A method for manufacturing a high-purity and high-homogeneity nuclear power pressure vessel

Abstract

The present application belongs to the field of forging, and particularly relates to a manufacturing method of a high-purity and high-homogenization nuclear power pressure vessel. First, the continuous casting slab is screened through the chemical composition segregation amount, and the high-homogenization continuous casting slab is screened as a building block; then the length, width or diameter of the homogenization building block is processed in equal size, and after cleaning treatment, multiple building blocks are stacked, and the stacked multiple homogenization building blocks are vacuum packaged to form a building blank, and after packaging, the building blank is removed from the vacuum chamber and placed into a heating furnace to be heated to a forging temperature for building forming forging; finally, the high-purity and high-homogenization nuclear power pressure vessel is manufactured through forging or ring rolling. The cylinder forging produced by the method not only has good composition homogeneity, but also has good uniformity of mechanical properties, greatly improving the comprehensive performance of the cylinder forging, and providing a new method for high-purity and high-homogenization manufacturing of nuclear power pressure vessel forgings.

Description

Technical Field

[0001] This invention belongs to the field of forging, and specifically relates to a method for manufacturing a high-purity, high-homogeneity nuclear power vessel. Background Technology

[0002] Currently, the nuclear power plants operating in China are mainly pressurized water reactor nuclear power plants. Some large forgings such as nuclear power pressure vessels in nuclear power plants are produced by forging large steel ingots. However, this process also has a major problem: predicting the segregation composition of the steel ingot. Often, the forging is only "two parts made, one part guaranteed." The large steel ingot has serious chemical composition segregation, coarse grains, and excessive non-metallic inclusions. The forgings produced often fail to meet performance standards due to the inhomogeneity of the material itself. This problem seriously affects the manufacturing cycle and stability of the forgings.

[0003] Metal construction forming technology is a novel processing and manufacturing technology that Chinese researchers pioneered internationally, enabling large-scale production from small components. It breaks through the traditional subtractive manufacturing paradigm that base materials for metal components can only be larger than the original material. Multiple homogeneous slabs are surface-processed, cleaned, assembled, and vacuum-sealed. Then, a hot deformation joining process involving deformation joining and multi-directional forging is applied at high temperatures to fully heal the interfaces, achieving a seamless connection between the interface and the substrate, thus obtaining large-sized homogeneous billets.

[0004] Traditionally, nuclear power pressure vessels manufactured using steel ingots cannot achieve strict control over the chemical composition segregation of the forgings. The building blocks used in metal fabrication forming technology are typically continuously cast slabs. For the fabrication of high-purity, highly homogeneous nuclear power pressure vessels, strict control over the homogenization and purification of the continuously cast slabs is necessary. Therefore, if new technologies can be used to strictly control the quality of the continuously cast slabs before fabrication, the risk of manufacturing failure can be avoided, and the manufacturing challenge of high-purity, highly homogeneous nuclear power pressure vessel forgings can be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel, which solves the problem of homogenization preparation of nuclear power pressure vessel forgings.

[0006] The technical solution of this invention is:

[0007] A method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel includes the following steps:

[0008] The first step is to test the chemical composition of different locations of the same batch of continuous casting billets and select the continuous casting billets with similar chemical compositions as building blocks.

[0009] The second step is to process the building blocks to the same dimensions (length, width, or diameter) and then clean their surfaces.

[0010] The third step is to stack the cleaned homogenized building blocks.

[0011] The fourth step is to place the stacked building blocks into a vacuum chamber for vacuum sealing;

[0012] The fifth step is to heat and forge the packaged billet to form an integral blank;

[0013] The sixth step is to shape the blank to the final required size.

[0014] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, in the first step, when testing the chemical composition of the continuous casting billet, the same batch of continuous casting billets includes at least a head billet and a tail billet, and the sampling location includes at least 1 / 2 of the width of the upper (or lower) surface of the continuous casting billet, the geometric center of the cross-section, and 1 / 2 of the thickness of the side surface; for different batches of continuous casting billets, the head billet and the tail billet of each batch of continuous casting billets are tested separately.

[0015] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, in the first step, the carbon segregation at different positions of the selected continuous casting billet from the same furnace is less than 15%, and the carbon segregation at different furnace batches of continuous casting billets is less than 20%.

[0016] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, in the first step, a test block is cut from the continuous casting billet that meets the chemical composition requirements and forged. The content of non-metallic inclusions in the forged continuous casting billet is then tested, and the continuous casting billet that meets the technical conditions for non-metallic inclusions in the final forging is selected as the building block.

