Method and system for evaluating creep failure of welded joint in lead-bismuth environment

Abstract

The invention belongs to the technical field of creep failure, and relates to a method and a system for evaluating creep failure of a welding joint in a lead-bismuth environment. The method comprises the steps that creep life data are obtained by testing a welded joint creep sample in a lead-bismuth environment, a stress-fracture life design curve is obtained, a creep fracture factor is calculated, and the creep performance difference between a welded joint and a base material is quantified; a creep constitutive model is established in combination with test data, and a reliable basis is provided for numerical analysis; a numerical model is established on the basis of actual geometric parameters, a creep fracture factor is coupled, a creep damage model is established by using a ductility depletion theory and a Cocks-Ashby model, and the factor reliability is verified by comparing calculation and test results, so that the scientificity and accuracy of the evaluation method are ensured. The invention provides a systematic and accurate technical path for evaluating the creep failure of the welding joint in the lead-bismuth environment, and has important guiding significance for safety evaluation of a welding structure in related engineering application.

Description

Technical Field

[0001] This invention belongs to the field of creep failure technology, and relates to a method and system for assessing creep failure of welded joints in a lead-bismuth environment. Background Technology

[0002] Nuclear power has developed rapidly due to its significant economic, social, and environmental advantages, and lead-bismuth fast-cooling reactors are among the most advanced fourth-generation nuclear energy systems. Nuclear power components operate for extended periods in complex environments involving high temperatures, radiation, and loads; failure can have catastrophic consequences. Welded joints operate in even more complex environments with high residual stress, making failure assessment often difficult. Case studies of numerous nuclear power plant accidents have revealed that the primary failure modes of welded joints in nuclear power components are excessive deformation and fracture, with creep failure being a major contributing factor to nuclear power system failures. Currently, there are no established methods for assessing high-temperature creep failure of welded joints in lead-bismuth environments. To ensure the long-term safe and reliable operation of nuclear power components and to provide a theoretical basis for the design and construction of nuclear power systems, a precise and simple method is urgently needed to assess creep failure of welded joints in lead-bismuth environments. Summary of the Invention

[0003] The purpose of this invention is to solve the problem that there is no relevant way to assess the high-temperature creep failure of welded joints in lead-bismuth environments in the prior art, and to provide a method and system for assessing the creep failure of welded joints in lead-bismuth environments.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for assessing creep failure of welded joints in a lead-bismuth environment, comprising:

[0006] Creep specimens of welded joints were tested in a lead-bismuth environment to obtain creep life data under different stress levels, and creep stress-fracture life design curves in the lead-bismuth environment were obtained respectively; the welded joint includes base metal, heat-affected zone and weld metal;

[0007] The creep fracture factor of the welded joint in the lead-bismuth environment is obtained by comparing the average creep stress at the same creep fracture life in the creep life design curve of the base material with the creep life design curve of the welded joint in the lead-bismuth environment.

[0008] A creep constitutive model was established based on creep test data of lead-bismuth environment of base material and weld metal;

[0009] A numerical model of the creep specimen of the welded joint was established based on the geometric parameters of the creep specimen of the welded joint under lead-bismuth environment.

[0010] The creep fracture factor is coupled into the creep constitutive model, and the creep fracture life of the base material and the weld joint under lead-bismuth environment is obtained using the numerical model of the weld joint creep specimen. This verifies the reliability of the creep fracture factor of the weld joint under lead-bismuth environment. If the fatigue failure factor is deemed reliable, the creep failure factor of the weld joint under lead-bismuth environment is determined.

[0011] A further improvement of the present invention is that:

[0012] Furthermore, creep specimens of the welded joints were tested in a lead-bismuth environment to obtain creep life data under different stress levels. Creep stress-fracture life design curves for the lead-bismuth environment were then obtained, as follows:

[0013] High-temperature creep fracture test was carried out on creep specimens of the base material of the welded joint under lead-bismuth environment to obtain creep strain-time curves under different stresses; the creep life under various stress levels was integrated to obtain the creep stress-fracture life design curve of the base material.

