Method for testing the adequacy of the head and tail cuts of steel ingots for heat transfer tubes

Abstract

The invention relates to a method for inspecting the adequacy of the head and tail resection of a steel ingot for a heat transfer tube, comprising the following steps: marking the head and tail of a steel ingot that has been head and tail resectioned; forging to obtain a forged bar, marking the head and tail and transplanting the mark; performing head and tail resection on the forged bar, sampling and analyzing both ends of the forged bar, and proceeding to the next step if the sampling and analysis results are qualified; dividing the forged bar after the head and tail resection into multiple short bars, marking the head and tail and transplanting the mark of each short bar; hot-extruding each short bar to obtain a corresponding extruded tube, marking the head and tail and transplanting the mark of each extruded tube; cold-rolling each extruded tube to obtain a corresponding heat transfer tube, marking the head and tail and transplanting the mark of the heat transfer tube; heat-treating the heat transfer tube, and inspecting the corresponding heat transfer tubes at the head and tail of the steel ingot one by one; evaluating the inspection results, tracing back to the head and tail of the steel ingot according to the numbers, and determining whether the head and tail resection of the steel ingot is sufficient.

Description

[0001] This application is a divisional application of the invention patent application with the application date of October 28, 2021, application number 2021112624519, and invention name "A method for checking the adequacy of head and tail cutting of steel ingots for nuclear power heat transfer tubes". Technical Field

[0002] The present invention relates to the technical field of raw material verification, and in particular to a method for inspecting the adequacy of head and tail cutting of steel ingots used for nuclear power heat transfer tubes. Background Art

[0003] Nuclear steam generator heat transfer tubes are a crucial component of the primary pressure boundary of a pressurized water reactor (PWR) nuclear power plant. They serve as a crucial barrier to prevent the leakage of radioactive fission products and are also the weakest link in the primary system. They are subjected to long-term service conditions of high temperature, high pressure, and high radiation dose media. These harsh operating environments can easily cause heat transfer tube failure or damage, making them crucial to the safe operation of nuclear power plants.

[0004] Steam generator heat transfer tubes, a critical component in nuclear power plants, are subject to high safety requirements, making material selection crucial. Typical steam generator heat transfer tubes are typically made of Inconel 690 alloy (designated NC30Fe in France and UNSN06690 in the United States), an austenitic, high-nickel-chromium iron alloy with excellent oxidation and corrosion resistance, resulting in a relatively high price.

[0005] Existing technology (RCC-M standards) only mentions a basic requirement for a minimum ingot head and tail resection rate, which is merely a minimum requirement for steam generator heat transfer tubes. However, for economic reasons, manufacturers often under-remove the raw steel ingot during production, resulting in substandard heat transfer tubes during subsequent manufacturing. Furthermore, the resection rate cannot be aligned with the original position in the ingot, making it impossible to determine whether the head and tail resection rate is sufficient. Summary of the Invention

[0006] In view of this, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a method for inspecting the adequacy of the head and tail resection of steel ingots for nuclear power heat transfer tubes, which can trace back to the original position of the steel ingot and determine whether the head and tail resection of the steel ingot is sufficient.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for inspecting the adequacy of the head and tail trimming of a steel ingot for a nuclear power heat transfer tube comprises the following steps: marking the head and tail of a steel ingot that has been head and tail trimmed; then forging the steel ingot to obtain a forged bar, marking the head and tail of the forged bar, and transplanting the markings; performing head and tail trimming on the forged bar, and sampling and analyzing both ends of the forged bar after the head and tail trimming. If the sampling and analysis results are qualified, the next step is carried out; if the sampling and analysis results are unqualified, it indicates that the head and tail trimming of the steel ingot is insufficient.

[0009] The forged bar after the head and tail are cut off is divided into multiple short bars, the head and tail of each short bar are marked and the mark is transplanted, and the multiple short bars are numbered in sequence according to the head and tail order corresponding to the original forged bar;

[0010] Each short bar is hot extruded to obtain an extruded tube. Each extruded tube is marked with the head and tail and the marking is transplanted. The number of the extruded tube is consistent with the number of the corresponding short bar.

