Method for converting u-shaped and v-shaped impact energy of a nuclear-grade cast main pipe after service
Patent Information
- Application Number
- CN202510526431.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2026-10-16
- Estimated Expiration
- 2045-04-25
AI Technical Summary
尽管V形缺口试样是当今采用的主要形式，但是仍然存在许多不同的试样版本
[0016] The beneficial effects of this invention are: establishing a correlation formula between the U-shaped and V-shaped impact energies of nuclear-grade cast main pipelines after service, based on the U-shaped impact energy C in the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U The V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated was calculated based on the correlation formula. V It can convert and compare the impact energy types of different manufacturing standards, testing standards, and evaluation models.
Smart Images
Figure CN120527050B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nuclear-grade cast main pipeline technology, specifically relating to a method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline has entered service. Background Technology
[0002] Cast austenitic stainless steel is widely used in the manufacture of pressure boundary components (CASS) of the primary loop in light water reactors, such as main piping, due to its excellent machinability, corrosion resistance, and mechanical properties. However, these CASS components of the light water reactor coolant system, due to their austenitic and ferritic dual-phase structure, will experience thermal aging embrittlement during long-term operation in high-temperature environments of 290-320℃, leading to a decrease in fracture toughness and an increased risk of brittle fracture under external forces.
[0003] The most common test for assessing the fracture toughness parameters of structural components such as main piping is the Charpy V-notch impact test, which is used as an evaluation metric in almost all structural integrity assessment procedures. The preferred notch geometry is the V-notch, but other geometries such as the U-notch are sometimes used. The root radius of the U-notch is typically 1 mm, and the ligament width is 5 mm or 8 mm, while the root radius of the V-notch is 0.25 mm, and the ligament width is 8 mm. Although the V-notch specimen is the dominant form used today, many different specimen versions still exist. More importantly, some structural components use U-notch specimen data for initial performance assessment, while later evaluation models use V-notch specimen data. For example, RCC-M 3403, "Cast elbows and nozzles made of molybdenum-free chromium-nickel austenitic-ferritic stainless steel – piping for pressurized water reactor coolant systems" (1993 edition), requires U-notch specimen data for the impact energy index of nuclear-grade cast main piping, while RCC-M 3403 (2000 edition) changed the impact energy index requirement to use V-notch specimen data. In this case, it is necessary to obtain the U-shaped and V-shaped impact energy conversion methods after the nuclear-grade cast main pipeline has been put into service, based on impact sample data with different notch shapes. Summary of the Invention
[0004] The purpose of this invention is to provide a method for converting U-shaped and V-shaped impact energies after a nuclear-grade cast main pipeline has entered service. This method involves establishing a correlation between the U-shaped and V-shaped impact energies of the nuclear-grade cast main pipeline after service, thereby obtaining the U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U The U-shaped impact energy C in the completion report or test report of the nuclear-grade cast main pipeline to be evaluated U Substituting the correlation formula between U-shaped and V-shaped impact energies, calculate the V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated. V .
[0005] The technical solution of the present invention is as follows: A method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline has entered service, comprising the following steps:
[0006] Step 11: Establish the correlation formula for the U-shaped and V-shaped impact energies of the nuclear-grade cast main pipeline after it enters service;
[0007] Step 12: Obtain the U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U ;
[0008] Step 13: The U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated... U Substituting the correlation formula between U-shaped and V-shaped impact energies, calculate the V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated. V .
[0009] The correlation formula between U-shaped and V-shaped impact energies in step 11 includes room temperature impact energy testing of the nuclear-grade cast main pipeline in its original state and room temperature impact energy testing after accelerated thermal aging test.
[0010] After obtaining the impact energy in step 11, the correlation formula between U-shaped and V-shaped impact energies is established.
[0011] The room temperature impact energy test includes two types: impact energy tests for standard U-shaped and V-shaped specimens, with corresponding impact energies C0 and C1, respectively. U C V The ligament width of the standard U-shaped impact specimen is 5 mm, the ligament width of the standard V-shaped impact specimen is 8 mm, and the radius of curvature of the pendulum hammer edge for impact energy testing is 2 mm.
[0012] The association formula is as follows:
[0013] C V / C Vint =a(C U / C Uint )+b(C U / C Uint )^2 (1)
[0014] Among them, C V C U These represent the impact energies of standard V-shaped and U-shaped specimens after accelerated thermal aging tests, respectively, C. Vint C Uint 1 and 2 are the initial impact energies of the standard V-shaped and U-shaped specimens in their original state, respectively, and a and b are material-related numerical fitting parameters.
