard curve is a curve made based on the phase transformation martensite content and relative magnetic permeability of the round rod sample; after the server 104 receives the phase transformation martensite content standard curve, for the phase transformation martensite content standard curve, the server 104 fits the phase transformation martensite content standard curve to obtain the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability; construct a theoretical mathematical model and a de-constraint formula; the theoretical mathematical model is based on the A model is constructed for measuring the magnetic structure content and relative magnetic permeability of a pipe shaft; the deconstrained formula is a deconstrained processing of variables; the theoretical mathematical model is solved to obtain an optimal solution; the optimal solution is substituted into the deconstrained formula to obtain the relative magnetic permeability and electrical conductivity of the measured pipe shaft; the relative magnetic permeability is corrected to obtain a corrected relative magnetic permeability; the corrected relative magnetic permeability is substituted into the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability to obtain the phase transformation martensite microstructure content value of the measured pipe shaft. The server 104 can feed back the obtained relative magnetic permeability and phase transformation martensite microstructure content value to the terminal 102. In addition, in some embodiments, the method for measuring the phase transformation martensite magnetic structure content and magnetic permeability can also be implemented independently by the server 104 or the terminal 102. For example, the terminal 102 can directly perform the phase transformation martensite magnetic structure content and magnetic permeability measurement on the phase transformation martensite content standard curve, or the server 104 can obtain the phase transformation martensite content standard curve from the data storage system and perform the phase transformation martensite magnetic structure content and magnetic permeability measurement on the phase transformation martensite content standard curve.

[0033] The terminal 102 may be, but is not limited to, various desktop computers, laptop computers, smart phones, and tablet computers. The server 104 may be implemented as an independent server or a server cluster consisting of multiple servers, or may be a cloud server.

[0034] In an exemplary embodiment, Figure 2 As shown, a method for measuring the content and permeability of phase-transformed martensite magnetic structure is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or by a terminal and a server together. In the embodiment of the present application, the method is applied to Figure 1 The server 104 in the example is used for explanation, and the steps include the following steps S1 to S7.

[0035] S1: Obtaining a phase transformation martensite content standard curve; the phase transformation martensite content standard curve is a curve made based on the phase transformation martensite content and relative magnetic permeability of a round rod sample.

[0036] S2: Fitting the phase transformation martensite content standard sample curve to obtain a relationship between the phase transformation martensite microstructure content and its relative magnetic permeability.

[0037] S3: Construct a theoretical mathematical model and a deconstraint formula; the theoretical mathematical model is a model constructed based on the measurement problem of the magnetic structure content and relative magnetic permeability of the measured pipe axis; the deconstraint formula is a deconstraint processing of variables.

[0038] S4: Solving the theoretical mathematical model to obtain an optimal solution.

[0039] S5: Substitute the optimal solution into the deconstrained formula to obtain the relative magnetic permeability and electrical conductivity of the measured pipe axis.

[0040] S6: Correcting the relative magnetic permeability to obtain a corrected relative magnetic permeability.

[0041] S7: Substituting the corrected relative magnetic permeability into the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability, to obtain the phase transformation martensite microstructure content value of the measured pipe shaft.

[0042] By implementing the above steps S1 to S7, the present application can simultaneously measure the content of phase transformation martensite structure and its magnetic permeability value of austenitic stainless steel components online and non-destructively, and can improve the accuracy of measurement.

[0043] like Figure 3 As shown, the FPCB coil can be formed into an array to detect the metal components of the tube shaft, and its probe form is as follows Figure 4 As shown. Since the probe (see Figure 5 ) is a thin ribbon structure that can fit closely to the curved surface of the tube shaft and reduce the effect of lift-off. The measurement problem of the magnetic structure content and magnetic permeability of the tube shaft can be constructed as the following inverse problem (i.e. theoretical mathematical model).

[0044] (1);

[0045] in, It is a theoretical mathematical model; is the unknown parameter vector, ; is the electrical conductivity of the component material; is the magnetic permeability of the component material; For the i The experimentally measured change in the imaginary part of the normalized coil impedance increment at a frequency; For the iFrequency; is the imaginary part of the normalized analytical expression for the impedance increment, , It means to evaluate the imaginary part of an expression. It can be calculated by formula (2).

