Sampling method for cylindrical forge piece of reactor pressure vessel

Abstract

The invention provides a sampling method for a cylindrical forge piece of a reactor pressure vessel, and relates to the technical field of manufacturing and production of cylindrical forge pieces of reactor pressure vessels. The sampling method comprises the following steps: according to the shape characteristics of the cylindrical forge piece, cutting samples at different parts of a nozzle end and a riser end of the cylindrical forge piece, carrying out chemical component analysis, metallographic inspection and mechanical property test on the samples at each part, and reflecting the quality of the cylindrical forge piece according to the performance test result of each part. By cutting the most representative sampling point, various technical indexes of the cylindrical forge piece of the reactor pressure vessel in the process evaluation stage can be comprehensively and effectively evaluated, and meanwhile, the rationality and feasibility of the manufacturing process of the cylindrical forge piece can be verified.

Description

Technical Field

[0001] The invention relates to the technical field of reactor pressure vessel cylindrical forging manufacturing and production, in particular to a method for sampling reactor pressure vessel cylindrical forgings. Background Art

[0002] At present, the world has entered a new round of nuclear power development. Many countries are actively preparing to build new nuclear power units. However, the production capacity of large castings and forgings for nuclear islands around the world is very limited, and the manufacturing technology is mainly controlled by a few manufacturers, which can no longer meet the needs of nuclear power development around the world. In combination with our country's policy of developing nuclear power and localizing nuclear power equipment, in order to achieve the goals of our country's nuclear power development plan, it is necessary to realize the localization of reactor pressure vessel cylindrical forgings. To truly realize the localization of cylindrical forgings and achieve mass production under the condition of ensuring quality, it is necessary not only for manufacturers to innovate in manufacturing technology, but also to successfully complete the technical evaluation of the manufacturing process of large castings and forgings for nuclear islands. Of course, the process evaluation of reactor pressure vessel cylindrical forgings must also be carried out.

[0003] The relevant nuclear power specification RCC-M (abbreviation for "Rules for the Design and Construction of Mechanical Equipment for Pressurized Water Reactor Nuclear Island") only has assessment requirements, but no specific assessment plan and assessment specifications. Assessment itself is a comprehensive multidisciplinary nuclear power general technology and one of the core technologies for nuclear power autonomy. It involves many disciplines such as manufacturing process technology, metal materials, physical and chemical testing, non-destructive testing, design analysis, fracture mechanics, life management and engineering management. Through equipment manufacturing process assessment, it verifies the manufacturer's manufacturing and management capabilities, as well as the overall and intrinsic quality of these parts or products manufactured by the manufacturer to meet the requirements of design and nuclear safety, ensure the repeatability of manufacturing quality, effectively reduce inspection items, reduce manufacturing costs and shorten manufacturing cycles, thereby providing strong conditions for manufacturers to mass-produce important parts of the nuclear island.

[0004] Reactor pressure vessel cylindrical forgings are in high temperature and high pressure environment for a long time, which requires the vessel to have high strength. The quality of cylindrical forgings directly determines whether the pressure vessel can meet the standards. Therefore, the requirements and inspections for its internal quality are very strict. In addition to the inspections of chemical composition, mechanical properties, metallographic structure, grain size, inclusions, etc., non-destructive inspections such as ultrasonic flaw detection must be carried out according to the requirements of the procurement specifications. Single defects and intensive defects cannot exceed the specified range to ensure the overall quality of the forgings. Therefore, it is very necessary to be able to comprehensively and effectively evaluate the various technical indicators of the reactor pressure vessel cylindrical forgings in the process evaluation stage. Summary of the invention

[0005] The object of the present invention is to provide a sampling method for reactor pressure vessel cylindrical forgings, wherein the sampling points cover the typical areas of the forgings, and can comprehensively and effectively evaluate the various technical indicators of the reactor pressure vessel cylindrical forgings in the process evaluation stage, while verifying the rationality and feasibility of the cylindrical forgings manufacturing process.

