Quality inspection method of reactor pressure vessel connecting pipe forge piece

Abstract

The invention provides a quality inspection method for a reactor pressure vessel connecting pipe forge piece, and relates to the technical field of manufacturing and production of reactor pressure vessel connecting pipe forge pieces. According to the quality inspection method, samples are cut from different positions of the connecting pipe forge piece to be subjected to a tensile test, an impact test, a KV-T curve test, a drop weight test, a metallographic test, a grain size inspection, non-metallic inclusion determination and chemical component analysis, so that the quality of the reactor pressure vessel connecting pipe forge piece can be comprehensively and effectively evaluated; the rationality and feasibility of the connecting pipe forge piece manufacturing process can be verified according to the connecting pipe forge piece quality.

Description

Technical Field

[0001] The invention relates to the technical field of manufacturing and producing reactor pressure vessel nozzle forgings, in particular to a quality inspection method for reactor pressure vessel nozzle forgings. Background Art

[0002] As the power of reactors continues to increase, the design life of current nuclear power plant pressure vessels is gradually increasing, and higher and higher requirements are placed on the quality of reactor pressure vessels. The pipe forgings in the reactor pressure vessel play a role in ensuring the rigidity of the assembly, bearing the weight of the entire assembly and the impact of the rapid insertion of the control rod. These pipe forgings are welded, and their function is to ensure the rigidity of the assembly, bear the weight of the entire assembly and the impact of the rapid insertion of the control rod, and accurately guide the lifting and lowering of the control rod bundle, ensuring the reliable operation of the assembly in the reactor and the transportation safety during loading and unloading.

[0003] Reactor pressure vessels are the core equipment of nuclear power plants, and their design and manufacturing quality are directly related to the safety and stable operation of nuclear power plants. As a part of the pressure vessel, the quality and performance of nozzle forgings are crucial to ensure the safe operation of nuclear power plants. Therefore, the manufacturing and quality control of nozzle forgings are important links in the design and construction of nuclear power plants.

[0004] The pipe forgings are composed of straight pipes and elbows of different lengths, diameters and wall thicknesses. The pipes also contain many pipe nozzles of different sizes and shapes. These pipe forgings have been changed from casting designs to forging designs, and the elbows, main pipe nozzles and straight pipes are integrally forged. This design greatly improves the service life and reliability of pipe forgings, but it greatly increases the manufacturing difficulty of pipe forgings. In the normal production process of pipe forgings, only samples are taken from the ends of the mother pipe and the pipe nozzle for a small amount of physical and chemical testing, which is far from enough for the process evaluation of pipe forgings and cannot evaluate the manufacturing quality and manufacturing process of pipe forgings.

[0005] Considering the high manufacturing cost of pipe forgings, it is impossible to conduct a comprehensive inspection of each pipe forging in normal production. Therefore, it is necessary to fully consider various manufacturing factors and usage conditions during the quality inspection process and design a method that can comprehensively inspect the quality of pipe forgings while minimizing the inspection cost. Summary of the invention

[0006] The object of the present invention is to provide a quality inspection method for a reactor pressure vessel nozzle forging, which can comprehensively verify the manufacturing quality of the nozzle forging and effectively save costs.

[0007] In the technical assessment of pipe forgings, the sampling position, sampling direction and sampling quantity are the three factors that have the greatest impact on the material performance judgment. Due to various defects and uneven metal structure inside the metal material during the hot and cold deformation process, the deformation amount will not be uniform everywhere, so when sampling at different parts of the product, the mechanical properties test results will inevitably be different.

[0008] Due to the selective crystallization of the pipe forging during the crystallization process, the interface between columnar crystals and equiaxed crystals, the bottom sedimentation cone (negative segregation zone) easily caused by the crystallization zone when the equiaxed crystals are just formed, the shrinkage cavity in the final solidification area and the positive segregation zone with low melting point inclusions nearby, etc., are the main defect concentration areas, all of which are within 40mm below the surface and 1 / 4 of the wall thickness. Therefore, the sampling position should be placed at the position where defects are prone to occur. Only in this way can the qualified sample replace the entire forging and ensure the quality of the pipe forging.