[0011] Each extruded tube is cold-rolled to obtain a corresponding heat transfer tube, and the heat transfer tubes are marked with heads and tails and the marks are transplanted to finally obtain heat transfer tubes that are numbered one by one;

[0012] Heat treatment is performed on the numbered heat transfer tubes one by one, and multiple heat transfer tubes corresponding to the head and tail of the steel ingot are tested one by one;

[0013] The test results are evaluated and traced back to the head and tail of the ingot step by step according to the number to finally determine whether the head and tail of the ingot are sufficiently removed; that is, if the test results are qualified, it indicates that the head and tail of the previous ingot were sufficiently removed; if the test results are unqualified, it indicates that the head and tail of the previous ingot were not sufficiently removed.

[0014] According to some preferred embodiments of the present invention, the forging steps include at least one upsetting step and multiple drawing steps.

[0015] According to some preferred embodiments of the present invention, the forged bar is subjected to head and tail resection, and the total resection rate before and after forging must meet the following requirements: the head is greater than or equal to 5%, and the tail is greater than or equal to 7%, which are weight percentages.

[0016] According to some preferred embodiments of the present invention, sampling and analysis of both ends of the forged bar after head and tail resection includes finished product chemical composition analysis and non-metallic inclusion detection. Failure of the testing at both ends indicates insufficient head and tail resection of the forged bar or ingot. Passing the testing indicates sufficient head and tail resection of the forged bar, and subsequent steps can be used to determine whether sufficient resection of the ingot has occurred.

[0017] According to some preferred embodiments of the present invention, when forging bars are divided into short bars and marked and numbered: the forging bars after the head and tail are cut off are divided into m short bars, and the head and tail of each short bar are marked and the mark is transplanted. The m short bars are numbered in sequence as A1, A2...Am according to the head and tail sequence corresponding to the original forging bars.

[0018] According to some preferred embodiments of the present invention, when extruded tubes are cold-rolled to obtain heat transfer tubes and then labeled and numbered: if the extruded tubes are cut during the rolling process, the number of the original rolled tubes should be increased by one digit in sequence, and the head and tail labels and label transfer should be controlled to ultimately obtain individually numbered heat transfer tubes.

[0019] The process from extruded tube to finished tube undergoes multiple rolling passes (usually 3-5). Each rolling pass results in a change in outer diameter and / or wall thickness (generally a decrease), resulting in a corresponding increase in tube length. The tube number for the first rolling pass is typically the same as the extruded tube. However, as the tube length increases, it is segmented after each subsequent rolling pass until the final tube is rolled. For example, if the tube is segmented twice, each time into two sections, the heat transfer tubes are numbered A1-1-1, A1-1-2, A1-2-1, A1-2-2, and so on.

[0020] According to some preferred embodiments of the present invention, when testing heat transfer tubes after heat treatment, n heat transfer tubes corresponding to the head and tail of the steel ingot are inspected one by one, where 20≦n≦30. Typically, a single steel ingot can produce no fewer than 100 finished tubes, and numbering each tube individually is a significant workload. Tubes located in the middle of the ingot are generally of good quality, while tubes with quality issues are mostly located at the head and tail of the ingot. Therefore, the quality of the first and last 20-30 tubes is primarily assessed.

[0021] According to some preferred implementation aspects of the present invention, the inspection items are non-destructive testing and physical and chemical testing; the non-destructive testing items include visual inspection and ultrasonic testing; the physical and chemical testing items include finished product chemical composition analysis, room temperature tensile test, high temperature tensile test, hardness test, expansion test, grain size determination, and microstructure.

[0022] According to some preferred implementation aspects of the present invention, when dividing the forged bar into short bars, the forged bar is cut into sections along the main deformation direction of forging.