[0014] Creep specimens were processed from the weld seam of the welded joint, and high-temperature creep fracture tests were carried out on the deposited metal under different stress conditions in a lead-bismuth environment to obtain the creep strain-time curves of the weld seam under different stress levels in a lead-bismuth environment.

[0015] High-temperature creep endurance tests with different stress controls were conducted on the creep specimens of the welded joints in a lead-bismuth environment; the creep stress-fracture life design curve of the welded joints in the lead-bismuth environment was obtained by the same processing method as that used to obtain the creep stress-fracture life design curve of the base material.

[0016] Furthermore, the creep life design curve of the welded joint in the lead-bismuth environment is compared with the creep life design curve of the base material at the same creep fracture life to obtain the creep fracture factor of the welded joint in the lead-bismuth environment, specifically:

[0017]

[0018] Among them, C cr The creep rupture factor of the welded joint in a lead-bismuth environment. The creep life design curve is based on the corresponding creep fracture life. The obtained creep stress of the base material, The creep life design curve of the welded joint is based on the corresponding creep fracture life. The creep stress of the welded joint was obtained.

[0019] Furthermore, based on creep test data of lead-bismuth environment in the base material and weld metal, a creep constitutive model is established, specifically as follows:

[0020] Based on creep test data of lead-bismuth in the base material and weld metal, we analyzed the creep strain-time curves under different stress levels, extracted creep parameters, and established a creep deformation model.

[0021] The creep deformation model is as follows:

[0022]

[0023] in, The creep strain rate represents the steady-state stage, / h; σ is the applied stress level, MPa; B is the creep strain coefficient; n is the creep strain exponent.

[0024] Furthermore, based on the geometric parameters of the welded joint creep specimens in a lead-bismuth environment, a numerical model of the welded joint creep specimens is established, specifically as follows:

[0025] Based on the gauge length, heat-affected zone width, groove type, and groove size of the actual welded joint creep specimen, the material properties are set as base metal, heat-affected zone, and weld in the corresponding region of the numerical model of the welded joint creep specimen. The obtained creep constitutive model parameters are applied to the base metal and weld to establish the numerical model of the welded joint creep specimen.

[0026] Furthermore, the creep fracture factor is coupled to the creep constitutive model to verify the reliability of the creep fracture factor of the welded joint in the lead-bismuth environment, specifically:

[0027] Creep fracture factor C cr A creep constitutive model of the heat-affected zone (HAZ) is obtained by coupling the model to the creep constitutive model of the base material and applied to the HAZ region of the numerical model of the weld joint. A creep damage model is established based on the ductility depletion theory. Creep failure is considered to occur when the damage value ω reaches 0.99. The creep fracture life of the base material and the weld joint under lead-bismuth conditions is calculated using the numerical model of the weld joint creep specimen. The creep life design curves of the base material and the weld joint under lead-bismuth conditions are compared with those to verify the reliability of the calculated creep fracture factor of the weld joint under lead-bismuth conditions.

[0028] The coupled creep deformation model is as follows:

[0029]

[0030] The theory of ductility depletion includes:

[0031]

[0032] in, For creep damage rate, and These represent creep strain rate and multiaxial creep fracture strain, respectively. The relationship between the stress state of the current infinitesimal element and the uniaxial fracture strain is related to the stress state and the uniaxial fracture strain. The Cocks-Ashby model is used to describe this relationship:

[0033]

[0034] Where, σ m It is hydrostatic pressure, σ e It is the equivalent stress, σ m / σ e It is stress triaxiality, ε f It is uniaxial fracture strain;

[0035] The damage value ω at any given time can be obtained by integrating over time using formula (4):

[0036]

[0037] If the calculated creep rupture life of the base material and weld joint under corresponding conditions in a lead-bismuth environment matches the creep life design curve of the base material and weld joint in a lead-bismuth environment, then the calculated creep rupture factor C of the weld joint in a lead-bismuth environment is considered to be... cr reliable.

[0038] A creep failure assessment system for welded joints in a lead-bismuth environment includes:

[0039] The acquisition module tests the creep specimens of the welded joint in a lead-bismuth environment to obtain creep life data under different stress levels, and obtains the creep stress-fracture life design curves in the lead-bismuth environment; the welded joint includes the base material, the heat-affected zone and the weld metal.