[0015] a and b employ the least squares method, minimizing the experimental data point X = C. U / C Uint Y = CV / C Vint The sum of squared residuals between the fitted curve and the relationship (1) determines the parameters of the optimal fitted curve.
[0016] The beneficial effects of this invention are: establishing a correlation formula between the U-shaped and V-shaped impact energies of nuclear-grade cast main pipelines after service, based on the U-shaped impact energy C in the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U The V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated was calculated based on the correlation formula. V It can convert and compare the impact energy types of different manufacturing standards, testing standards, and evaluation models. Attached Figure Description
[0017] Figure 1 This is a flowchart of a method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline has been put into service, as proposed in this invention.
[0018] Figure 2 This is a schematic diagram of a standard U-shaped impact specimen (ligament width is 5mm);
[0019] Figure 3 This is a schematic diagram of a standard V-shaped impact specimen (ligament width is 8mm).
[0020] Figure 4 The normalized V-shaped impact energy C of a nuclear-grade cast main pipe V / C Vint and U-shaped impact energy C U / C Uint Comparison curves.
[0021] Figure 5 This is a comparison chart of predicted and experimental values. Detailed Implementation
[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0023] This invention provides a method for converting U-shaped and V-shaped impact energies after a nuclear-grade cast main pipeline enters service. This method establishes a correlation between the U-shaped and V-shaped impact energies after the nuclear-grade cast main pipeline enters service, based on the U-shaped impact energy C in the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U The impact energy C U Substituting the correlation formula between U-shaped and V-shaped impact energies, calculate the V-shaped impact energy C of the nuclear-grade cast main pipe. V The method and process are as follows Figure 1 As shown.
[0024] A method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline enters service includes the following steps:
[0025] Step 11: Establish the correlation formula for the U-shaped and V-shaped impact energies of the nuclear-grade cast main pipeline after it enters service;
[0026] Among them, the correlation formula between U-shaped and V-shaped impact energies includes room temperature impact energy testing of nuclear-grade cast main pipelines in their original state and room temperature impact energy testing after accelerated thermal aging tests. After obtaining the impact energy, the correlation formula between U-shaped and V-shaped impact energies is established.
[0027] Room temperature impact energy testing includes two types: impact energy testing of standard U-shaped and V-shaped specimens, with corresponding impact energies C and C, respectively. U C V The ligament width of the standard U-shaped impact specimen is 5 mm, the ligament width of the standard V-shaped impact specimen is 8 mm, and the radius of curvature of the pendulum hammer edge for impact energy testing is 2 mm.
[0028] The relationship formula is:
[0029] C V / C Vint =a(C U / C Uint )+b(C U / C Uint )^2 (1)
[0030] Among them, C V C U These represent the impact energies of standard V-shaped and U-shaped specimens after accelerated thermal aging tests, respectively, C. Vint C Uint , representing the initial impact energies of standard V-shaped and U-shaped specimens in their original states, respectively; a and b are material-related numerical fitting parameters. a and b are calculated using the least squares method, minimizing the impact energy of the experimental data point X = C. U / C Uint Y = C V / C Vint The sum of squared residuals between the fitted curve and the relationship (1) determines the parameters of the optimal fitted curve.
[0031] Step 12: Obtain the U-shaped impact energy C from the manufacturing completion report or test report of the nuclear-grade cast main pipeline to be evaluated after it leaves the factory. U ;
[0032] Step 13: The U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated... U Substituting the correlation formula (1) between U-shaped and V-shaped impact energies, the V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated is calculated. V .
[0033] Example: Accelerated thermal aging tests were conducted on a nuclear-grade statically cast stainless steel Z3CN20-09M main pipeline at 400℃ to simulate an equivalent service environment. Then, impact energy tests were performed on standard U-shaped and V-shaped specimens in their original state and after thermal aging for 100, 500, 1000, 2000, 5000, and 10000 hours. The U-shaped and V-shaped impact energies were obtained, and numerical fitting parameters a and b were calculated to derive the correlation between the U-shaped and V-shaped impact energies. Based on the U-shaped impact energy C in the completion report or test report of the nuclear-grade cast main pipeline to be evaluated... U The U-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated U Converted into V-shaped impact energy C V .
[0034] 1. Accelerated thermal aging tests were conducted on a nuclear-grade static cast stainless steel main pipeline Z3CN20-09M at 400℃ to simulate the equivalent service environment. The thermal aging time nodes were 100, 500, 1000, 2000, 5000 and 10000 hours, for a total of 6.