[0006] In order to evaluate the mechanical properties of barrel forgings, such as strength, toughness and hardness, it is necessary to cut specimens at specific locations. These locations include high stress areas of barrel forgings, areas with minimal deformation, and areas near the riser end of barrel forgings. Through testing at these locations, we can fully understand the mechanical properties of barrel forgings under different conditions, so as to evaluate whether they meet the design requirements and use conditions.

[0007] For the parts with streamline requirements of cylindrical forgings, the selection of sampling positions is particularly important. The streamline of cylindrical forgings is formed by the elongation of metal grains along the deformation direction during the forging process, which has an important influence on the mechanical properties of cylindrical forgings. Therefore, sampling in the parts with streamline requirements can evaluate the structural integrity and mechanical properties of cylindrical forgings.

[0008] In the macrostructure inspection, the sampling position is selected at the required streamline of the cylindrical forging or on the section that best reflects the reasonable flow direction of the metal, and the transverse macrostructure test piece should be taken at the largest section as much as possible. The macrostructure inspection focuses on the analysis of the microstructure, and the sampling position is usually at the largest section or high stress part of the cylindrical forging to facilitate the analysis of microscopic characteristics such as non-metallic inclusions and grain size.

[0009] In addition, since the surface of the cylindrical forging is in contact with the die during the forging process, there is a lot of friction during the relative movement between the two, which makes the local temperature too high, resulting in a certain degree of tissue damage on the surface of the forging blank (coarse grains, burr cracks, etc.). In addition, during the heat treatment process, a layer of shallow overburned tissue will form on the surface of the cylindrical forging due to the excessively high local temperature. This tissue can become a crack source, resulting in a decrease in the performance of the cylindrical forging. Therefore, the performance of the sample close to the surface of the cylindrical forging is poor, and it is not suitable to be used as an evaluation sample to evaluate the true performance of the cylindrical forging. However, since the performance of the sample at the surface of the cylindrical forging is related to the overall quality of the cylindrical forging, it is usually sampled internally after the surface sampling, which is cumbersome and has high sampling costs.

[0010] Therefore, the present invention provides a method for sampling a reactor pressure vessel cylindrical forging, comprising the following steps:

[0011] S1. Sampling at the nozzle end of the cylindrical forging:

[0012] S11, first cut the first sample ring, the second sample ring, and the third sample ring in sequence at the position of 1 / 4 wall thickness, 1 / 2 wall thickness, and 3 / 4 wall thickness from the inner surface of the nozzle end, and the thickness of the three sample rings is 40 mm;

[0013] S12, cutting a plurality of samples in sections along the circumferential direction from the first sample ring, the second sample ring and the third sample ring, wherein the center of each sample ring coincides with the center of the end face of the nozzle end of the forging;

[0014] S2. Sampling at the riser end of the cylindrical forging:

[0015] S21. First, cut the fourth test ring, the fifth test ring, and the sixth test ring in sequence at the position of 1 / 4 wall thickness, 1 / 2 wall thickness, and 3 / 4 wall thickness from the inner surface of the riser end. The thickness of the three test rings is 40 mm. The distance between the inner diameter of the fourth test ring and the inner diameter of the forging is 80 mm. The distances between the fourth test ring, the fifth test ring, and the sixth test ring are all 100 mm.

[0016] S21. Cut a plurality of samples in three layers evenly spaced along the thickness direction of the fourth sample ring, the fifth sample ring and the sixth sample ring, and cut a plurality of samples in each layer along the circumferential direction, and the center of each sample ring coincides with the center of the end face of the riser end of the forging.

[0017] The nozzle end is located at the bottom of the ingot, that is, the tail part of the ingot, and is the entrance when the ingot is poured. Therefore, this area solidifies first and has relatively good quality. During the forging process, the nozzle end is cut off in a small proportion, and can even be directly upset to improve the yield rate. However, the nozzle end has serious segregation. The present invention performs circumferential layered sampling at different wall thickness positions, and the multi-layer test samples can fully reflect the performance of the nozzle end, so as to provide a basis for the overall quality assessment of the cylindrical forging.