[0023] According to some preferred embodiments of the present invention, after vacuum smelting, the steel ingot undergoes defect removal and surface grinding at the head and tail of the vacuum ingot. The head and tail removal is increased based on surface quality, while the ends are flush. The processed vacuum ingot is electroslag remelted, and the cooled electroslag ingot is surface cleaned to remove visible defects. Marking control is implemented at the head and tail of the electroslag ingot, and the head and tail of the electroslag ingot are removed based on surface quality. The steel ingot stage primarily undergoes visual inspection to remove visible defects, such as oil stains, heavy skin, and debris. These defects are essentially visible to the naked eye, with the goal of preventing debris or contaminants from being carried into the next process.

[0024] In some embodiments of the present invention, the steel ingot is a vacuum smelting and electroslag remelting ingot commonly used for nuclear power steam generator heat transfer tubes. The typical manufacturing process of the heat transfer tube includes at least the following steps in sequence: forging → hot extrusion → cold rolling → final rolling annealing → special heat treatment → nondestructive testing → physical and chemical testing. The inspection method for verifying the adequacy of the head and tail removal of the steel ingot for nuclear power heat transfer tubes specifically includes the following steps:

[0025] (1) After vacuum smelting, the head and tail of the vacuum ingot are subjected to defect removal and surface grinding. On the basis of making both ends flush, the amount of removal at the head and tail is appropriately increased according to the surface quality;

[0026] (2) electroslag remelting the vacuum ingot (i.e., electrode) processed in step (1), cleaning the surface of the cooled electroslag ingot to remove visible defects, implementing marking control on the head and tail of the electroslag ingot, i.e., marking the head and tail, and performing head and tail removal on the electroslag ingot according to the requirements of relevant procedure documents and surface quality conditions;

[0027] (3) Rapid forging is performed on the electroslag ingot whose head and tail have been cut off in step (2), and finally a forged bar of a certain length is obtained after upsetting and stretching deformation. Head and tail identification control and identification transplantation are performed during the entire forging process, that is, the head and tail identifications of the corresponding steel ingot are transplanted to the head and tail of the forged bar; the forging fire times of rapid forging are one fire upsetting and multiple fire stretching;

[0028] (4) The forged bar obtained in step (3) is subjected to head and tail resection, and samples are taken at the positions corresponding to the head and tail ends of the electroslag ingot for finished product chemical composition analysis and non-metallic inclusion detection; the head and tail resection amount shall at least meet the requirements of the standard for the total head and tail resection rate; the standard here is the aforementioned requirement that the total resection rate before and after forging must meet the following requirements: the head is greater than or equal to 5%, and the tail is greater than or equal to 7%;

[0029] If the test and analysis results are qualified, proceed to the next step; if the test and analysis results are unqualified, it means that the head and tail removal of the bars and ingots is not sufficient;

[0030] (5) After the head and tail of the bar are cut off in step (4), the bar is sawn and divided into m short bars. The head and tail identification control and identification transplantation are performed on each short bar, where m is determined according to the size of the extrusion equipment in the next step. Each short bar is numbered A1, A2, ..., Am in the order corresponding to the head and tail of the original forged bar. The short bars are obtained by segmenting the forged bar along the main deformation direction (longitudinal direction);

[0031] (6) hot extrusion is performed on each small section of the bar in step (5), and each small section of the bar corresponds to an extruded tube. The extruded tube is subjected to head and tail identification control and identification transplantation, and the extruded tube number is consistent with the number of each small section of the bar;

[0032] (7) The extruded tube in step (6) is cold rolled. If the tube is split and cut during the rolling process, one number should be added sequentially based on the original rolled tube number, and the head and tail markings and marking transplantation should be controlled to finally obtain heat transfer tubes numbered one by one. For example, if the tube is split twice and each time is divided into two sections, the numbers are A1-1-1, A1-1-2, A1-2-1, A1-2-2, etc.; the cold rolling passes should be set according to the intermediate rolling specifications (outer diameter and wall thickness) set for the tube;

