Method for forming eccentric forging for reactor control rod transition member housing

Abstract

A method for forming an eccentric forging for a reactor control rod transition member housing. The method comprises: by means of simulation technology, designing and manufacturing a mold and determining a forging process for a forging; selecting a steel ingot that meets forging requirements; forging the steel ingot according to the forging process and the mold for the forging, to obtain a preliminary forging; and machining the preliminary forging, to obtain a final forging. The present method achieves overall forming of the control rod housing forging, saving materials and shortening the processing cycle. Furthermore, the mold is reusable, leading to high production efficiency and significantly improved product quality stability.

Description

Eccentric forging forming method for control rod transition piece housing in reactor Technical Field

[0001] The invention relates to the field of nuclear power plant reactor equipment manufacturing, in particular to an eccentric forging forming method for a control rod transition piece housing in a reactor. Background Art

[0002] Control rod transition piece shell forgings are used in the manufacture of control rod drive mechanisms in reactor internals. They are one of the components of nuclear power plant reactors and an important moving part. Their function is to control the reactivity of the core. The quality of their performance directly affects the reliability and safety of nuclear reactor operation. They are one of the indispensable nuclear power equipment.

[0003] In recent years, with the continuous advancement of technology and the increasing requirements for safe operation of nuclear power plants, magnetically lifted control rod drive mechanisms (CRDMs) have become a mainstream product in the market. According to the "2022-2027 China CRDM Industry Market In-depth Research and Development Prospects Forecast Report" released by the Xinshijie Industry Research Center, CRDMs, due to their contact with the reactor coolant, require excellent resistance to high temperatures, high pressures, corrosion, and radiation. Furthermore, during reactor operation, reactor reactivity fluctuates widely, and the CRDMs undergo frequent movement, requiring excellent shock, vibration, and wear resistance, as well as operational stability and ease of maintenance. Overall, CRDMs place high demands on structural design, material selection, and manufacturing processes, resulting in high technical barriers to R&D and manufacturing. As a nuclear island component, the CRDM market is expanding. my country's overall nuclear power equipment development is at an internationally advanced level, and CRDM manufacturing capabilities should also be continuously strengthened. Summary of the Invention

[0004] In view of the above-mentioned shortcomings, the present invention provides an eccentric forging forming method for the control rod transition piece housing in the reactor. The control rod transition piece housing forging is manufactured by a die forging process. The size of the forging blank is closer to the finished product. Compared with the previous process of using square forging blanks for machining, it saves materials and shortens the processing cycle. Moreover, after the process is solidified, the mold can be reused, the batch production efficiency is high, and the product quality stability is greatly improved.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] An eccentric forging forming method for a control rod transition piece housing in a reactor, the eccentric forging forming method for a control rod transition piece housing in a reactor comprising:

[0007] Design and manufacture molds and determine forging processes through simulation technology;

[0008] Select steel ingots that meet forging requirements;

[0009] Forging the steel ingot according to the forging process and die to obtain the initial forging;

[0010] The rough forging is machined to obtain the final forging.

[0011] According to one aspect of the present invention, forging a steel ingot to obtain a rough forging according to a forging process and a die further comprises: forging the steel ingot to obtain a blank by free forging; and forging the blank to obtain a rough forging by a die.

[0012] According to one aspect of the present invention, forging a steel ingot by free forging to obtain a billet includes: upsetting and drawing the steel ingot to refine the grains; during the last upsetting, one end of the steel ingot is drawn to a predetermined size to form a tail of the billet, and the other end of the steel ingot is drawn to a predetermined size to form a head of the billet, thereby obtaining a billet, wherein the tail of the billet is eccentrically arranged with respect to the central axis of the head, and the head is thicker than the tail.

[0013] According to one aspect of the present invention, forging a steel ingot to obtain a rough forging according to a forging process and a mold includes: inserting a blank into a mold and adjusting the verticality of the blank and the mold; upsetting the head in the mold until it is formed in a circular cavity of the head; turning the blank and the mold over and upsetting the tail until it is formed; demolding the blank to obtain a rough forging; and forging and rounding the middle of the rough forging to correct the size.

[0014] According to one aspect of the present invention, forging a steel ingot to obtain a preliminary forging according to a forging process and a die further comprises: performing hydrogen expansion treatment and normalizing heat treatment on the preliminary forging.

[0015] According to one aspect of the present invention, the selection of steel ingots that meet predetermined standards includes: selecting raw materials that meet forging requirements; smelting the raw materials in an alkaline electric furnace and adding aluminum to calm them to obtain molten steel; vacuum refining the molten steel; and vacuum pouring the molten steel into steel ingots.

[0016] According to one aspect of the present invention, designing and manufacturing a mold and determining a forging process for a forging using simulation technology includes: establishing a multi-field coupled numerical simulation model to simulate the forging process of the forging; completing the design of the mold and determining its manufacturing process flow by conducting a numerical simulation study on the forging process of the forging, and determining the forging process for the forging; obtaining the mold based on the design and manufacturing process flow of the mold.

[0017] According to one aspect of the present invention, the method further includes the following step: heat treating the rough forging before machining the rough forging.

[0018] According to one aspect of the present invention, before the initial forging is heat treated, it is subjected to rough machining before heat treatment to remove fine cracks and wrinkles on the forged surface formed by forging.

[0019] According to one aspect of the present invention, the rough forging is subjected to a performance test before being machined.