[0018] The riser end is located at the top of the ingot. It is a specially designed cavity for storing molten metal. It is used to compensate for the shrinkage that may occur during the casting process. It prevents shrinkage cavities, shrinkage, exhaust and slag collection. Since the riser area solidifies last, the quality of this area is relatively poor, containing more impurities and defects, such as bubbles, shrinkage cavities, etc., and the loose area is serious. By limiting the thickness, distance and size of the sample ring, the present invention allows the cut sample to cover the entire area of ​​the riser end (including circumferential and axial directions), which can more comprehensively reflect the mechanical and physical and chemical properties of the riser end, so as to provide a basis for the overall quality assessment of the cylindrical forging.

[0019] Furthermore, the seventh, eighth and ninth sample rings are cut from the cylindrical forging with an opening at the positions of 1 / 4 wall thickness, 1 / 2 wall thickness and 3 / 4 wall thickness from the inner surface for sampling.

[0020] Among them, the seventh sample ring, the eighth sample ring and the ninth sample ring all take at least two samples along the circumferential direction, and the interval between the two samples is 40-80 mm.

[0021] The cut specimens are subjected to performance tests under HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile test, at least 18 specimens are used for impact test, at least 24 specimens are used for KV-T curve test, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determination of non-metallic inclusions, and at least 1 specimen is used for determination of grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact test, at least 6 specimens are used for impact test, at least 24 specimens are used for KV-T curve test, at least 8 specimens are used for drop hammer test, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determination of non-metallic inclusions, and at least 1 specimen is used for determination of grain size.

[0022] The tensile specimen size is φ10mm×50mm, the impact specimen size is 10mm×10mm×55mm, the drop hammer specimen size is 80mm×10mm×4mm, the specimen block size for chemical composition analysis and non-metallic inclusions is 25mm×25mm×30mm, and the grain size specimen block size is 25mm×25×30mm.

[0023] By cutting the samples in layers at the limited thickness of the nozzle end, the riser end and the opening position, it can be ensured that the sampling position of the sample is in the well-deformed area of ​​the cylindrical forging, and at the geometric center of the forging blank, covering the circumferential, circumferential and radial directions of the cylindrical forging, which can truly reflect the performance of the final cylindrical forging. By limiting the sample size, the chance of avoiding small defects (inclusions, eddy currents, etc.) during the tensile, impact, drop hammer and KV-T curve tests is smaller, and more cylindrical forging body material tissues can be collected; chemical composition analysis, non-metallic inclusions and grain size detection can prevent the omission of small defects, collect more accurate forging body material tissues, so that the performance test can more comprehensively and truly reflect the performance of the cylindrical forging. Limiting the number of samples can effectively overcome the inaccurate quality assessment of cylindrical forgings caused by a small number of samples, and can avoid the problem of waste of manpower, materials and time caused by a large number of samples. Among them, the centers of the seventh sample ring, the eighth sample ring and the ninth sample ring are located on the axis of the opening.

[0024] Furthermore, the cylindrical forging includes a core section cylinder, a lower head transition section and a pipe section cylinder. Among them, at least 48 core section cylinder samples in the HTMP state are used for KV-T curve test, and at least 12 samples in the HTMP+SSRHT state are used for impact test and at least 48 are used for KV-T curve test.