[0033] (8) heat treating the heat transfer tubes obtained in step (7) numbered one by one relative to the head and tail of the electroslag ingot, and performing nondestructive testing and physical and chemical testing on each of the n heat transfer tubes relative to the head and tail of the ingot, where 20≦n≦30;

[0034] Heat treatment is final rolling annealing + special heat treatment. Physical and chemical inspection items include but are not limited to finished product chemical composition analysis, room temperature tensile test, high-pressure tensile test, hardness test, expansion test, grain size determination, microstructure, etc. Non-destructive testing items include but are not limited to visual inspection, ultrasonic testing, etc.

[0035] (9) Evaluate the results of the nondestructive testing and physical and chemical testing of the n heat transfer tubes in step (8), trace the heat transfer tube numbers back to the head and tail of the electroslag steel ingot, and ultimately determine whether the head and tail of the steel ingot have been adequately removed. The control of head and tail identification and identification transplantation in the above steps involves sequentially transplanting the head and tail of the corresponding components in the previous process to the corresponding materials in this process, marking the head and tail, and continuously transplanting them to the materials in the subsequent processes to prevent confusion in the order of materials and confusion in correspondence; and facilitate subsequent sampling and tracing.

[0036] Due to the adoption of the above technical solution, compared with the prior art, the present invention is beneficial in that: the method for inspecting the adequacy of the head and tail cut of steel ingots for nuclear power heat transfer tubes of the present invention verifies whether the head and tail cut of the steel ingots are sufficient through reasonable corresponding numbering, tracking and inspection methods for each tube, using a limited number of heat transfer tubes, thereby solidifying the final verification of important process parameters such as the head and tail cut rate, and ensuring that the manufacturer can provide qualified products in a long-term and stable manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Attachment Figure 1 Schematic diagram of the manufacturing and inspection process of a heat transfer tube for inspecting the adequacy of the head and tail removal of a steel ingot in a preferred embodiment of the present invention;

[0039] Attachment Figure 2 Schematic diagram of marking and numbering of the head and tail of the forged bar relative to the ingot before segmentation in a preferred embodiment of the present invention;

[0040] Attachment Figure 3 Schematic diagram of marking and numbering of the head and tail of the forged bar after splitting and before extrusion relative to the ingot in a preferred embodiment of the present invention;

[0041] Attachment Figure 4 This is a schematic diagram of the marking and numbering of each short bar segment relative to the head and tail of the steel ingot after extrusion and before segmentation in a preferred embodiment of the present invention;

[0042] Attachment Figure 5 Schematic diagram of the marking and numbering of the head and tail of the extruded tube relative to the steel ingot after segmentation in a preferred embodiment of the present invention;

[0043] Attachment Figure 6 Schematic diagram of marking and numbering relative to the head and tail of the steel ingot after preliminary rolling and before splitting in a preferred embodiment of the present invention;

[0044] Attachment Figure 7 A schematic diagram of the marking and numbering of the head and tail of the steel ingot after the preliminary rolled tube is split in a preferred embodiment of the present invention;

[0045] Attachment Figure 8 Schematic diagram of the marking and numbering of the final rolled finished pipe relative to the head and tail of the steel ingot in a preferred embodiment of the present invention;

[0046] Attachment Figure 9 The present invention is a logic flow chart of a method for checking the adequacy of the head and tail cutting of steel ingots for nuclear power heat transfer tubes in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0048] The existing technology (RCC-M standard) only mentions the basic requirement for a minimum head and tail resection rate for steam generator heat transfer tubes, which is only the minimum requirement for steam generator heat transfer tubes. However, for economic reasons, manufacturers often do not remove enough raw steel ingots during the production stage, resulting in defective products in the subsequent heat transfer tube manufacturing process. If the heat transfer tubes are not numbered (relative to the head and tail of the ingot), tracked and inspected individually during the manufacturing process, the defective products cannot be mapped to their original positions in the ingot, and it is impossible to determine whether the head and tail resection of the ingot is sufficient. Therefore, during the first batch of steam generator heat transfer tube manufacturing, a complete steel ingot should be selected, and each heat transfer tube should be numbered according to its position in the ingot. The identification must be tracked and promptly transferred throughout the manufacturing process. In other words, a method of corresponding numbering and tracking is used throughout the manufacturing process to verify the adequacy of the head and tail resection of the ingot, and finally solidify the head and tail resection rate parameter for subsequent batch production.