[0040] The comparison module compares the creep life design curve of the welded joint in the lead-bismuth environment with the average creep stress at the same creep fracture life in the creep life design curve of the base material to obtain the creep fracture factor of the welded joint in the lead-bismuth environment.

[0041] The first establishment module establishes a creep constitutive model based on creep test data of lead-bismuth environment of base material and weld metal.

[0042] The second establishment module establishes a numerical model of the welded joint creep specimen based on the geometric parameters of the welded joint creep specimen under lead-bismuth environment.

[0043] The verification module couples the creep fracture factor into the creep constitutive model and uses the numerical model of the welded joint creep specimen to obtain the creep fracture life of the base material and the welded joint under lead-bismuth conditions, thereby verifying the reliability of the creep fracture factor of the welded joint under lead-bismuth conditions; if the fatigue failure factor is deemed reliable, the creep failure factor of the welded joint under lead-bismuth conditions is determined.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This invention obtains creep life data from creep tests of welded joint specimens in a lead-bismuth environment, acquires stress-fracture life design curves, and calculates the creep fracture factor to quantify the difference in creep performance between the welded joint and the base material. A creep constitutive model is established based on the experimental data, providing a reliable basis for numerical analysis. A numerical model is built based on actual geometric parameters and coupled with the creep fracture factor. A creep damage model is constructed using ductility exhaustion theory and the Cocks-Ashby model. The reliability of the factor is verified by comparing the calculated and experimental results, ensuring the scientific validity and accuracy of the evaluation method. This invention provides a systematic and precise technical approach for assessing creep failure of welded joints in a lead-bismuth environment, and has significant guiding significance for the safety assessment of welded structures in related engineering applications. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic flowchart of the creep failure assessment method for welded joints in a lead-bismuth environment according to the present invention.

[0048] Figure 2 This is a schematic diagram of the structure of the lead-bismuth environment welded joint creep failure assessment system of the present invention;

[0049] Figure 3 This is a schematic diagram of the creep strain-time relationship curves of the base material under different stresses;

[0050] Figure 4 A schematic diagram for calculating the creep fracture factor of welded joints in a lead-bismuth environment;

[0051] Figure 5 A comparison chart of creep test values ​​and calculated values ​​of the base material in a lead-bismuth environment;

[0052] Figure 6 This is a schematic diagram illustrating the application of the creep fracture factor. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0055] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0056] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0057] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0058] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0059] The present invention will now be described in further detail with reference to the accompanying drawings:

[0060] See Figure 1 This invention discloses a method for assessing creep failure of welded joints in a lead-bismuth environment, comprising:

[0061] S101: The creep specimens of the welded joint are tested in a lead-bismuth environment to obtain creep life data under different stress levels, and the creep stress-fracture life design curves in the lead-bismuth environment are obtained respectively; the welded joint includes the base material, the heat-affected zone and the weld metal.

[0062] High-temperature creep fracture test was carried out on creep specimens of the base material of the welded joint under lead-bismuth environment to obtain creep strain-time curves under different stresses; the creep life under various stress levels was integrated to obtain the creep stress-fracture life design curve of the base material.

[0063] Creep specimens were processed from the weld seam of the welded joint, and high-temperature creep fracture tests were carried out on the deposited metal under different stress conditions in a lead-bismuth environment to obtain the creep stress-fracture life design curve of the weld seam in a lead-bismuth environment.

[0064] High-temperature creep endurance tests with different stress controls were conducted on the creep specimens of the welded joints in a lead-bismuth environment; the creep stress-fracture life design curve of the welded joints in the lead-bismuth environment was obtained by the same processing method as that used to obtain the creep stress-fracture life design curve of the base material.

[0065] S102: The creep fracture factor of the welded joint under lead-bismuth environment is obtained by comparing the average creep stress at the same creep fracture life in the creep life design curve of the welded joint under lead-bismuth environment with the creep fracture life design curve of the base material.

[0066]

[0067] Among them, C cr The creep rupture factor of the welded joint in a lead-bismuth environment. The creep life design curve is based on the corresponding creep fracture life. The obtained creep stress of the base material, The creep life design curve of the welded joint is based on the corresponding creep fracture life. The creep stress of the welded joint was obtained.