[0046] (2);

[0047] in, is the coil impedance increment; It is the coil impedance value when the coil is tightly wrapped outside the pipe rod component; is the coil impedance when there is no conductor in the air, ; is the DC resistance of the coil when there is no conductor in the air; j is an imaginary unit; is the inductive reactance of the coil when there is no conductor in the air, ; ω is the angular frequency, , f is the eddy current detection frequency; is the inductance of the coil in air.

[0048] When considering the detection problem of a single FPCB coil, that is, Figure 6 For the detection model shown, the theoretical value of the coil impedance increment is calculated as follows.

[0049] (3);

[0050] in, N is the number of coil turns; ; The second type with absolute characteristic parameters of curvature m The value of the modified Bessel function of order, for The derivative of the modified Bessel function order and the ratio of the curvature radius of the curved coil ; d is the curvature radius of the thin circular spirally bent coil processed using FPCB technology, , b is the outer radius of the pipe or the radius of the round bar; is the radial distance from the bending coil to the outer surface of the tube shaft component; Sommerfeld integral , is the first-order modified Bessel function; is the reflection coefficient of the component to be measured; α is the integral variable of the impedance increment expression; is the outer radius of the coil, is the inner radius of the coil.

[0051] Select the reflection coefficient according to the pipe wall thickness to improve measurement efficiency:

[0052] 1) When the pipe wall thickness T > δ When , the object to be tested is a thick-walled tube and a solid round rod. is the penetration depth, is the magnetic permeability of the component. f calculate δ ; The first reflection coefficient should be selected from the following formula.

[0053] (4);

[0054] in, is the first reflection coefficient; The first type contains the absolute characteristic parameter of the outer diameter m The value of the modified Bessel function of order; is the propagation constant, ; is the order of Bessel function; is the magnetic permeability of the component material; is the reflection coefficient characteristic variable, ; b is the outer radius of the pipe or the radius of the round bar; is the integral variable ratio of the first modified Bessel function containing the characteristic parameter of the outer diameter; is the integral variable ratio of the first modified Bessel function containing the absolute characteristic parameter of the outer diameter, , for The derivative of The integration variable for the impedance increment expression; The second type contains the absolute characteristic parameter of the outer diameter m The value of the modified Bessel function of order; is the integral variable ratio of the second modified Bessel function with the absolute parameter of the outer diameter, , for The derivative of .

[0055] 2) When the pipe wall thickness T ≤ δ When the object to be measured is a thin-walled pipe, the second reflection coefficient should be selected from the following formula.

[0056] (5);

[0057] (6);

[0058] (7);

[0059] (8);

[0060] (9);

[0061] (10);

[0062] (11);

[0063] in, is the second reflection coefficient; The first type contains the absolute characteristic parameter of the outer diameter m The value of the modified Bessel function of order; The second type contains the absolute characteristic parameter of the outer diameter m The value of the modified Bessel function of order; is the coefficient parameter; is the magnetic permeability of the component material; The integration variable for the impedance increment expression; is the reflection coefficient characteristic variable; for V Reduced component 1; for V Reduced component 2; for U Reduced component 1; for U Reduced component 2; for Q Reduced component 1; for Q Reduced component 2; for T Reduced component 1; for T Reduced component 2; for S Reduced component 1; for S Reduced component 2; , , , , , , , , and The function is to simplify the writing of expressions; is the propagation constant; is the order of Bessel function; a is the inner radius of the pipe; b is the outer radius of the pipe or the radius of the round bar; The first type contains the characteristic parameter of outer diameter mThe value of the modified Bessel function of order; The second type contains the characteristic parameter of outer diameter m The value of the modified Bessel function of order; The second type contains the inner diameter characteristic parameter m The value of the modified Bessel function of order; The first type contains the characteristic parameter of inner diameter m The value of the modified Bessel function of order; The first type contains the absolute characteristic parameter of the inner diameter m The value of the modified Bessel function of order; for The derivative of for The derivative of for The derivative of for The derivative of for The derivative of .

[0064] Specifically, in step S4, the following steps are specifically included.

[0065] S41: Determine whether the pipe wall thickness of the measured pipe axis is greater than the penetration depth, and obtain a determination result.

[0066] S42: If the judgment result is yes, a first reflection coefficient is used to solve and obtain an optimal solution; the first reflection coefficient is a reflection coefficient of a thick-walled tube or a solid round rod, and is a coefficient obtained through the electromagnetic field boundary condition of a round rod eddy current detection model.

[0067] S43: If the judgment result is no, a second reflection coefficient is used to solve and obtain an optimal solution; the second reflection coefficient is a reflection coefficient of a thin-walled pipe, which is a coefficient obtained by an electromagnetic field boundary condition of a pipeline eddy current detection model.