[0025] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0026] In the present invention, a comprehensive technical evaluation is carried out on low-alloy steel cylindrical forgings of reactor pressure vessels. The evaluation covers the entire process of forging manufacturing, and can comprehensively and effectively evaluate various technical indicators in the process evaluation stage of reactor pressure vessel cylindrical forgings, forming a complete and standardized comprehensive sampling method, which can verify the rationality and feasibility of the cylindrical forging manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross-sectional view of the core section of the reactor pressure vessel;

[0028] Figure 2 A top view of a reactor pressure vessel core section cylinder;

[0029] Figure 3 It is a cross-sectional view of the transition section of the lower head of the reactor pressure vessel;

[0030] Figure 4 It is a top view of the transition section of the lower head of the reactor pressure vessel;

[0031] Figure 5 It is a cross-sectional view of the reactor pressure vessel nozzle section cylinder;

[0032] Figure 6 It is a cross-sectional view of the reactor pressure vessel take-over section cylinder AA. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0034] For low alloy steel cylindrical forgings of reactor pressure vessels, the most commonly used process flow is:

[0035] Smelting - forging - post-forging heat treatment - rough machining - performance heat treatment - finishing. The sampling method of this embodiment is applicable to the above process. Taking the core section cylinder of the Hualong No. 1 reactor pressure vessel as an example, its specific implementation method is as follows:

[0036] (1) Smelting stage

[0037] The smelting of steel should adopt electric furnace (EF) to smelt molten steel, and then vacuum refining in refining furnace. The steel ingot is cast by 3 bags of molten steel by vacuum pouring process, and the total weight of the steel ingot is 360 tons. Among them, the method of rough refining in electric furnace (EF) + vacuum refining and vacuum pouring process are key processes for evaluation; the number of 3 bags of cascade casting is the key parameter for evaluation, and the weight of the steel ingot is 360 tons (allowable deviation ±7%). At the same time, the impurity elements of the raw materials for forgings should be strictly controlled, and samples should be taken for smelting chemical composition analysis. The chemical composition needs to detect the content of C, Si, Mn, P, S, Cr, Ni, Mo, V, Cu, Al, Co, As, Sn, Sb, B, N, H, and O elements.

[0038] (2) Forging stage

[0039] The forging process and forging sequence of the core section cylinder forgings are as follows:

[0040] Gas cutting nozzle, riser and ingot body discard - upsetting - punching - drawing - hole expansion.

[0041] The forging process and forging sequence of forgings are key processes for evaluation. During forging, sufficient pressure should be ensured to deform the steel ingot deeply and complete plastic deformation under reasonable stress state to make the structure dense.

[0042] The amount of steel ingot removed should be sufficient, and the weight of the steel ingot and the percentage of weight removed should be recorded and archived. For the core section cylinder in the area subject to strong irradiation, the amount of steel ingot head removed should be at least 13%, and the amount of steel ingot tail removed should be at least 7%. The amount of head and tail removed from forgings is the key parameter for evaluation. The total forging ratio of forgings should be greater than 3, which is the key parameter for evaluation.

[0043] (3) Post-forging heat treatment stage

[0044] The normalizing + tempering process is adopted. The forgings are heated to the austenitizing temperature range and kept warm. After full austenitization, they are air-cooled to obtain a uniform and refined structure, and then tempered. The post-forging heat treatment process is the key process for evaluation. The number of heat treatments, normalizing temperature, tempering temperature, and holding time are the key parameters for evaluation. Thermocouples should be placed at the nozzle end and riser end of the forging to ensure that the positions of the expected maximum and minimum temperatures of the forging are covered. The maximum allowable deviation between the actual temperature of different parts of the forging being treated and the specified heat treatment temperature is ±10°C.

[0045] (4) Rough processing stage

[0046] The outer dimensions of the processed forgings should be as close as possible to those of the final product, but sufficient size should be left at the nozzle and riser ends of the forgings to cut test rings for performance testing. At the same time, sufficient margins should be left on the inner and outer walls of the forgings for subsequent defect removal (if any) and finishing processes.