[0068] S103: Based on creep test data of lead-bismuth environment of base material and weld metal, establish a creep constitutive model;

[0069] Based on creep test data of lead-bismuth in the base material and weld metal, we analyzed the creep strain-time curves under different stress levels, extracted creep parameters, and established a creep deformation model.

[0070] The creep deformation model is as follows:

[0071]

[0072] S104: Based on the geometric parameters of the welded joint creep specimens under lead-bismuth conditions, a numerical model of the welded joint creep specimens is established, specifically as follows:

[0073] Based on the gauge length, heat-affected zone width, groove type, and groove size of the actual welded joint creep specimen, the material properties are set as base metal, heat-affected zone, and weld in the corresponding region of the numerical model of the welded joint creep specimen. The obtained creep constitutive model parameters are applied to the base metal and weld to establish the numerical model of the welded joint creep specimen.

[0074] S105: Couple the creep fracture factor into the creep constitutive model, and use the numerical model of the creep specimen of the welded joint to obtain the creep fracture life of the base material and the welded joint in the lead-bismuth environment, thereby verifying the reliability of the creep fracture factor of the welded joint in the lead-bismuth environment; if the fatigue failure factor is deemed reliable, then determine the creep failure factor of the welded joint in the lead-bismuth environment.

[0075] Creep fracture factor C cr A creep constitutive model of the heat-affected zone (HAZ) is obtained by coupling the model to the creep constitutive model of the base material and applied to the HAZ region of the numerical model of the weld joint. A creep damage model is established based on the ductility depletion theory. Creep failure is considered to occur when the damage value ω reaches 0.99. The creep fracture life of the base material and the weld joint under lead-bismuth conditions is calculated using the numerical model of the weld joint creep specimen. The creep life design curves of the base material and the weld joint under lead-bismuth conditions are compared with those to verify the reliability of the calculated creep fracture factor of the weld joint under lead-bismuth conditions.

[0076] The coupled creep deformation model is as follows:

[0077]

[0078] The theory of ductility depletion includes:

[0079]

[0080] in, For creep damage rate, and These represent creep strain rate and multiaxial creep fracture strain, respectively. The stress state and uniaxial fracture strain of the current infinitesimal element are related to this relationship, which is described using the Cocks-Ashby model:

[0081]

[0082] Where, σ m It is hydrostatic pressure, σe It is the equivalent stress, σ m / σ e It is stress triaxiality, ε f It is uniaxial fracture strain;

[0083] The damage value ω at any given time can be obtained by integrating over time using formula (4):

[0084]

[0085] If the calculated creep rupture life of the base material and weld joint under corresponding conditions in a lead-bismuth environment matches the creep life design curve of the base material and weld joint in a lead-bismuth environment, then the calculated creep rupture factor C of the weld joint in a lead-bismuth environment is considered to be... cr reliable.

[0086] See Figure 2 This invention discloses a creep failure assessment system for welded joints in a lead-bismuth environment, comprising:

[0087] The acquisition module tests the creep specimens of the welded joint in a lead-bismuth environment to obtain creep life data under different stress levels, and obtains the creep stress-fracture life design curves in the lead-bismuth environment; the welded joint includes the base material, the heat-affected zone and the weld metal.

[0088] The comparison module compares the creep life design curve of the welded joint in the lead-bismuth environment with the average creep stress at the same creep fracture life in the creep life design curve of the base material to obtain the creep fracture factor of the welded joint in the lead-bismuth environment.

[0089] The first establishment module establishes a creep constitutive model based on creep test data of lead-bismuth environment of base material and weld metal.

[0090] The second establishment module establishes a numerical model of the welded joint creep specimen based on the geometric parameters of the welded joint creep specimen under lead-bismuth environment.

[0091] The verification module couples the creep fracture factor into the creep constitutive model and uses the numerical model of the welded joint creep specimen to obtain the creep fracture life of the base material and the welded joint under lead-bismuth conditions, thereby verifying the reliability of the creep fracture factor of the welded joint under lead-bismuth conditions; if the fatigue failure factor is deemed reliable, the creep failure factor of the welded joint under lead-bismuth conditions is determined.