[0009] During the forging process of the pipe forging, as the degree of deformation increases, the coarse dendrites inside the pipe forging gradually elongate along the main deformation direction. At the same time, the direction of the impurities and non-metallic inclusions enriched between the crystals gradually aligns with the main deformation direction, thus forming a streamlined "fibrous structure" along the main deformation direction. During the hot deformation process, due to recrystallization, the elongated grains become fine equiaxed crystals, while the streamlines are stably retained. Such a "fibrous structure" has better mechanical properties along the streamline direction than perpendicular to the streamline direction. Due to the directional differences in the performance of the pipe forging, it is necessary to avoid the areas on the surface of the pipe forging where the structure is dense, defects are less, and the quality is better, which are composed of columnar crystals.

[0010] Based on this, the present invention proposes a quality inspection method for a reactor pressure vessel nozzle forging, comprising the following steps:

[0011] Determine a plurality of test points on the end surface of the extension section of the pipe forging, and cut a plurality of test pieces at each test point;

[0012] Taking the sample point as the starting point, cut a sample line parallel to the axis of the pipe forging along the length direction of the pipe forging, and cut multiple sample pieces on the sample line, with the interval between adjacent sample pieces being 100-200mm;

[0013] The obtained sample pieces are subjected to performance tests, the performance tests including chemical composition analysis, metallographic examination and mechanical property test, the metallographic examination includes non-metallic inclusions and grain size, the mechanical property test includes tensile test, impact test, KV-T curve test and drop hammer test;

[0014] The cut specimens are subjected to performance tests in the HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile tests, at least 18 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact tests, at least 6 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 8 specimens are used for drop hammer tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size.

[0015] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0016] 1) Selecting representative locations for sampling can better reflect the quality of nozzle forgings, fully verify the manufacturing process of the entire nozzle forging, and help to comprehensively and effectively evaluate the various technical indicators of the reactor pressure vessel nozzle forging process assessment stage;

[0017] 2) Due to the directional differences in the forging process of forgings, the sampling position and sampling direction of the sample are reasonably selected. On the one hand, the dense, less defective and better quality area composed of columnar crystals on the forging surface can be avoided, and the sample can be placed in the boundary area between columnar crystals and equiaxed crystals with more defects or in the central equiaxed area; on the other hand, the area with better cooling conditions at the end of the forging can be avoided, so that the sampling has better representativeness;

[0018] 3) Reasonable selection of the sampling quantity of the test sample can avoid the waste of manpower, materials and time caused by excessive sampling, and can also avoid inaccurate judgment of forgings caused by the sampling quantity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of a common nozzle of a reactor pressure vessel;

[0020] Figure 2 It is a cross-sectional view of a common nozzle of a reactor pressure vessel;

[0021] Figure 3 It is a structural schematic diagram of an L-shaped nozzle of a reactor pressure vessel;

[0022] Figure 4 It is a cross-sectional view of the L-shaped nozzle of the reactor pressure vessel. DETAILED DESCRIPTION

[0023] 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.

[0024] First, this embodiment provides a method for quality inspection of a reactor pressure vessel nozzle forging, wherein the nozzle forging includes a common nozzle and an L-shaped nozzle, and includes the following steps:

[0025] Determine a plurality of test points on the end surface of the extension section of the pipe forging, and cut a plurality of test pieces at each test point;

[0026] Taking the sample point as the starting point, cut a sample line parallel to the axis of the pipe forging along the length direction of the pipe forging, and cut multiple sample pieces on the sample line, with the interval between adjacent sample pieces being 100-200mm;

[0027] The obtained sample pieces are subjected to performance tests, the performance tests including chemical composition analysis, metallographic examination and mechanical property test, the metallographic examination includes non-metallic inclusions and grain size, the mechanical property test includes tensile test, impact test, KV-T curve test and drop hammer test;

[0028] The cut specimens are subjected to performance tests in the HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile tests, at least 18 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact tests, at least 6 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 8 specimens are used for drop hammer tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size.

[0029] By limiting the sampling position and direction, on the one hand, the dense, less defective and better quality area composed of columnar crystals of steel ingot can be avoided, and the sample can be placed in the boundary area between columnar crystals and equiaxed crystals with more defects or in the central equiaxed area; on the other hand, the area with better cooling conditions at the end of the forging can be avoided, making the sampling more representative.

[0030] When inspecting forgings, the number of samples is also critical to the judgment of product quality. If the number of samples is small, the representativeness of the inspection results is poor, but if the number of samples is large, it will cause a waste of manpower, materials and time. In order to determine the minimum sampling number, it is necessary to conduct a specific analysis of specific issues based on the type of experiment, the purpose of product and material performance, the dispersion of experimental results and economic factors. The present invention can effectively overcome the problem of inaccurate forging quality assessment caused by poor sampling quantity by limiting the number of test pieces.