[0049] like Figure 1 As shown, the steel ingot in this embodiment is a vacuum smelting + electroslag remelting ingot commonly used in nuclear power steam generator heat transfer tubes. The typical manufacturing process of the heat transfer tube includes at least the following steps in sequence: forging → hot extrusion → cold rolling → final rolling annealing → special heat treatment → non-destructive testing → physical and chemical testing.

[0050] like Figure 2-Figure 9 As shown, the inspection method for inspecting the adequacy of the head and tail removal of a steel ingot for a nuclear power heat transfer tube in this embodiment specifically includes the following steps:

[0051] (1) After vacuum smelting, the head and tail of the vacuum ingot are subjected to defect removal and surface grinding. On the basis of making both ends flush, the amount of removal at the head and tail is appropriately increased according to the surface quality.

[0052] (2) The vacuum ingot blank (i.e., electrode) processed in step (1) is electroslag remelted, the surface of the cooled electroslag ingot is cleaned, visual defects are removed, and the head and tail of the electroslag ingot are marked to indicate the head and tail. The head and tail of the electroslag ingot are cut off according to the requirements of the procedure document and the surface quality condition.

[0053] (3) Rapid forging is performed on the electroslag ingot whose head and tail have been cut off in step (2), and finally a forged bar of a certain length is obtained after upsetting and drawing deformation. Head and tail identification control and identification transplantation are performed during the entire forging process, that is, the head and tail identifications of the corresponding steel ingot are transplanted to the head and tail of the forged bar; the forging fire times of rapid forging are one upsetting fire and multiple drawing fires.

[0054] like Figure 2 As shown, it is the present invention Figure 1 The forged bars obtained after electric furnace refining, electroslag remelting and rapid forging in the manufacturing process are controlled by head and tail marking and marking transplantation throughout the entire process, ultimately ensuring that the head and tail markings at both ends of the forged bars are accurate.

[0055] (4) The forged bar obtained in step (3) is subjected to head and tail resection, and samples are taken at locations corresponding to the head and tail ends of the electroslag ingot for finished product chemical composition analysis and non-metallic inclusion detection; the head and tail resection amount at least meets the head and tail total resection rate requirements in the standard. The resection rate for the head and tail resection of the forged bar is: greater than or equal to 5% for the head and greater than or equal to 7% for the tail, and the above ratios are weight ratios.

[0056] If the test and analysis results are qualified, the next step will be carried out; if the test and analysis results are unqualified, it means that the head and tail of the steel ingot are not sufficiently cut. At this time, both ends of the forged bar are tested. If they fail, it means that the head and tail of the forged bar or steel ingot are not sufficiently cut; if they pass, it means that the head and tail of the forged bar are sufficiently cut, and the subsequent steps will be used to determine whether the steel ingot is sufficiently cut.

[0057] (5) After the head and tail of the bar are cut off in step (4), the bar is sawn and divided into m short bars. The head and tail identification control and identification transplantation are performed on each short bar, where m is determined according to the size of the extrusion equipment in the next step. Each short bar is numbered A1, A2, ..., Am in the order corresponding to the head and tail of the original forged bar. Figure 3 As shown, the short bars are obtained by cutting the forged bars into sections along the main forging deformation direction (longitudinal direction).

[0058] (6) Each small section of the bar in step (5) is subjected to hot extrusion, and each small section of the bar corresponds to an extruded tube. The extruded tube is subjected to head and tail identification control and identification transplantation, and the extruded tube number is consistent with the number of each small section of the short bar.