[0035] 2. Preparation of Standard U-shaped and V-shaped Specimens: The original state and the node specimens subjected to the above-mentioned heat aging of 100, 500, 1000, 2000, 5000, and 10000 hours are processed into standard U-shaped and V-shaped specimens. Both types of specimens have a width and thickness of 10 mm and a length of 55 mm. The ligament width of the standard U-shaped impact specimen is 5 mm. Figure 2 As shown, the ligament width of a standard V-type impact specimen is 8 mm. Figure 3 As shown.
[0036] 3. Impact Energy Test: Standard U-shaped and V-shaped specimens in their original state and after six different thermal aging time points were subjected to room temperature impact energy tests to obtain the impact energy data C for each time point. U C V The pendulum hammer edge curvature radius for the impact energy test was 2mm, and the U-shaped impact energy C was obtained respectively. U V-shaped impact energy C V ,。 7 experimental data points (X=C U / C Uint Y = C V / C Vint The values are (1.00, 1.00), (1.01, 0.96), (0.94, 0.64), (0.82, 0.54), (0.56, 0.42), (0.47, 0.33) and (0.38, 0.31), respectively.
[0037] 4. Relationship between U-shaped and V-shaped impact energies:
[0038] C V / C Vint =a(C U / C Uint )+b(C U / C Uint )^2 (1)
[0039] Where C V C U These represent the impact energies of standard V-shaped and U-shaped specimens after accelerated thermal aging tests, respectively, C. Vint C Uint These are the initial impact energies of standard V-shaped and U-shaped specimens in their original state, respectively, in J / cm². 2 By minimizing the above 7 experimental data points (X=C) U / C Uint Y = C V / C Vint The sum of squared residuals between eight data points (X=0, Y=0) and the fitted curve relationship (1) is used to determine the optimal fitted curve parameters a=0.49, b=0.38, and the error R of the curve relationship. 2 =0.90, V-shaped impact energy C V / C Vint and U-shaped impact energy C U / C Uint Comparison curves as follows Figure 4 As shown.
[0040] 5. Obtain the U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U =100.00J / cm 2 ; and it is known that the impact energies of the standard V-shaped and U-shaped specimens in their original states are C, respectively. Vint =436J / cm 2 C Uint =297J / cm 2 .
[0041] 6. The U-shaped impact energy C in the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U Substituting the correlation formula (1) between U-shaped and V-shaped impact energies, the V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated is calculated. V =91 / cm 2 .
[0042] 7. Apply the above relationship to C V / C Vint The predicted values and experimental values for example Figure 5 As shown, 50% of the data prediction errors are within ±10%, 62.5% of the data prediction errors are within ±20%, and the prediction errors for all data are within ±25%.
[0043] The parts of this invention not disclosed in detail are well-known technologies in the field.
[0044] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.
Claims
1. A method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline has entered service, characterized in that... Includes the following steps: Step 11: Establish the correlation formula for the U-shaped and V-shaped impact energies of the nuclear-grade cast main pipeline after it enters service; The correlation between U-shaped and V-shaped impact energies in step 11 includes room temperature impact energy testing of the nuclear-grade cast main pipeline in its original state and room temperature impact energy testing after accelerated thermal aging tests; after obtaining the impact energy in step 11, the correlation between U-shaped and V-shaped impact energies is established; the room temperature impact energy test includes two types, namely, impact energy testing of standard U-shaped and V-shaped samples, with corresponding impact energies C and C, respectively. U C V The ligament width of the standard U-shaped impact specimen is 5 mm, the ligament width of the standard V-shaped impact specimen is 8 mm, and the radius of curvature of the pendulum hammer edge for impact energy testing is 2 mm. Step 12: Obtain the U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated. U ; Step 13: The U-shaped impact energy C from the completion report or test report of the nuclear-grade cast main pipeline to be evaluated... U Substituting the correlation formula between U-shaped and V-shaped impact energies, calculate the V-shaped impact energy C of the nuclear-grade cast main pipe to be evaluated. V ; The association formula is as follows: C V / C Vint = a (C U / C Uint )+ b (C U / C Uint )^2 (1), Among them, C V C U These represent the impact energies of standard V-shaped and U-shaped specimens after accelerated thermal aging tests, respectively, C. Vint C Uint The figures represent the initial impact energies of standard V-shaped and U-shaped specimens in their original states. a , b These are the numerical fitting parameters related to the material.
2. The method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline enters service, as described in claim 1, is characterized in that: a , b It is calculated using the least squares method.
3. The method for converting U-shaped and V-shaped impact energy after a nuclear-grade cast main pipeline enters service, as described in claim 2, is characterized in that: By minimizing the experimental data point X=C U / C Uint Y=C V / C Vint The sum of squared residuals between the fitted curve and the relationship (1) determines the parameters of the optimal fitted curve.