[0068] The frequency sweep range can be selected as 100kHz-400kHz, and it is approximately assumed that the magnetic permeability of weak magnetic materials does not change with the detection frequency, and the phase transformation martensite is uniformly distributed on the surface of the specimen. For the nonlinear constrained optimization problem in equation (1), the Levenberg-Marquardt method is used to solve it, but the variables are unconstrained, so the variables are processed as follows.

[0069] (12);

[0070] This is the expression of the unconstrained form, where is the electrical conductivity of the component material; is the magnetic permeability of the component material; It is the upper limit or maximum value of the relative permeability change of the tested component after the martensitic phase transformation. It is generally obtained by taking samples of the same thickness and conducting material tensile tests. The maximum tensile amount should not exceed the deformation amount when the sample breaks. Figure 7 As shown, flat plate specimens and round bar specimens can be selected, and the maximum relative permeability measured by the spiral tube method when the tensile deformation does not exceed 30% can be taken. According to experience, Similarly, the two parameters corresponding to conductivity can also be obtained by the same method. Figure 8 get, =1.27 and =0.16 corresponds to the conductivity range of austenitic stainless steel components after microstructural phase transformation, which is generally smaller; the above parameter values , and They are all obtained based on experiments and experience and do not need to be accurate values. is the first initial value; is the second initial value; It is the first conductivity range of austenitic stainless steel components after microstructure phase transformation occurs; It is the second conductivity range of the austenitic stainless steel component after microstructure phase transformation; Integral for modified Bessel functions of the second kind; To reduce the amount; is the order of the Bessel function.

[0071] After the model formula is determined, the specific measurement steps are as follows.

[0072] Step 1: Preparation of phase transformation martensite content standard curve.

[0073] Processing and manufacturing round rod sample phase transformation martensite content CFM-relative magnetic permeability The calibration curve is fitted to obtain the characteristic function, that is, the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability is shown as follows.

[0074] (13);

[0075] in, is the relative magnetic permeability of the phase transformation martensite microstructure content; is the content of phase transformation martensite microstructure.

[0076] The calibration curve generally uses no less than four round bar specimens, which must contain the minimum and maximum phase transformation martensite content values ​​within the measurement range, and these values ​​are measured using standard methods.

[0077] Step 2: Inverse calculation of component electromagnetic parameters.

[0078] The theoretical mathematical model (1) and the unconstrained formula (12) are programmed and then the Levenberg-Marquardt program is called to solve them and the initial value is selected. and . After calculation, the optimal solution can be obtained ; In the Substituting into formula (12), the magnetic permeability and electrical conductivity of the measured pipe rod can be obtained as follows: and . As a reference value, its variation range is small and can be verified with the actual conductivity value at the measured location (such as using the four-probe method). The error between the measured value and the original value is large, so we can consider reselecting the initial value of the inversion ( , ) is calculated. Usually the inversion result is The relative permeability value obtained by magnetic measurement will be inconsistent. Make corrections.

[0079] Step 3: Correction of relative permeability.

[0080] The relative permeability correction curve generally uses at least four test blocks, which must contain the maximum and minimum relative permeability values ​​within the measurement range. The permeability measurement value can be obtained by the spiral tube method, using the maximum relative permeability obtained by direct magnetic measurement of the sample to correct the inverted maximum relative permeability, that is, the calculation formula for the corrected relative permeability is as follows.

[0081] (14);

[0082] in, is the relative magnetic permeability of the modified phase transformation martensite microstructure content; is the magnetic permeability obtained by inversion.

[0083] Step 4: Measurement of the transformation martensite microstructure content.

[0084] The relative magnetic permeability of the modified phase transformation martensite microstructure content obtained in step 3 is Substituting into the calibration equation (13) in step 1, the value of the phase transformation martensite microstructure content can be obtained, as shown in Table 1.

[0085] Table 1 Relative permeability and martensite content inversion values ​​of round bar samples

[0086]

[0087] It has been verified that the measurement error of the phase transformation martensite content and its magnetic permeability is less than 5% for components with deformation within 15% or maximum relative magnetic permeability change within 3, which meets the actual engineering measurement accuracy and is also applicable to the different requirements for phase transformation martensite content and relative magnetic permeability measurement in the standard specifications. Figure 4 The array probe shown can realize rapid measurement of a large area of ​​the component surface.