[0047] (5) Performance heat treatment stage

[0048] The forging is heated in an electric furnace to the austenitizing temperature range (850℃~925℃) and kept warm to homogenize the austenite structure, and then quenched to fully transform the structure. Here, a multi-stage austenitizing heat treatment process can be selectively adopted according to the performance requirements of the forging (the forging is heated in an electric furnace to the austenitizing temperature range and kept warm to homogenize the austenite structure, and then quenched; then the forging is reheated to the critical temperature range, partially austenitized, and quenched again).

[0049] After completing the austenitization-quenching cycle, the forging is tempered at 635℃~665℃ to obtain a stable tempered bainite structure. The performance heat treatment process is the key process for evaluation, and the number of heat treatments, quenching temperature, tempering temperature, holding time, heating rate, and cooling rate are the key parameters for evaluation; thermocouples should be placed at the nozzle end and riser end of the forging to ensure that the positions of the expected maximum and minimum temperatures of the forging are covered. The maximum allowable deviation between the actual temperature of different parts of the forging being treated and the specified heat treatment temperature is ±10℃.

[0050] Therefore, the key processes and key parameters for evaluation formulated in this evaluation method are summarized as follows:

[0051] Smelting: smelting process, number of ladles, weight of ingots.

[0052] Forging: forging process, forging sequence, head / tail removal, total forging ratio.

[0053] Post-forging heat treatment: post-forging heat treatment process, number of heat treatments, normalizing temperature, tempering temperature, and holding time.

[0054] Performance heat treatment: performance heat treatment process, number of heat treatments, quenching temperature, tempering temperature, holding time, heating rate, cooling rate.

[0055] Sampling inspection: sample status, sampling location, and sampling quantity.

[0056] Non-destructive testing: acceptance criteria.

[0057] When evaluating key processes, the process method shall not be changed without authorization, otherwise the original forging evaluation results will be invalid. The key parameters of the evaluation are valid within the evaluation approval range, and exceeding the evaluation approval range will cause the original evaluation results to be invalid.

[0058] like Figure 1-6 As shown, this embodiment provides a method for sampling a reactor pressure vessel cylindrical forging, comprising the following steps:

[0059] S1. Sampling at the nozzle end of the forging:

[0060] S11, first cut the first sample ring, the second sample ring, and the third sample ring in sequence at the position of 1 / 4 wall thickness, 1 / 2 wall thickness, and 3 / 4 wall thickness from the inner surface of the nozzle end, and the thickness of the three sample rings is 40 mm;

[0061] S12, cut multiple samples in sections along the circumferential direction on the first sample ring, the second sample ring and the third sample ring, the center of each sample ring coincides with the center of the end face of the nozzle end of the forging, and the sample ring is divided into two sections, with a spacing of 50 mm between each section;

[0062] S2. Sampling at the riser end of the forging:

[0063] S21. First, cut the fourth test ring, the fifth test ring, and the sixth test ring in sequence at the position of 1 / 4 wall thickness, 1 / 2 wall thickness, and 3 / 4 wall thickness from the inner surface of the riser end. The thickness of the three test rings is 40 mm. The distance between the inner diameter of the fourth test ring and the inner diameter of the forging is 80 mm. The distances between the fourth test ring, the fifth test ring, and the sixth test ring are all 100 mm.

[0064] S22, cutting a plurality of samples in three layers evenly spaced along the thickness direction of the fourth sample ring, the fifth sample ring and the sixth sample ring, and cutting a plurality of samples in each layer along the circumferential direction, and the center of each sample ring coincides with the center of the end face of the riser end of the forging;

[0065] S3. Take samples at the opening of the cylindrical forging:

[0066] S31, cutting the seventh sample ring, the eighth sample ring and the ninth sample ring at the position of 1 / 4 wall thickness, 1 / 2 wall thickness and 3 / 4 wall thickness from the inner surface of the opening;

[0067] S32, the seventh sample ring, the eighth sample ring and the ninth sample ring all take at least two samples along the circumferential direction, and the interval between the two samples is 40 mm;

[0068] S33. The cut specimens are subjected to performance tests under HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile test, at least 18 specimens are used for impact test, at least 24 specimens are used for KV-T curve test, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determination of non-metallic inclusions, and at least 1 specimen is used for determination of grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact test, at least 6 specimens are used for impact test, at least 24 specimens are used for KV-T curve test, at least 8 specimens are used for drop hammer test, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determination of non-metallic inclusions, and at least 1 specimen is used for determination of grain size.