[0031] Furthermore, the pipe forging includes a common pipe and an L-shaped pipe.

[0032] Furthermore, when sampling the common pipe forging, it also includes cutting the sample in three layers along the thickness direction of the common pipe at the position of the maximum diameter of the common pipe, the first layer is 40mm away from the inner wall surface, the second layer is 1 / 2 of the wall thickness, and the third layer is 40mm away from the outer wall surface. Since the diameter of the pipe changes, the transition zone of the diameter change will affect the stress distribution, causing the stress to be concentrated at the position of the maximum diameter, resulting in local high stress, which is the place where more defects are generated. The present invention can more comprehensively reflect the quality of the forgings by sampling at the position of the maximum diameter, and improve the accuracy of the evaluation of the forging manufacturing process technology.

[0033] Furthermore, when sampling the L-shaped pipe forging, it also includes cutting samples at the inner corner position and the outer corner position of the L-shaped pipe forging. Specifically: the L-shaped pipe is cut along the axis, and sampling is performed on and / or inside the rectangle formed by the position 40-80mm in the height and width direction of the center position of the corner cross section. The stress of the L-shaped pipe is concentrated at the corner, and the internal pressure and external load will cause complex stress distribution inside the pipe, including axial stress, bending stress, radial stress, etc. The present invention forms a rectangle of a certain size in the corner cross section, and then samples on and / or inside the rectangle. The obtained sample is not only representative, but also meets the uniformity of sampling, and can fully and comprehensively reflect the overall quality of the forging.

[0034] Furthermore, in common pipe forgings, the sample points include two positions 180° apart, 40 mm from the outer surface, 40 mm from the inner surface, and 1 / 2 of the wall thickness of the pipe forging extension section.

[0035] Furthermore, in the L-shaped pipe forging, the sample points include the positions of 1 / 4 wall thickness, 1 / 2 wall thickness and 3 / 4 wall thickness of the extended section of the pipe forging from the inner surface.

[0036] Furthermore, it also includes selecting three busbars on the circumferential direction of the inner surface of the forging that are parallel to the axis of the forging and spaced 120° from each other for sampling and chemical composition analysis; selecting another three busbars on the circumferential direction of the inner surface of the forging that are parallel to the axis of the forging and spaced 120° from each other and grinding the sulfur print inspection tape for sulfur print inspection.

[0037] In this embodiment, the spacing of multiple samples on the busbar is 200 mm. The sampling distance is limited to ensure the representativeness and accuracy of forging sampling and avoid the influence of the sampling results due to the uneven heat treatment of the forging and the changes in chemical composition and mechanical properties during the forging process.

[0038] In this embodiment, the width of the sulfur print inspection belt is 100-150 mm. Limiting the width of the sulfur print inspection belt can ensure accurate measurement of sulfur distribution and avoid inspection errors caused by inspection areas that are too wide or too narrow. Such a limitation helps to improve the accuracy and reliability of the inspection, thereby ensuring that the quality of the forgings meets the standards and requirements. Preferably, it is 130 mm.

[0039] Among them, busbar sampling and sulfur print inspection are the preliminary inspection stage. Preliminary inspection is an additional requirement for forging assessment. The 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.

[0040] 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 pipe forgings, the P content should be controlled below 0.008%, the S content should be controlled below 0.005%, and the Cu content should be controlled below 0.08%;

[0041] 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 / T 223 may also be used. If there is a dispute over the test results of a certain element, the test results of GB / T 223 shall prevail.

[0042] The tensile test sampling is circumferential, the sample states include 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 states include 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 states include 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.

[0043] After sampling and inspection, non-destructive inspection of forgings is also included, specifically: (a) 100% ultrasonic inspection of the processed reactor pressure vessel nozzle forgings. Ultrasonic inspection includes straight probe inspection and oblique probe inspection. The straight probe inspection results should meet the requirements of quality level II in Table 12 of NB / T 20003.2-2021. During oblique probe inspection, there should be no defect display with 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 nozzle forgings. The surface that needs to be surfacing can be selectively subjected to magnetic particle inspection or liquid penetration inspection.