[0059] Specifically, in this embodiment, Figure 4 As shown, Figure 3 Each small section of forged bar is hot extruded to obtain an extruded tube. In principle, each small section of forged bar is extruded into an extruded tube. Therefore, each extruded tube and each small section of forged bar are numbered one by one, and the extruded tubes are numbered and marked at the head and tail.

[0060] like Figure 5 As shown, Figure 4 The extruded tube is divided into short extruded tubes of each small section. The specific specifications are determined according to the cold rolling equipment and the number of intermediate cold rolling times. Each short extruded tube after division is sequentially numbered and marked with the head and tail.

[0061] (7) The short extruded tube in step (6) is cold rolled. If the tube is split and cut during the rolling process, one number should be added sequentially based on the original rolled tube number, and the head and tail markings and marking transplantation should be controlled to finally obtain heat transfer tubes numbered one by one. For example, if the tube is split twice and each time is divided into two sections, the numbers are A1-1-1, A1-1-2, A1-2-1, A1-2-2, etc.; the number of cold rolling passes should be set according to the intermediate rolling specifications (outer diameter and wall thickness) set for the tube.

[0062] Specifically, in this embodiment, Figure 6 As shown, Figure 5 Each short extruded tube is rolled into an intermediate cold-rolled tube. In principle, each short extruded tube is rolled into an intermediate cold-rolled tube. Therefore, each short extruded tube and each intermediate cold-rolled tube are numbered one-to-one, and the intermediate cold-rolled tubes are numbered and marked at the head and tail.

[0063] like Figure 7 As shown, Figure 6 The specific specifications of each short cold-rolled tube after the intermediate cold-rolled tube is divided are determined according to the cold rolling equipment and the number of intermediate cold rolling times, and each short cold-rolled tube after division is sequentially numbered and marked at the head and tail.

[0064] like Figure 8 As shown, Figure 7 Each short cold-rolled tube segment is rolled to obtain a finished cold-rolled tube. In principle, each short cold-rolled tube segment is rolled to obtain a finished tube. Therefore, each short cold-rolled tube segment is numbered one-to-one with each finished tube, and the finished tubes are numbered and marked at the head and tail.

[0065] (8) Heat treatment is performed on the heat transfer tubes obtained in step (7) and numbered one by one relative to the head and tail of the electroslag ingot. The n heat transfer tubes relative to the head and tail of the steel ingot are subjected to nondestructive testing and physical and chemical testing items required by the standard one by one, where 20≦n≦30.

[0066] Heat treatment consists of final rolling annealing plus special heat treatment. Physical and chemical testing includes, but is not limited to, finished product chemical composition analysis, room temperature tensile testing, elevated tensile testing, hardness testing, flaring testing, grain size determination, and microstructure. Non-destructive testing includes, but is not limited to, visual inspection and ultrasonic testing.

[0067] (9) Evaluate the results of nondestructive testing and physical and chemical testing of the n heat transfer tubes in step (8), trace the heat transfer tube numbers back to the head and tail of the electroslag steel ingot, and ultimately determine whether the head and tail of the ingot have been adequately removed.

[0068] If the inspection finds that the five tubes near the head of the steel ingot are unqualified, then trace back to the steel ingot and increase the amount of head resection.

[0069] The control of head and tail identification and identification transplantation in the above steps is to transplant the head and tail of the corresponding parts in the previous process to the corresponding materials in this process in sequence, mark the head and tail, and continuously transplant them to the materials in the subsequent processes to prevent the material sequence from being confused and unable to correspond; it is convenient for subsequent sampling and traceability.