[0017] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, in the first step, the test block is cut at the middle position of the width of the head or tail of the continuous casting billet, and the length and width of the test block are greater than or equal to the thickness of the continuous casting billet.

[0018] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, the forging ratio is ≥3.0 in the first step.

[0019] In the third step of the manufacturing method for the high-purity, high-homogeneity nuclear power pressure vessel, continuous casting billets with large chemical composition deviations from different furnace numbers are stacked crosswise to make the overall billet uniform after stacking.

[0020] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, in the third step, after stacking, the misalignment of two adjacent slabs after alignment is less than 2mm, and the gap is less than 1mm; preferably, after stacking, the misalignment of two adjacent slabs after alignment is less than 1mm, and the gap is less than 0.5mm.

[0021] In the fifth step of the manufacturing method for the high-purity, high-homogeneity nuclear power pressure vessel, the heating temperature is 0.8–0.9T. m T mThe value is the melting point of the material, expressed in °C. The reduction for forging the billet is 10% to 60%.

[0022] In the manufacturing method of the high-purity, high-homogeneity nuclear power pressure vessel, in the sixth step, when manufacturing the nuclear power pressure vessel cylinder, it is rolled into a cylinder forging by rounding, punching, expanding, or expanding and then rolling.

[0023] The design concept of this invention is:

[0024] First, the building blocks to be constructed are screened through chemical composition analysis and inclusion content analysis to ensure that the composition of the building blocks used is uniform and the composition deviation is small. Then, the building blocks with large chemical composition deviations are stacked evenly at intervals during the stacking process, and the composition is further homogenized by subsequent heating and forging, thereby reducing the composition segregation of the billet after construction and realizing the high purity and high homogeneity manufacturing of nuclear power pressure vessel forgings.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0026] Existing metal forming technologies directly use continuously cast slabs as building blocks, making it impossible to precisely control the chemical composition segregation and inclusion content of forgings. The cylindrical forgings produced using the process method of this invention, through control of the chemical composition and inclusions of the continuously cast slab, can effectively ensure the purity and homogeneity of the building blocks, keeping the carbon segregation of the forgings below 20% and all types of inclusions below grade 1.0. Furthermore, by uniformly stacking building blocks with large chemical composition deviations during the stacking process, the overall chemical composition homogeneity is further increased, thereby achieving high-purity and high-homogeneity manufacturing of nuclear power pressure vessel forgings. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the sampling locations for the chemical composition of a continuously cast billet cross-section. The numbers in the diagram are explained as follows: 1 - 1 / 2 of the width of the upper (or lower) surface of the continuously cast billet; 2 - 1 / 4 of the thickness of the center of the width of the continuously cast billet; 3 - the geometric center of the cross-section; 4 - 1 / 4 of the width and thickness of the continuously cast billet at its center; 5 - 1 / 2 of the thickness of the side surface.

[0028] Figure 2 This is a schematic diagram of three surfaces in multi-directional forging.

[0029] Figure 3 This is a schematic diagram of the stacking of 15 layers of continuously cast billets in two furnaces.

[0030] Figure 4 This is a schematic diagram of the stacking of 12 layers of continuously cast billets in three furnaces. Detailed Implementation

[0031] In its specific implementation, this invention provides a method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel. First, the chemical composition of different locations on the continuously cast slab is analyzed and screened to select highly homogeneous continuously cast slabs with lower chemical segregation as building blocks. Then, adjacent planes of the homogeneous building blocks are machined to the same dimensions. After cleaning, two or more building blocks are stacked. These stacked homogeneous building blocks are then vacuum-sealed to form a building billet. After welding, the building billet is placed in a heating furnace and heated to forging temperature for forging. Finally, the high-purity, high-homogeneity nuclear power pressure vessel is manufactured by forging or ring rolling. The specific steps of this method are as follows:

[0032] The first step is to perform chemical composition analysis on different locations within the same batch of continuously cast billets, selecting those with similar chemical compositions as building blocks. When analyzing the chemical composition of continuously cast billets, the same furnace should include at least the head and tail billets. Sampling locations are as follows: Figure 1 As shown, the sampling area should at least include half the width of the upper (or lower) surface of the continuously cast billet, the geometric center of the cross-section, and half the thickness of the side surface. Billets from different heats should be tested separately for each heat. The carbon segregation at different locations on the selected billets from the same heat should be less than 15%, and the carbon segregation at all sampling locations on billets from different heats should be less than 20%. The calculation method for carbon segregation is as follows:

[0033] C segregation = (highest C content at the selected component point - lowest C content at the selected component point) / lowest C content at the selected component point × 100%

[0034] The second step involves forging a small sample block from the continuously cast billet that meets the chemical composition requirements, and then testing the non-metallic inclusion content of the forged billet. First, a sample block with dimensions greater than or equal to the thickness of the continuously cast billet is cut from the middle of the width of the head or tail of the billet. This sample block is then subjected to multi-directional forging with a forging ratio of not less than 3.0 (preferably 3-6). The sample block is then tested for non-metallic inclusions, and the continuously cast billet that meets the technical requirements for non-metallic inclusions in the final forging is selected as the building block.

[0035] The third step is to process the building blocks to the same dimensions (length, width, or diameter) and then clean their surfaces. Adjacent building blocks are processed to the same dimensions (length, width, or diameter), and the top and bottom surfaces are made flat. The processed building blocks are then cleaned using methods such as machining, grinding, cleaning fluid cleaning, laser cleaning, or electropolishing.

[0036] The fourth step involves stacking the cleaned, homogenized building blocks. Continuous casting billets with significant chemical composition variations from different furnace numbers are stacked crosswise to ensure overall uniformity of the stacked building blocks. During stacking, the upper and lower surfaces of adjacent building blocks are aligned. After alignment, the misalignment should be less than 2 mm, and the gap less than 1 mm. Preferably, the misalignment should be less than 1 mm, and the gap less than 0.5 mm.

[0037] The fifth step involves placing the stacked building blocks into a vacuum chamber for vacuum sealing: The stacked building blocks are placed in the vacuum chamber and evacuated, creating a vacuum between adjacent building blocks. Welding is then performed along the contact seams of each billet, with the weld seam surrounding the entire billet, thus achieving vacuum sealing between adjacent building blocks. This ensures that the vacuum state between the building blocks is maintained even after they exit the vacuum chamber. Once all interfaces between the building blocks are sealed, a building blank is obtained.

[0038] The sixth step is to perform heated forging on the packaged billet: the billet is sent to a heating furnace for heating at a temperature of 0.8–0.9T. m T m is the melting point of the material, in °C. After heating, the billet is deformed perpendicular to the interface between the building elements, with a reduction of 10% to 60%, resulting in a blank.

[0039] The seventh step is to shape the blank to the final required dimensions. When manufacturing the cylinder of a nuclear power pressure vessel, it is rolled into a cylinder forging through processes such as rounding, punching, reaming, or reaming followed by rolling.

[0040] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The drawings, which constitute a part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0041] Example 1

[0042] In this embodiment, SA-508Gr.3Cl2 (carbon content approximately 0.22wt%) continuous casting billets with a width × thickness of 2200mm × 250mm produced in two furnaces were used for the construction and forming of the nuclear power pressure vessel cylinder forging. The continuous casting billets were subjected to chemical composition and non-metallic inclusion testing. Billets with similar chemical compositions were selected as building blocks. After surface cleaning and stacking, they underwent vacuum electron beam encapsulation, construction forging, and rolling. The specific steps are as follows:

[0043] First step, such as Figure 1As shown, 30mm thick test blocks were cut from the first and last billets of the two furnaces. Samples were taken from five different locations on the test blocks: 1) at half the width of the upper surface, 2) at the center of the width and 1 / 4 of the thickness, 3) at the geometric center of the cross-section, 4) at the center of the 1 / 4 width and thickness, and 5) at half the thickness of one side surface. The carbon content of the same continuous casting billet at different locations was selected as the building blocks, with carbon content of 0.22–0.24 wt% and 0.23–0.25 wt% (carbon segregation less than 10%), and the carbon content of different furnace batches was selected as 0.22–0.25 wt% (segregation less than 15%).

[0044] The second step involved taking a 250mm × 250mm × 500mm sample from the end of each of the two batches of continuously cast billets that met the chemical composition requirements. This sample was then subjected to multi-directional forging at a forging ratio of 4.0, and the non-metallic inclusion content of the forged billets was measured. The results showed that both batches contained 0.5 grade A, B, and C type inclusions and 1.0 grade D type coarse inclusions, meeting the technical requirements. Therefore, a high-purity, highly homogeneous continuously cast billet was selected as the building block.