[0092] Example:

[0093] This invention employs a method for assessing creep failure of welded joints in a lead-bismuth environment, the method comprising the following steps:

[0094] Step 1: A series of high-temperature creep rupture tests were conducted on the P92 base material under stress conditions of 160 MPa, 170 MPa, and 180 MPa in a lead-bismuth environment to obtain creep strain-time curves under different stresses. For example... Figure 3 As shown, the creep stress-fracture life design curves of P92 steel under lead-bismuth environment are obtained by sorting out the creep life under different temperatures and stress levels.

[0095] Step 2: Process creep specimens from the weld position of the P92 steel welded joint, and carry out high-temperature creep fracture tests under stress conditions of 160MPa, 170MPa and 180MPa in a lead-bismuth environment to obtain the creep stress-fracture life design curve of the weld in the lead-bismuth environment.

[0096] Step 3: Creep specimens were taken from the fully penetrated transverse butt weld joint of P92 steel. The creep specimens included the base material and part of the weld. A series of high-temperature creep rupture tests were conducted under the same stress control in a lead-bismuth environment. The creep stress-fracture life design curve of the P92 steel weld joint in the lead-bismuth environment was obtained by the same processing method as that used to obtain the creep stress-fracture life design curve of P92 steel.

[0097] Step 4: By comparing the average creep stress at the same creep fracture life in the creep life design curve of the P92 welded joint in a lead-bismuth environment with that in the creep life design curve of the P92 base material, the creep fracture factor C of the P92 welded joint is obtained. cr ,Right now

[0098]

[0099] Among them, C cr The creep rupture factor is the value of the P92 homologous steel welded joint in a lead-bismuth environment. The creep life design curve of P92 steel is based on the corresponding creep fracture life. The average creep stress of P92 steel was obtained. The creep life design curve of the P92 steel welded joint is based on the corresponding creep fracture life. The average creep stress of the welded joint was obtained.

[0100] Figure 4 A schematic diagram is given for calculating the creep fracture factor of P92 welded joints under lead-bismuth environment based on the creep life design curves of P92 welded joints and base material under lead-bismuth environment. Considering the different locations where creep fracture failure occurs in P92 steel welded joints under lead-bismuth environment, the stress conditions are divided into different intervals according to the variation trend of creep fracture factor of welded joints under lead-bismuth environment. The least squares method is used to find the relationship between the average creep stress and creep fracture life in each interval to accurately calculate the creep fracture factor of P92 steel welded joints under lead-bismuth environment.

[0101] Step 5: Based on the lead-bismuth environment creep test data of P92 steel base material, weld metal and welded joint given in Steps 1, 2 and 3, analyze the creep strain-time curves under different stress levels, extract creep parameters, and then establish a creep deformation model.

[0102] The creep deformation model is as follows:

[0103]

[0104] Step 6: Based on the geometric parameters of the P92 base material, weld metal and lead-bismuth environment creep test specimens of the welded joint from Steps 1, 2 and 3, establish a numerical model of the welded joint creep specimen with reference to the gauge length, heat-affected zone width, groove type and groove size of the creep specimen.

[0105] Based on the gauge length, heat-affected zone width, groove type, and groove size of the actual welded joint creep specimen, the material properties are set as base metal, heat-affected zone, and weld in the corresponding regions of the numerical model of the welded joint creep specimen. The obtained creep constitutive model parameters are applied to the base metal and weld to establish the numerical model of the welded joint creep specimen.

[0106] Step 6, Figure 5 The calculation results of the creep deformation constitutive model of P92 steel base material established using the numerical model of welded joint under different stress control are presented. Based on the ductility exhaustion theory, as shown in equations (2)-(4), the creep fracture factor C of P92 steel welded joint calculated in step 3 is... cr A creep constitutive model is obtained by coupling to the creep constitutive model to obtain the creep constitutive model of the heat-affected zone. A creep damage model is established based on the ductility exhaustion theory. Creep failure is considered to occur when the damage value ω reaches 0.99. The creep fracture life of P92 steel base material and welded joint under corresponding conditions in a lead-bismuth environment is calculated using a numerical model of the welded joint creep specimen. Figure 6 As shown, the application of the creep fracture factor for P92 steel welded joints in a lead-bismuth environment can bring the creep life design point of the P92 steel welded joint back to near the creep life design curve of P92 steel. This method can effectively assess the creep failure of P92 steel welded joints in a lead-bismuth environment.