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for testing the adequacy of the head and tail removal of a steel ingot for a heat transfer tube, characterized in that: (1) After vacuum smelting, the steel ingot is subjected to defect removal and surface grinding at the head and tail of the vacuum ingot. On the basis of making both ends flush, the amount of removal at the head and tail is increased according to the surface quality; (2) electroslag remelting the vacuum ingot blank processed in step (1), cleaning the surface of the cooled electroslag ingot to remove visual defects, implementing marking control on the head and tail of the electroslag ingot, i.e., marking the head and tail, and performing head and tail removal on the electroslag ingot according to the surface quality condition; (3) Rapidly forging the electroslag ingot whose head and tail have been cut off in step (2), and finally obtaining a forged bar of a certain length after upsetting and stretching deformation. During the entire forging process, head and tail identification control and identification transplantation are performed, and the head and tail identifications of the corresponding steel ingot are transplanted to the head and tail of the forged bar; (4) performing head and tail resection on the forged bar obtained in step (3), and taking samples for analysis at the positions corresponding to the head and tail ends of the electroslag ingot; the head and tail resection amounts at least meet the requirements of the standard for the total head and tail resection rate: the head is greater than or equal to 5%, and the tail is greater than or equal to 7%, as percentages by weight; If the test and analysis results are qualified, proceed to the next step; if the test and analysis results are unqualified, it means that the head and tail removal of the bars and ingots is not sufficient; (5) sawing the bar after the head and tail are cut off in step (4) into m short bars, performing head and tail identification control and identification transplantation on each short bar, and numbering each short bar in the order of the head and tail of the original forged bar as A1, A2, ..., Am; (6) hot extrusion is performed on each small section of the bar in step (5), and each small section of the bar corresponds to an extruded tube. The extruded tube is subjected to head and tail identification control and identification transplantation, and the extruded tube number is consistent with the number of each small section of the bar; (7) The extruded tube in step (6) is cold rolled. If the tube is cut during the rolling process, a number should be added sequentially based on the original rolled tube number, and the head and tail markings and marking transfer should be controlled to finally obtain heat transfer tubes that are numbered one by one; (8) heat treating the heat transfer tubes obtained in step (7) numbered one by one relative to the head and tail of the electroslag ingot, and performing nondestructive testing and physical and chemical testing on each of the n heat transfer tubes relative to the head and tail of the ingot, where 20≦n≦30; (9) Evaluate the results of nondestructive testing and physical and chemical testing of the n heat transfer tubes in step (8), trace the heat transfer tube numbers back to the head and tail of the electroslag steel ingot, and ultimately determine whether the head and tail of the ingot have been adequately removed.

2. The method according to claim 1, characterized in that The control of head and tail identification and identification transplantation is to transplant the head and tail of the corresponding component in the previous step in sequence to the corresponding material in this step, mark the head and tail, and continuously transplant them to the material in the subsequent process.

3. The method according to claim 1, characterized in that The cold rolling passes in step (7) are set according to the intermediate rolling specifications set for the pipe.

4. The method according to claim 3, characterized in that The intermediate rolling specifications include the outer diameter and wall thickness of the pipe.

5. The method according to claim 1 or 3, characterized in that In step (7), multiple rolling passes are required from the extruded tube to the finished tube. The tube number of the first rolling is the same as the extruded tube number. As the length of the tube increases, it will be split after each subsequent rolling until the finished product is obtained after the last rolling pass.

6. The method according to claim 1, characterized in that The m in step (5) is determined based on the size of the extrusion equipment in step (6).

7. The method according to claim 1, characterized in that When the forged bar is divided into short bars in step (5), the forged bar is cut into sections along the main deformation direction of forging.

8. The method according to claim 1, characterized in that The forging fires in step (3) include at least one fire for upsetting and multiple fires for drawing.

9. The method according to claim 1, characterized in that The items for sampling and analyzing the two ends of the forged bar after the head and tail are cut off in step (4) include chemical composition analysis of the finished product and non-metallic inclusion detection.

10. The method according to claim 1, characterized in that The non-destructive testing items in step (8) include visual inspection and ultrasonic testing; the physical and chemical testing items include finished product chemical composition analysis, room temperature tensile test, high temperature tensile test, hardness test, expansion test, grain size determination, and microstructure.

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