[0045] In this embodiment, multi-directional forging specifically refers to: Figure 2 As shown, upsetting forging was performed on surfaces A, B, and C of the test block, respectively.

[0046] The third step is to process the building blocks to the same dimensions and perform surface cleaning. The two batches of building blocks are sawn into 2000mm×2200mm equal-sized blanks, with 8 blanks in the first batch and 7 blanks in the second batch, for a total of 15 blanks. The oxide layer on the upper and lower surfaces of the blanks is removed and the surfaces are machined flat. The upper and lower surfaces of the processed building blocks are then mechanically polished and cleaned with alcohol.

[0047] Step four, as Figure 3 As shown, the 15 homogenized building blocks after cleaning are stacked. The billets from two continuous casting furnaces are stacked crosswise, with number 1 representing the building block from the first furnace and number 2 representing the building block from the second furnace. This ensures the stacked building blocks are uniform in size, and the upper and lower surfaces of adjacent building blocks are aligned during stacking. A schematic diagram of the stacking is shown below. Figure 3 After alignment, the misalignment should be less than 2mm, and the gap should be less than 1mm.

[0048] The fifth step involves placing the stacked building blocks into a vacuum chamber for vacuum sealing: The stacked building blocks are placed in the vacuum chamber and evacuated, creating a vacuum between adjacent building blocks. Welding is then performed along the contact seams of each billet, with the weld seam surrounding the entire billet, thus achieving vacuum sealing between adjacent building blocks. This ensures that the vacuum state between the building blocks is maintained even after they exit the vacuum chamber. Once all interfaces between the building blocks are sealed, a building blank is obtained.

[0049] The sixth step is to perform heated forging on the packaged billet: the billet is sent to a heating furnace for heating at a temperature of 0.8–0.9T. m T m is the melting point of the material, in °C. After heating, the billet is deformed perpendicular to the interface between the building elements, with a reduction of 50%, resulting in a blank.

[0050] The seventh step involves rolling, punching, expanding, and rolling the blank into a nuclear power pressure vessel cylinder forging with a diameter of 5 meters, a height of 3 meters, and a wall thickness of 250 mm, thus completing the manufacturing of a high-purity, high-homogeneity nuclear power pressure vessel cylinder forging.

[0051] Example 2

[0052] In this embodiment, SA-508Gr.3Cl1 (carbon content approximately 0.18wt%) continuous casting billets with a width × thickness of 1500mm × 200mm produced by three furnaces were used for the construction and forming of the nuclear power pressure vessel cylinder forging. The continuous casting billets were subjected to chemical composition and non-metallic inclusion testing. Billets with similar chemical compositions were selected as building blocks. After surface cleaning and stacking, they underwent vacuum electron beam encapsulation, construction forging, and rolling. The specific steps are as follows:

[0053] First step, such as Figure 1 As shown, 30mm thick test blocks were cut from the first and last billets of the three furnaces. Samples were taken from five different locations on the test blocks: 1) at half the width of the upper surface, 2) at the center of the width and 1 / 4 of the thickness, 3) at the geometric center of the cross-section, 4) at the center of the 1 / 4 width and thickness, and 5) at half the thickness of one side surface. Chemical composition analysis was performed on these samples. Continuous casting billets with carbon contents of 0.16–0.18 wt%, 0.16–0.17 wt%, and 0.17–0.19 wt% (all with carbon segregation less than 15%) at different locations within the same continuous casting billet, and with carbon contents of 0.16–0.19 wt% (segregation less than 20%) across different furnace batches, were selected as building blocks.

[0054] The second step involved cutting a 200mm × 200mm × 300mm sample from the end of each of the three continuously cast billets that met the chemical composition requirements. This sample was then subjected to multi-directional forging at a forging ratio of 5.0, and the non-metallic inclusion content of the forged billets was measured. The results showed that the non-metallic inclusion content in all three batches was 0.5 grade for A, B, and C type inclusions, and 1.0 grade for D type coarse inclusions, meeting the technical requirements. Therefore, a high-purity, highly homogeneous continuously cast billet was selected as the building block.

[0055] In this embodiment, multi-directional forging specifically refers to: Figure 2 As shown, the A, B and C surfaces of the test block were upsetting and then rolled into round shape.