[0088] In summary, the present application has the following beneficial effects.

[0089] 1) The martensite content and magnetic permeability of austenitic stainless steel components can be measured online and non-destructively at the same time. Combined with a multiplexed array, imaging detection of both can be achieved.

[0090] 2) The influence of probe disturbance and component curvature on measurement is reduced. The flexible technology can be closely attached to the surface of the curved workpiece. The measurement mathematical model contains the component curvature radius parameter, which can reduce the error caused by the difference in curvature between the calibration sample and the measured workpiece.

[0091] 3) It has better measurement accuracy for thin-walled and large-curvature cylindrical components, because the wall thickness of such workpieces is generally smaller than the penetration depth. Other low-frequency measurement methods based on large wall thickness measurement models will bring large errors.

[0092] The present application also provides an application scenario, which applies the above-mentioned method for measuring the magnetic structure content and magnetic permeability of phase transformation martensite. Specifically: The method for measuring the magnetic structure content and magnetic permeability of phase transformation martensite provided in this embodiment can be applied in the magnetic structure content and magnetic permeability measurement scenario. The magnetic structure content and magnetic permeability measurement scenario includes: phase transformation martensite content standard curve acquisition link, fitting link, theoretical mathematical model and deconstraint formula construction link, solution link, first substitution link, correction link and second substitution link; obtaining the phase transformation martensite content standard curve; the phase transformation martensite content standard curve is a curve made based on the phase transformation martensite content and relative magnetic permeability of the round rod sample; fitting the phase transformation martensite content standard curve to obtain the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability; constructing a theoretical mathematical model and a deconstraint formula; the The theoretical mathematical model is a model constructed based on the measurement problem of the magnetic structure content and relative magnetic permeability of the measured pipe shaft; the deconstrained formula is a deconstrained processing of the variables; the theoretical mathematical model is solved to obtain the optimal solution; the optimal solution is substituted into the deconstrained formula to obtain the relative magnetic permeability and electrical conductivity of the measured pipe shaft; the relative magnetic permeability is corrected to obtain the corrected relative magnetic permeability; the corrected relative magnetic permeability is substituted into the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability to obtain the phase transformation martensite microstructure content value of the measured pipe shaft.

[0093] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Fig. 9 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store a standard curve of phase transformation martensite content. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for measuring the magnetic structure content and magnetic permeability of phase transformation martensite is implemented.

[0094] Those skilled in the art will understand that Fig. 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0095] In an exemplary embodiment, a computer device is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the above-mentioned method embodiments are implemented when the processor executes the computer program.

[0096] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the above-mentioned method embodiments are implemented.

[0097] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the above-mentioned method embodiments are implemented.

[0098] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0099] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0100] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0101] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure, characterized in that: The method for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure comprises: Obtaining a phase transformation martensite content standard curve; the phase transformation martensite content standard curve is a curve made based on the phase transformation martensite content and relative magnetic permeability of a round rod sample; Fitting the phase transformation martensite content standard sample curve to obtain a relationship between the phase transformation martensite microstructure content and its relative magnetic permeability; Constructing a theoretical mathematical model and a deconstraint formula; the theoretical mathematical model is a model constructed based on the measurement problem of the magnetic structure content and relative magnetic permeability of the measured pipe shaft; the deconstraint formula is a deconstraint processing of the variables; Solving the theoretical mathematical model to obtain an optimal solution; Substituting the optimal solution into the deconstrained formula, the relative magnetic permeability and electrical conductivity of the measured pipe axis are obtained; Correcting the relative magnetic permeability to obtain a corrected relative magnetic permeability; Substituting the corrected relative magnetic permeability into the relationship between the phase transformation martensite microstructure content and its relative magnetic permeability, to obtain the phase transformation martensite microstructure content value of the measured pipe shaft; The expression of the theoretical mathematical model is: ； in, It is a theoretical mathematical model; is the unknown parameter vector; For the i The experimentally measured change in the imaginary part of the normalized coil impedance increment at a frequency; The imaginary value of the normalized analytical expression for the impedance increment; , It means to find the imaginary part of the expression; ; is the coil impedance increment; It is the coil impedance value when the coil is tightly wrapped outside the pipe rod component; is the coil impedance when there is no conductor in the air, ; is the DC resistance of the coil when there is no conductor in the air; j is an imaginary unit; is the inductive reactance of the coil when there is no conductor in the air, ; ω is the angular frequency, , f is the eddy current detection frequency; is the inductance of the coil in air; For the i Frequency; is the electrical conductivity of the component material; is the magnetic permeability of the component material; Solving the theoretical mathematical model to obtain the optimal solution specifically includes: Determine whether the pipe wall thickness of the measured pipe axis is greater than the penetration depth, and obtain a determination result; If the judgment result is yes, the first reflection coefficient is used to solve and obtain the optimal solution; the first reflection coefficient is the reflection coefficient of the thick-walled tube or the solid round rod, which is the coefficient obtained by the electromagnetic field boundary condition of the round rod eddy current detection model; If the judgment result is no, the second reflection coefficient is used to solve and obtain the optimal solution; the second reflection coefficient is the reflection coefficient of the thin-walled pipe fitting, which is a coefficient obtained by the electromagnetic field boundary condition of the pipeline eddy current detection model.