[0069] Among them, the tensile test specimen size is φ10mm×50mm, the impact test specimen size is 10mm×10mm×55mm, the drop hammer test specimen size is 80mm×10mm×4mm, the test block size for chemical composition analysis and non-metallic inclusions is 25mm×25mm×30mm, and the test block size for grain size is 25mm×25×30mm. In addition, at least 48 core section cylinder specimens in the HTMP state are used for KV-T curve test, and at least 12 specimens in the HTMP+SSRHT state are used for impact test and at least 48 specimens are used for KV-T curve test.

[0070] The performance tests of the samples in S1, S2 and S3 are carried out in three categories, including chemical composition analysis, metallographic examination and mechanical properties test:

[0071] 1) The chemical composition needs to detect the content of C, Si, Mn, P, S, Cr, Ni, Mo, V, Cu, Al, Co, As, Sn, Sb, B, N, H, and O elements, and calculate the welding reheat crack sensitivity coefficient and carbon equivalent. Special attention should be paid to the control of impurity elements. For cylindrical forgings, the P element content needs to be controlled below 0.006%, the S element content needs to be controlled below 0.005%, and the Cu element content needs to be controlled below 0.05%;

[0072] The chemical composition shall be determined in accordance with the relevant provisions of GB / T 223. Other testing standards and methods with a testing accuracy not less than that of GB / T223 may also be used. If there is a dispute over the test results of a certain element, the test results of GB / T223 shall prevail;

[0073] 2) The metallographic structure should measure the grain size of the material, evaluate the non-metallic inclusions, and provide metallographic photos;

[0074] 3) Mechanical property tests include tensile test, impact test, KV-T curve test and drop hammer test. The tensile test sampling is circumferential, the sample state includes HTMP state and HTMP+SSRHT state, the test temperature includes room temperature and 350℃, and the tensile strength, yield strength, elongation after fracture and cross-sectional shrinkage of the material should be obtained respectively; the impact test sampling includes circumferential and axial directions, the sample state includes HTMP state and HTMP+SSRHT state, the test temperature includes -20℃, 0℃ and 20℃, and the impact absorption energy and lateral expansion value should be obtained respectively; the KV-T curve test sampling is axial, the sample state includes HTMP state and HTMP+SSRHT state, at least 8 test temperatures should be taken, and a complete KV-T curve and upper platform energy should be obtained; the drop hammer test sampling is circumferential, the sample state is HTMP+SSRHT state, and the reference non-plastic transition temperature should be obtained.

[0075] In this embodiment, the sampling method further includes selecting three generatrixes parallel to the axis of the forging and spaced 120 degrees from each other on the circumferential direction of the inner surface of the cylindrical forging for sampling, cutting multiple samples evenly spaced on the generatrix for chemical composition analysis, and the spacing distance of the multiple samples on the generatrix is ​​200 mm. The sampling distance is limited to ensure the representativeness and accuracy of the forging sampling and avoid the influence of the sampling results on the uneven heat treatment of the forging and the changes in the chemical composition and mechanical properties during the forging process.