[0056] The third step involves machining the building blocks to the same dimensions and cleaning their surfaces. The three furnace building blocks are sawn into 1500mm x 1500mm blanks, with 4 blanks for the first furnace, 4 blanks for the second furnace, and 4 blanks for the third furnace, for a total of 12 blanks. The oxide layer on the top and bottom surfaces of the blanks is removed and the surfaces are machined flat. The top and bottom surfaces of the machined building blocks are then mechanically polished and cleaned with alcohol.

[0057] Step four, as Figure 4 As shown, the 12 homogenized building blocks after cleaning are stacked. The three continuous casting billets are stacked crosswise, with number 1 representing the building block of the first furnace, number 2 representing the building block of the second furnace, and number 3 representing the building block of the third furnace. This ensures that the stacked building blocks are uniform in size, and the upper and lower surfaces of adjacent building blocks are aligned during stacking. See the stacking diagram below. Figure 4 After alignment, the misalignment should be less than 2mm, and the gap should be less than 1mm.

[0058] The fifth step involves placing the stacked building blocks into a vacuum chamber for vacuum sealing: The stacked building blocks are placed in the vacuum chamber and evacuated, creating a vacuum between adjacent building blocks. Welding is then performed along the contact seams of each billet, with the weld seam surrounding the entire billet, thus achieving vacuum sealing between adjacent building blocks. This ensures that the vacuum state between the building blocks is maintained even after they exit the vacuum chamber. Once all interfaces between the building blocks are sealed, a building blank is obtained.

[0059] The sixth step is to perform heated forging on the packaged billet: the billet is sent to a heating furnace for heating at a temperature of 0.8–0.9T. m T m is the melting point of the material, in °C. After heating, the billet is deformed perpendicular to the interface between the building elements, with a reduction of 50%, resulting in a blank.

[0060] The seventh step involves rolling, punching, expanding, and rolling the blank into a nuclear power pressure vessel cylinder forging with a diameter of 4.5 meters, a height of 2 meters, and a wall thickness of 220 mm, thus completing the manufacturing of a high-purity, high-homogeneity nuclear power pressure vessel cylinder forging.

[0061] Example 3

[0062] In this embodiment, SA-508Gr.3Cl2 (carbon content approximately 0.22wt%) continuous casting billets with a width × thickness of 2200mm × 300mm produced by three furnaces were used to construct the water chamber head forging of the nuclear power pressure vessel. The continuous casting billets were tested for chemical composition and non-metallic inclusions. Billets with similar chemical compositions were selected as building blocks. After surface cleaning and stacking, they were vacuum electron beam encapsulated, constructed, forged, and rolled. The specific steps are as follows:

[0063] First step, such as Figure 1 As shown, 30mm thick test blocks were cut from the first and last billets of the three furnaces. Samples were taken from five different locations on the test blocks: 1) at half the width of the upper surface, 2) at the center of the width and 1 / 4 of the thickness, 3) at the geometric center of the cross-section, 4) at the center of the 1 / 4 width and thickness, and 5) at half the thickness of one side surface. The carbon content of the same continuous casting billet at different locations was selected as the building blocks, with carbon content of 0.21–0.24 wt%, 0.22–0.25 wt%, and 0.23–0.25 wt% (all with carbon segregation less than 15%), and the carbon content of different furnace batches was selected as 0.21–0.25 wt% (segregation less than 20%).

[0064] The second step involved cutting a 250mm × 250mm × 600mm sample from the end of each of the three continuously cast billets that met the chemical composition requirements. This sample was then subjected to multi-directional forging at a forging ratio of 6.0, and the non-metallic inclusion content of the forged billets was measured. The results showed that the non-metallic inclusion content in all three batches was 0.5 grade for A, B, and C type inclusions and 1.0 grade for D type coarse inclusions, meeting the technical requirements. Therefore, a high-purity, highly homogeneous continuously cast billet was selected as the building block.

[0065] In this embodiment, multi-directional forging specifically refers to: Figure 2 As shown, upsetting forging was performed on surfaces A, B, and C of the test block, respectively.

[0066] The third step involves machining the building blocks to the same dimensions and then cleaning their surfaces. The three furnaces of building blocks are sawn into 2200mm x 2200mm blanks, with 6 blanks for the first furnace, 5 for the second, and 5 for the third, totaling 16 blanks. The oxide layer on the top and bottom surfaces of the blanks is removed and smoothed. The processed building blocks are then mechanically polished and cleaned with alcohol.