[0044] For low alloy steel nozzle forgings of reactor pressure vessels, the most commonly used process flow is:

[0045] Smelting - forging - post-forging heat treatment - rough machining - performance heat treatment - finishing. The quality inspection method of this embodiment is applicable to the above process. Taking the ordinary pipe of the Hualong No. 1 reactor pressure vessel as an example, its specific implementation method is as follows:

[0046] (1) Smelting stage

[0047] 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 170 tons. Among them, the method of rough refining in electric furnace (EF) + vacuum refining and vacuum pouring process are the key processes for evaluation; the number of 3 bags of molten steel for co-casting is the key parameter for evaluation, and the weight of the steel ingot is 170 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, and the chemical composition shall be carried out in accordance with the relevant provisions of GB / T223.

[0048] (2) Forging stage

[0049] The forging process and forging sequence of common pipe forgings are as follows:

[0050] Gas cutting of nozzles, risers and ingot body discarded - upsetting - punching - drawing - gas cutting of blanks - pipe production to produce finished forgings.

[0051] 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. The amount of steel ingot removed should be sufficient, and the weight of the steel ingot and the percentage of removed weight should be recorded and archived. The head and tail removal amount of the forging are key parameters for evaluation, and the total forging ratio of the forging should be greater than 3, which is the key parameter for evaluation.

[0052] (3) Post-forging heat treatment stage

[0053] 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.

[0054] (4) Rough processing stage

[0055] The overall dimensions of the rough-machined forgings should be as close as possible to those of the final product, but sufficient dimensions 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.

[0056] (5) Performance heat treatment stage

[0057] 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).

[0058] 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℃.

[0059] Based on the above-mentioned quality inspection method for reactor pressure vessel nozzle forgings, an evaluation method for reactor pressure vessel nozzle forgings is provided. Combined with the manufacturing process of nozzle forgings, the key evaluation processes and key evaluation parameters of the evaluation method are summarized as follows:

[0060] Smelting: smelting process, number of ladles, weight of ingots.

[0061] Forging: forging process, forging sequence, head / tail removal, total forging ratio.

[0062] Post-forging heat treatment: post-forging heat treatment process, number of heat treatments, normalizing temperature, tempering temperature, and holding time.

[0063] Performance heat treatment: performance heat treatment process, number of heat treatments, quenching temperature, tempering temperature, holding time, heating rate, cooling rate.

[0064] Sampling inspection: sample status, sampling location, and sampling quantity.

[0065] Non-destructive testing: acceptance criteria.

[0066] 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.

[0067] Through the above multi-dimensional comprehensive evaluation, a complete and standardized comprehensive evaluation method for nozzle forgings is formed.

[0068] Example 1

[0069] A quality inspection method for a reactor pressure vessel nozzle forging, taking a common nozzle forging as an example, comprises the following steps:

[0070] Determine a plurality of test points on the end surface of the extension section of the pipe forging, and cut a plurality of test pieces at each test point;

[0071] Taking the sample point as the starting point, cut a sample line parallel to the axis of the pipe forging along the length direction of the pipe forging, and cut multiple sample pieces on the sample line, with the interval between adjacent sample pieces being 100 mm;

[0072] The samples were cut into three layers along the thickness direction of the common pipe at the position with the maximum diameter. The first layer was 40 mm away from the inner wall, the second layer was at 1 / 2 of the wall thickness, and the third layer was 40 mm away from the outer wall.

[0073] The obtained sample pieces are subjected to performance testing, and the performance tests include chemical composition analysis, metallographic examination and mechanical property test. The metallographic examination includes non-metallic inclusions and grain size, and the mechanical property test includes tensile test, impact test, KV-T curve test and drop hammer test.

[0074] The cut specimens are subjected to performance tests in the HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile tests, at least 18 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact tests, at least 6 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 8 specimens are used for drop hammer tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size.

[0075] The test points include two positions at 40 mm from the outer surface, 40 mm from the inner surface and 180° apart at 1 / 2 of the wall thickness of the extended section of the pipe forging.

[0076] Example 2

[0077] A quality inspection method for a reactor pressure vessel nozzle forging, taking an L-shaped nozzle forging as an example, comprises the following steps:

[0078] Determine a plurality of test points on the end surface of the extension section of the pipe forging, and cut a plurality of test pieces at each test point;

[0079] Taking the sample point as the starting point, cut a sample line parallel to the axis of the pipe forging along the length direction of the pipe forging, and cut multiple sample pieces on the sample line, with the interval between adjacent sample pieces being 200 mm;

[0080] The L-shaped pipe is cut open along the axis, and samples are taken on and within the rectangle formed by the 60 mm position in the height and width directions of the center position of the corner cross section.