[0076] In this embodiment, the sampling method also includes selecting three other busbars parallel to the axis of the forging and spaced 120° from each other on the inner surface of the cylindrical forging to grind a sulfur print inspection belt, the width of the sulfur print inspection belt is 100-150mm, and a sulfur print inspection is performed. Sulfur exists in steel mainly in the form of iron sulfide or manganese sulfide. Iron sulfide forms a eutectic with iron and iron sulfide is often distributed in a network along the grain boundary. This distribution significantly increases the brittleness of steel and may cause hot brittleness. Manganese sulfide has a high melting point, and adding a certain amount of manganese can reduce the hot brittleness of steel. Through the sulfur print inspection, the segregation or distribution of sulfur in steel can be directly inspected, and the distribution of other elements in steel can be indirectly judged, thereby providing an important basis for the quality control and improvement of steel, which is crucial for controlling the quality of steel, avoiding hot brittleness and improving the performance of forgings. The width of the sulfur print inspection belt is 100-150mm. Limiting the width of the sulfur print inspection belt can ensure accurate measurement of sulfur distribution and avoid inspection errors caused by too wide or too narrow inspection areas. Such limitations help improve the accuracy and reliability of inspection, thereby ensuring that the quality of forgings meets standards and requirements.

[0077] The above steps are the preliminary inspection stage. Preliminary inspection is an additional requirement for forging assessment. Inspection at this stage can identify in advance the risks of excessive defects, carbon segregation, excessive impurity elements and other non-conformities in the forging process, which is predictive and necessary in the early stage of manufacturing.

[0078] After sampling and inspection, non-destructive inspection of forgings is also included, specifically: (a) 100% ultrasonic inspection of the processed reactor pressure vessel cylindrical forgings. Ultrasonic inspection includes straight probe inspection and oblique probe inspection. For the core section cylinder, the straight probe inspection results shall meet the quality level I requirements in Table 12 of NB / T 20003.2-2021; for the lower head transition section and the connecting pipe section cylinder, the straight probe inspection results shall meet the quality level II requirements in Table 12 of NB / T 20003.2-2021. During the oblique probe inspection, there should be no defect display with an echo amplitude exceeding 100% of the DAC curve; (b) Magnetic particle inspection is performed on the non-surfacing surface of the processed reactor pressure vessel cylindrical forgings. The surface that needs to be surfacing can be selectively subjected to magnetic particle inspection or liquid penetration inspection.

[0079] Through the above multi-dimensional comprehensive evaluation, a complete and standardized comprehensive technical assessment method is formed.

[0080] Test results

[0081] Table 1 Non-metallic inclusion content (%)

[0082]

[0083]

[0084] According to Table 1, there is no significant difference in the content of non-metallic inclusions in different parts of the cylindrical forgings.

[0085] Table 2 Chemical composition analysis (mass fraction %)

[0086] Test material C Si Mn P S Cr Mo Ni Al Cu Material Ring 1 0.189 0.281 0.744 0.005 0.003 1.65 0.285 1.59 0.037 0.045 Material Ring 2 0.195 0.286 0.743 0.004 0.004 1.62 0.291 1.57 0.038 0.048 Material Ring 3 0.185 0.284 0.738 0.005 0.003 1.66 0.292 1.59 0.037 0.044 Material Ring 4 0.185 0.291 0.735 0.005 0.003 1.62 0.288 1.60 0.036 0.046 Material Ring 5 0.184 0.290 0.734 0.005 0.004 1.64 0.294 1.61 0.037 0.045 Material Ring 6 0.186 0.287 0.741 0.004 0.003 1.65 0.291 1.57 0.037 0.043 Material Ring 7 0.182 0.286 0.744 0.005 0.004 1.66 0.287 1.58 0.036 0.047 Material Ring Eight 0.191 0.285 0.739 0.005 0.004 1.68 0.288 1.58 0.038 0.041 Material Ring Nine 0.192 0.284 0.734 0.005 0.004 1.67 0.292 1.57 0.037 0.043

[0087] Among them, material ring 1 represents the first sample ring, material ring 2 represents the second sample ring, and so on, material ring 9 represents the ninth sample ring. The value is the average value of multiple sample tests for each material ring.

[0088] According to Table 2, there is no obvious difference in the chemical composition of different parts of the cylindrical forgings.