[0067] The fourth step involves stacking the 16 homogenized building blocks after cleaning. The three continuous casting billets are stacked crosswise, with number 1 representing the building block from the first furnace, number 2 from the second furnace, and number 3 from the third furnace. This ensures the stacked building blocks are uniform in size, and the upper and lower surfaces of adjacent building blocks are aligned during stacking. After alignment, the misalignment should be less than 2mm, and the gap less than 1mm.

[0068] The fifth step involves placing the stacked building blocks into a vacuum chamber for vacuum sealing: The stacked building blocks are placed in the vacuum chamber and evacuated, creating a vacuum between adjacent building blocks. Welding is then performed along the contact seams of each billet, with the weld seam surrounding the entire billet, thus achieving vacuum sealing between adjacent building blocks. This ensures that the vacuum state between the building blocks is maintained even after they exit the vacuum chamber. Once all interfaces between the building blocks are sealed, a building blank is obtained.

[0069] The sixth step is to perform heated forging on the packaged billet: the billet is sent to a heating furnace for heating at a temperature of 0.8–0.9T. m T m is the melting point of the material, in °C. After heating, the billet is deformed perpendicular to the interface between the building elements, with a reduction of 50%, resulting in a blank.

[0070] The seventh step involves rolling, drawing, and forging the blank into a nuclear power pressure vessel water chamber head forging with a diameter of 4.5 meters, a height of 2.5 meters, and a wall thickness of 300 mm, ultimately completing the manufacturing of a high-purity, high-homogeneity nuclear power pressure vessel water chamber head forging.

[0071] The results of the embodiments show that the nuclear power pressure vessel forgings produced by the method of the present invention not only have good compositional homogeneity, but also good uniformity of mechanical properties, which greatly improves the comprehensive performance of the cylinder forgings and provides a new method for the high-purity and high-homogeneity manufacturing of nuclear power pressure vessel forgings.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel, characterized in that, Includes the following steps: The first step is to test the chemical composition of different locations of the same batch of continuous casting billets and select the continuous casting billets with similar chemical compositions as building blocks. The second step is to process the building blocks to the same dimensions (length, width, or diameter) and then clean their surfaces. The third step is to stack the cleaned homogenized building blocks. The fourth step is to place the stacked building blocks into a vacuum chamber for vacuum sealing; The fifth step is to heat and forge the packaged billet to form an integral blank; The sixth step is to shape the blank to the final required size; In the first step, the carbon segregation at different locations of the same continuous casting billet was less than 15%, and the carbon segregation at different batches of continuous casting billets was less than 20%. In the first step, a test block of the continuously cast billet that meets the chemical composition requirements is cut and forged, and the non-metallic inclusion content of the forged continuously cast billet is tested. The continuously cast billet that meets the technical conditions for non-metallic inclusions of the final forging is selected as the building block. The non-metallic inclusion content is 0.5 grade for A, B and C type inclusions and 1.0 grade for D type coarse inclusions. In the third step, during stacking, continuously cast billets with large chemical composition deviations from different furnace numbers are stacked crosswise to make the overall billet uniform after stacking.

2. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 1, characterized in that, In the first step, when testing the chemical composition of the continuously cast billet, the same batch of continuously cast billets should include at least the head billet and the tail billet. The sampling locations should include at least 1 / 2 of the width of the upper or lower surface of the continuously cast billet, the geometric center of the cross-section, and 1 / 2 of the thickness of the side surface. For different batches of continuously cast billets, the head billet and the tail billet of each batch should be tested separately.

3. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 1, characterized in that, The test block is taken at the middle of the width of the head or tail of the continuously cast billet, and the length and width of the test block are greater than or equal to the thickness of the continuously cast billet.

4. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 1, characterized in that, Forging ratio ≥ 3.

0.

5. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 1, characterized in that, In the third step, after stacking, the misalignment of two adjacent slabs after alignment is less than 2mm, and the gap is less than 1mm.

6. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 5, characterized in that, After stacking, the misalignment of two adjacent slabs after alignment is less than 1mm, and the gap is less than 0.5mm.

7. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 1, characterized in that, In the fifth step, the heating temperature is 0.8~0.9T. m T m The value is the melting point of the material, expressed in °C. The reduction for forging the billet is 10% to 60%.

8. The method for manufacturing a high-purity, high-homogeneity nuclear power pressure vessel according to claim 1, characterized in that, In the sixth step, when manufacturing the cylinder of the nuclear power pressure vessel, it is rolled into a cylinder forging by rolling, punching, reaming, or reaming and then rolling.

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