[0107] The coupled creep deformation model is as follows:

[0108]

[0109] The theory of ductility depletion includes:

[0110]

[0111] in, For creep damage rate, and These represent creep strain rate and multiaxial creep fracture strain, respectively. The relationship between the stress state of the current infinitesimal element and the uniaxial fracture strain is related to the stress state and the uniaxial fracture strain. The Cocks-Ashby model is used to describe this relationship:

[0112]

[0113] Where, σ m It is hydrostatic pressure, σ e It is the equivalent stress, σ m / σ e It is stress triaxiality, ε f It is uniaxial fracture strain;

[0114] The damage value ω at any given time can be obtained by integrating over time using formula (2):

[0115]

[0116] If the calculated creep rupture life of the base material and weld joint under corresponding conditions in a lead-bismuth environment matches the creep life design curve of the base material and weld joint in a lead-bismuth environment, then the calculated creep rupture factor C of the weld joint in a lead-bismuth environment is considered to be... cr reliable.

[0117] This invention provides a terminal device. The terminal device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0118] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0119] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0120] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0121] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0122] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0123] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for assessing creep failure of welded joints in a lead-bismuth environment, characterized in that, include: Creep specimens of welded joints were tested in a lead-bismuth environment to obtain creep life data under different stress levels, and creep stress-fracture life design curves in the lead-bismuth environment were obtained respectively; the welded joint includes base metal, heat-affected zone and weld metal; The creep fracture factor of the welded joint in the lead-bismuth environment is obtained by comparing the average creep stress at the same creep fracture life in the creep life design curve of the base material with the creep life design curve of the welded joint in the lead-bismuth environment. A creep constitutive model was established based on creep test data of lead-bismuth environment of base material and weld metal; A numerical model of the creep specimen of the welded joint was established based on the geometric parameters of the creep specimen of the welded joint under lead-bismuth environment. The creep fracture factor is coupled into the creep constitutive model, and the creep fracture life of the base material and the weld joint under lead-bismuth environment is obtained using the numerical model of the weld joint creep specimen. This verifies the reliability of the creep fracture factor of the weld joint under lead-bismuth environment. If the fatigue failure factor is deemed reliable, the creep failure factor of the weld joint under lead-bismuth environment is determined.

2. The method for assessing creep failure of welded joints in a lead-bismuth environment according to claim 1, characterized in that, The creep specimens of the welded joints were tested in a lead-bismuth environment to obtain creep life data under different stress levels. Creep stress-fracture life design curves in the lead-bismuth environment were then obtained, specifically as follows: High-temperature creep fracture test was carried out on creep specimens of the base material of the welded joint under lead-bismuth environment to obtain creep strain-time curves under different stresses; the creep life under various stress levels was integrated to obtain the creep stress-fracture life design curve of the base material. Creep specimens were processed from the weld seam of the welded joint, and high-temperature creep fracture tests were carried out on the deposited metal under different stress conditions in a lead-bismuth environment to obtain the creep strain-time curves of the weld seam under different stress levels in a lead-bismuth environment. High-temperature creep endurance tests with different stress controls were conducted on the creep specimens of the welded joints in a lead-bismuth environment; the creep stress-fracture life design curve of the welded joints in the lead-bismuth environment was obtained by the same processing method as that used to obtain the creep stress-fracture life design curve of the base material.

3. The method for assessing creep failure of welded joints in a lead-bismuth environment according to claim 2, characterized in that, The creep fracture factor of the welded joint in the lead-bismuth environment is obtained by comparing the creep life design curve of the welded joint in the lead-bismuth environment with the creep life design curve of the base material at the same creep fracture life. Specifically: Among them, C cr The creep rupture factor of the welded joint in a lead-bismuth environment. The creep life design curve is based on the corresponding creep fracture life. The obtained creep stress of the base material, The creep life design curve of the welded joint is based on the corresponding creep fracture life. The creep stress of the welded joint was obtained.