[0089] In addition, the mechanical properties and metallographic test results of the cylindrical forgings show that the test results of various parts of the cylindrical forgings are not much different and are relatively uniform. This shows that the sampling method of the present invention covers the typical area of ​​the cylindrical forgings, and the sampling position is the most representative position in the cylindrical forgings, and the quality of the forgings can be comprehensively and effectively evaluated based on the sample results.

[0090] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for sampling a reactor pressure vessel cylindrical forging, characterized in that: The following steps are involved: S1. Sampling at the nozzle end of the cylindrical forging: S11, first cut the first sample ring, the second sample ring, and the third sample ring in sequence at the position of 1 / 4 wall thickness, 1 / 2 wall thickness, and 3 / 4 wall thickness from the inner surface of the nozzle end, and the thickness of the three sample rings is 40 mm; S12, cutting a plurality of samples in sections along the circumferential direction from the first sample ring, the second sample ring and the third sample ring, wherein the center of each sample ring coincides with the center of the end face of the nozzle end of the forging; S2. Sampling at the riser end of the cylindrical forging: S21. First, cut the fourth test ring, the fifth test ring, and the sixth test ring in sequence at the position of 1 / 4 wall thickness, 1 / 2 wall thickness, and 3 / 4 wall thickness from the inner surface of the riser end. The thickness of the three test rings is 40 mm. The distance between the inner diameter of the fourth test ring and the inner diameter of the forging is 80 mm. The distances between the fourth test ring, the fifth test ring, and the sixth test ring are all 100 mm. S21. Cut a plurality of samples in three layers evenly spaced along the thickness direction of the fourth sample ring, the fifth sample ring and the sixth sample ring, and cut a plurality of samples in each layer along the circumferential direction, and the center of each sample ring coincides with the center of the end face of the riser end of the forging.

2. The method for sampling a reactor pressure vessel cylindrical forging according to claim 1, characterized in that: For the cylindrical forging with an opening, the seventh, eighth and ninth test rings are cut from the opening at the positions of 1 / 4 wall thickness, 1 / 2 wall thickness and 3 / 4 wall thickness from the inner surface for sampling.

3. The method for sampling a reactor pressure vessel cylindrical forging according to claim 2, characterized in that: The seventh sample ring, the eighth sample ring and the ninth sample ring all take at least two samples along the circumferential direction, and the interval between the two samples is 40-80 mm.

4. The method for sampling a reactor pressure vessel cylindrical forging according to any one of claims 1 to 3, characterized in that: The cut specimens are subjected to performance tests under HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile test, at least 18 specimens are used for impact test, at least 24 specimens are used for KV-T curve test, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determination of non-metallic inclusions, and at least 1 specimen is used for determination of grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact test, at least 6 specimens are used for impact test, at least 24 specimens are used for KV-T curve test, at least 8 specimens are used for drop hammer test, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determination of non-metallic inclusions, and at least 1 specimen is used for determination of grain size.

5. The method for sampling a reactor pressure vessel cylindrical forging according to claim 4, characterized in that: The dimensions of the tensile specimen are φ10mm×50mm, the dimensions of the impact specimen are 10mm×10mm×55mm, and the dimensions of the drop weight specimen are 80mm×10mm×4mm.

6. The method for sampling a reactor pressure vessel cylindrical forging according to claim 4, characterized in that: The sample block size for chemical composition analysis and non-metallic inclusions is 25mm×25mm×30mm, and the sample block size for grain size is 25mm×25×30mm.

7. The method for sampling a reactor pressure vessel cylindrical forging according to claim 4, characterized in that: The cylindrical forging comprises a core section cylinder, a lower head transition section and a connecting pipe section cylinder.

8. The method for sampling a reactor pressure vessel cylindrical forging according to claim 7, characterized in that: At least 48 core section cylinder samples are used for KV-T curve test in HTMP state, and at least 12 samples are used for impact test and at least 48 samples are used for KV-T curve test in HTMP+SSRHT state.

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