[0081] The obtained sample pieces are subjected to performance testing, and the performance tests include chemical composition analysis, metallographic examination and mechanical property test. The metallographic examination includes non-metallic inclusions and grain size, and the mechanical property test includes tensile test, impact test, KV-T curve test and drop hammer test.

[0082] The cut specimens are subjected to performance tests in the HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile tests, at least 18 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact tests, at least 6 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 8 specimens are used for drop hammer tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size.

[0083] The sampling points include the position of 1 / 4 wall thickness, 1 / 2 wall thickness and 3 / 4 wall thickness of the extended section of the pipe forging from the inner surface.

[0084] Test results

[0085] Table 1 Impact performance test results

[0086]

[0087]

[0088] Table 2 Non-metallic inclusion content (%)

[0089]

[0090]

[0091] According to Table 1 and Table 2, the fluctuation of values ​​between different parts of the pipe forging is small and relatively uniform, which indicates that the quality of the pipe forging is good and the forging process of the pipe forging meets the assessment requirements.

[0092] In summary, the sampling position and sampling quantity of the present invention can effectively test the quality of the pipe forging, help to evaluate the manufacturing process of the pipe forging, and verify the rationality and feasibility of the manufacturing process of the pipe forging.

[0093] 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 quality inspection of reactor pressure vessel nozzle forgings, characterized in that: The following steps are involved: Determine a plurality of test points on the end surface of the extension section of the pipe forging, and cut a plurality of test pieces at each test point; Taking the sample point as the starting point, cut a sample line parallel to the axis of the pipe forging along the length direction of the pipe forging, and cut multiple sample pieces on the sample line, with the interval between adjacent sample pieces being 100-200mm; The obtained sample pieces are subjected to performance tests, the performance tests including chemical composition analysis, metallographic examination and mechanical property test, the metallographic examination includes non-metallic inclusions and grain size, the mechanical property test includes tensile test, impact test, KV-T curve test and drop hammer test; The cut specimens are subjected to performance tests in the HTMP state and HTMP+SSRHT. In the HTMP state, at least 2 specimens are used for tensile tests, at least 18 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size; in the HTMP+SSRHT state, at least 2 specimens are used for impact tests, at least 6 specimens are used for impact tests, at least 24 specimens are used for KV-T curve tests, at least 8 specimens are used for drop hammer tests, at least 1 specimen is used for chemical composition analysis, at least 1 specimen is used for determining non-metallic inclusions, and at least 1 specimen is used for determining grain size.

2. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 1, characterized in that: The pipe forgings include ordinary pipes and L-shaped pipes.

3. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 2, characterized in that: When sampling ordinary pipe forgings, it also includes cutting samples in three layers along the thickness direction of the ordinary pipe at the position of the maximum diameter of the ordinary pipe. The first layer is 40mm away from the inner wall, the second layer is 1 / 2 of the wall thickness, and the third layer is 40mm away from the outer wall.

4. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 2, characterized in that: When sampling the L-shaped pipe forging, it also includes cutting samples at the inner corner and outer corner of the L-shaped pipe forging.

5. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 4, characterized in that: The L-shaped pipe forging is cut open along the axis, and sampling is performed on and / or within a rectangle formed by a position 40-80 mm in height and width directions at the center of the corner cross section.

6. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 2, characterized in that: In common pipe forgings, the sample points include two positions 180° apart at 40 mm from the outer surface, 40 mm from the inner surface and 1 / 2 of the wall thickness of the pipe forging extension section.

7. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 2, characterized in that: In the L-shaped pipe forging, the sample points include the position of 1 / 4 wall thickness, 1 / 2 wall thickness and 3 / 4 wall thickness of the extended section of the pipe forging from the inner surface.

8. The quality inspection method for reactor pressure vessel nozzle forgings according to claim 1, characterized in that: It also includes selecting three busbars on the circumferential direction of the inner surface of the forging that are parallel to the axis of the forging and spaced 120° from each other for sampling and chemical composition analysis; selecting another three busbars on the circumferential direction of the inner surface of the forging that are parallel to the axis of the forging and spaced 120° from each other and grinding the sulfur print inspection tape for sulfur print inspection.

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