4. The method for assessing creep failure of welded joints in a lead-bismuth environment according to claim 3, characterized in that, Based on the creep test data of lead-bismuth environment of the base material and weld metal, a creep constitutive model is established, specifically as follows: Based on creep test data of lead-bismuth in the base material and weld metal, we analyzed the creep strain-time curves under different stress levels, extracted creep parameters, and established a creep deformation model. The creep deformation model is as follows: in, The creep strain rate represents the steady-state stage, / h; σ is the applied stress level, MPa; B is the creep strain coefficient; n is the creep strain exponent.

5. The method for assessing creep failure of welded joints in a lead-bismuth environment according to claim 4, characterized in that, The numerical model of the welded joint creep specimen, based on the geometric parameters of the welded joint creep specimen under lead-bismuth environment, is established as follows: Based on the gauge length, heat-affected zone width, groove type, and groove size of the actual welded joint creep specimen, the material properties are set as base metal, heat-affected zone, and weld in the corresponding region of the numerical model of the welded joint creep specimen. The obtained creep constitutive model parameters are applied to the base metal and weld to establish the numerical model of the welded joint creep specimen.

6. The method for assessing creep failure of welded joints in a lead-bismuth environment according to claim 5, characterized in that, The coupling of the creep fracture factor to the creep constitutive model to verify the reliability of the creep fracture factor of the welded joint in the lead-bismuth environment is specifically as follows: Creep fracture factor C cr A creep constitutive model of the heat-affected zone (HAZ) is obtained by coupling the model to the creep constitutive model of the base material and applied to the HAZ region of the numerical model of the weld joint. A creep damage model is established based on the ductility depletion theory. Creep failure is considered to occur when the damage value ω reaches 0.

99. The creep fracture life of the base material and the weld joint under lead-bismuth conditions is calculated using the numerical model of the weld joint creep specimen. The creep life design curves of the base material and the weld joint under lead-bismuth conditions are compared with those to verify the reliability of the calculated creep fracture factor of the weld joint under lead-bismuth conditions. The coupled creep deformation model is as follows: The theory of ductility depletion includes: in, For creep damage rate, and These represent creep strain rate and multiaxial creep fracture strain, respectively. The relationship between the stress state of the current infinitesimal element and the uniaxial fracture strain is related to the stress state and the uniaxial fracture strain. The Cocks-Ashby model is used to describe this relationship: Where, σ m It is hydrostatic pressure, σ e It is the equivalent stress, σ m / σ e It is stress triaxiality, ε f It is uniaxial fracture strain; The damage value ω at any given time can be obtained by integrating over time using formula (4): If the calculated creep rupture life of the base material and weld joint under corresponding conditions in a lead-bismuth environment matches the creep life design curve of the base material and weld joint in a lead-bismuth environment, then the calculated creep rupture factor C of the weld joint in a lead-bismuth environment is considered to be... cr reliable.

7. A creep failure assessment system for welded joints in a lead-bismuth environment, characterized in that, include: The acquisition module tests the creep specimens of the welded joint in a lead-bismuth environment to obtain creep life data under different stress levels, and obtains the creep stress-fracture life design curves in the lead-bismuth environment; the welded joint includes the base material, the heat-affected zone and the weld metal. The comparison module compares the creep life design curve of the welded joint in the lead-bismuth environment with the average creep stress at the same creep fracture life in the creep life design curve of the base material to obtain the creep fracture factor of the welded joint in the lead-bismuth environment. The first establishment module establishes a creep constitutive model based on creep test data of lead-bismuth environment of base material and weld metal. The second establishment module establishes a numerical model of the welded joint creep specimen based on the geometric parameters of the welded joint creep specimen under lead-bismuth environment. The verification module couples the creep fracture factor into the creep constitutive model and uses the numerical model of the welded joint creep specimen to obtain the creep fracture life of the base material and the welded joint under lead-bismuth conditions, thereby verifying the reliability of the creep fracture factor of the welded joint under lead-bismuth conditions; if the fatigue failure factor is deemed reliable, the creep failure factor of the welded joint under lead-bismuth conditions is determined.

Images