2. The method for measuring the content and permeability of phase transformation martensite according to claim 1, characterized in that: The relationship between the phase transformation martensite microstructure content and its relative magnetic permeability is: ； in, is the relative magnetic permeability of the phase transformation martensite microstructure content; is the content of phase transformation martensite microstructure.

3. The method for measuring the content and permeability of phase transformation martensite according to claim 1, characterized in that: The expression of the deconstraint formula is: ； in, is the electrical conductivity of the component material; is the magnetic permeability of the component material; The upper limit or maximum value of the relative permeability change of the component to be tested after the martensitic phase transformation occurs; is the first initial value; is the second initial value; It is the first conductivity range of the austenitic stainless steel component after microstructural phase transformation occurs; It is the second conductivity range of austenitic stainless steel components after microstructure phase transformation occurs; Integral for modified Bessel functions of the second kind; To reduce the amount; is the order of the Bessel function.

4. The method for measuring the content and permeability of phase transformation martensite according to claim 1, characterized in that: The expression of the first reflection coefficient is: ； in, is the first reflection coefficient; The first type contains the absolute parameter of the outer diameter m The value of the modified Bessel function of order; is the propagation constant; is the order of Bessel function; is the magnetic permeability of the component material; is the reflection coefficient characteristic variable; b is the outer radius of the pipe or the radius of the round bar; is the integral variable ratio of the first kind modified Bessel function containing the outer diameter parameter; is the integral variable ratio of the first kind modified Bessel function containing the absolute parameter of the outer diameter; The integration variable for the impedance increment expression; The second type contains the absolute parameter of the outer diameter m The value of the modified Bessel function of order; is the integral variable ratio of the second kind modified Bessel function containing the absolute parameter of the outer diameter.

5. The method for measuring the content and permeability of phase transformation martensite according to claim 1, characterized in that: The expression of the second reflection coefficient is: ； ； ； ； ； ； ； in, is the second reflection coefficient; The first type contains the absolute parameter of the outer diameter m The value of the modified Bessel function of order; The second type contains the absolute parameter of the outer diameter m The value of the modified Bessel function of order; is the coefficient parameter; is the magnetic permeability of the component material; The integration variable for the impedance increment expression; is the reflection coefficient characteristic variable; for V Reduced component 1; for V Reduced component 2; for U Reduced component 1; for U Reduced component 2; for Q Reduced component 1; for Q Reduced component 2; for T Reduced component 1; for T Reduced component 2; for S Reduced component 1; for S Reduced component 2; , , , , , , , , and The function is to simplify the writing of expressions; is the propagation constant; is the order of Bessel function; a is the inner radius of the pipe; b is the outer radius of the pipe or the radius of the round bar; The first type contains the characteristic parameter of outer diameter m The value of the modified Bessel function of order; The second type contains the characteristic parameter of outer diameter m The value of the modified Bessel function of order; The second type contains the inner diameter characteristic parameter m The value of the modified Bessel function of order; The first type contains the characteristic parameter of inner diameter m The value of the modified Bessel function of order; The first type contains the absolute value of the inner diameter characteristic parameter m The value of the modified Bessel function of order; for The derivative of for The derivative of for The derivative of for The derivative of for The derivative of .

6. The method for measuring the content and permeability of phase transformation martensite according to claim 1, characterized in that: The calculation formula of the corrected relative magnetic permeability is: ； in, is the relative magnetic permeability of the modified phase transformation martensite microstructure content; is the magnetic permeability obtained by inversion.

7. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for measuring the content and magnetic permeability of phase-transformed martensite magnetic structure according to any one of claims 1 to 6 is implemented.

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