[0020] Advantages of the present invention: The eccentric forging forming method for a control rod transition piece housing in a reactor described in the present invention includes: designing and manufacturing a mold and determining a forging process using simulation technology; selecting a steel ingot that meets the forging requirements; forging the steel ingot according to the forging process and mold to obtain a preliminary forging; and machining the preliminary forging to obtain a final forging. The present invention establishes a multi-field coupled numerical simulation model, replacing some large-scale forging tests with computer simulation, and numerically simulates the temperature field, stress field, strain field, and strain rate field of the forging, as well as the flow state of the metal, defects, and microstructure evolution process. An optimized mold is used to address defects such as folding and streamline faults during the forming process, and a dedicated mold is used during the forming stage to achieve integral forming of the control rod housing forging, thereby saving materials and shortening the processing cycle. Furthermore, after the process is solidified, the mold can be reused, batch production efficiency is high, and product quality stability is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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 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 paying any creative work.

[0022] FIG1 is a schematic diagram of a forming method according to Example 1 of the present invention;

[0023] FIG2 is a schematic diagram of a forming method according to Example 2 of the present invention;

[0024] FIG3 is a schematic diagram of a forming method according to Example 3 of the present invention;

[0025] FIG4 is a heat treatment process curve diagram of the present invention;

[0026] FIG5 is a flow chart of forging a steel ingot to obtain a preliminary forging according to the forging process and die of the present invention;

[0027] FIG6 is a schematic structural diagram of the mold of the present invention;

[0028] FIG7 is a schematic structural diagram of the preliminary forging according to the present invention;

[0029] FIG8 is a process curve diagram of forging a steel ingot to obtain a preliminary forging according to the forging process and die of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 are within the scope of protection of the present invention. Example

[0031] As shown in FIG1 and FIG5-FIG8, the eccentric forging forming method for the control rod transition piece housing in the reactor comprises:

[0032] S1: Design and manufacture dies and determine forging processes through simulation technology

[0033] According to the finished size of the forging, a multi-field coupled numerical simulation model is established, and the finite element simulation technology is used to simulate the forging process of the forging; through the numerical simulation research of the temperature field, stress field, strain field and strain rate field of the forging, the flow state of the metal, the evolution of defects and microstructure during the forging process, the optimized mold is used to solve the defects such as folding and streamline faults in the forming process, and the simulation technology is used to perform simulation verification and design the mold cavity size to ensure the forging forming standard, complete the design of the mold and determine its manufacturing process flow, and determine the forging process of the forging; according to the design and manufacturing process flow of the mold, the mold is obtained.

[0034] In this embodiment, the design and manufacturing process of the mold includes forging drawing design, mold plan, design size and simulation, mold drawing design, mold forging, and mold processing.

[0035] In this embodiment, the forging solution is to forge a cylinder with a diameter of 1500*1000, with a through hole of 350 in the middle; and then process it on a lathe to the final size.

[0036] S2: Select steel ingots that meet forging requirements

[0037] In this example, SA-508 Gr.3 Cl.1 alloy steel was selected for forging. Material procurement should strictly adhere to chemical composition regulations to minimize the presence of impurities and other harmful elements. This material can be smelted using a basic electric furnace, aluminum killing, vacuum refining, and vacuum casting. Other processes that can ensure quality, equivalent to or superior to this, may also be used.

[0038] This embodiment uses an alkaline electric furnace, aluminum sedation, vacuum refining, and vacuum pouring to smelt the material. The specific process flow is as follows: melting the material to the mix ratio, EF arc melting, LF refining outside the furnace, VD vacuum degassing, and vacuum pouring. To ensure the purity and uniformity of the steel ingot, harmful gases such as hydrogen must be removed from the steel before and during pouring, and the molten steel must be vacuum-treated. Furthermore, the vacuum system must have sufficient energy to produce an evacuation capacity below 133 Pa. The contractor must also provide a component list for ladle analysis. The forgings will also undergo product chemical composition analysis, with samples taken from the inner surface of the end corresponding to the original ingot head. The chemical composition analysis sample method is conducted in accordance with ASME SA-751-2004.

[0039] The chemical composition of steel ingots (melting analysis and finished product analysis) shall comply with the following table:

[0040]

[0041] S3: Forging the steel ingot according to the forging process and die to obtain the initial forging

[0042] When forging the steel ingot, the initial forging temperature is ≥1150℃, the final forging temperature is ≥800℃, and the forging is carried out on a 5000-ton press with a total forging ratio of about 11.1.

[0043] Forging process of this embodiment:

[0044] S3.1 Free forging, tap the surface of the steel ingot, hot cut the head and tail of the steel ingot, and blank it into octagonal 480*1200;

[0045] Blanking into an octagonal shape can facilitate fixation during forging, making upsetting and drawing more convenient and quick, effectively reducing the difficulty of processing;

[0046] S3.2 Heat the steel ingot to ≥1150℃, keep it at this temperature for more than 1.5 hours and then take it out of the furnace. Upset the steel ingot to 600 and then stretch it into octagonal shape (480*1200) to refine the grains.

[0047] In actual forging, the steel ingot can be subjected to multiple upsetting and drawing processes to refine the grains;

[0048] S3.3 Heat the steel ingot to ≥1150℃, keep it at this temperature for more than 1.5 hours and then take it out of the furnace. Upset the forging blank to 600mm. Stretch one end of the steel ingot into an octagonal shape of 300*500mm to form the tail of the blank, leaving 800mm of the tail. Stretch the other end of the steel ingot to ∅650*330mm to facilitate mold insertion, and finally obtain the blank.

[0049] The center axis of the tail and head of the blank is eccentrically arranged, and the head is thicker than the tail;

[0050] S3.4 Heat the blank to ≥1150℃, keep it warm for more than 2 hours and then take it out of the furnace. Insert the blank into the mold with the head of the blank at the top and the tail at the bottom. Adjust the verticality of the blank and the mold. Upset the head in the mold and form it in the circular cavity of the head. Turn the blank and the mold over. After turning over, the tail of the blank will extend beyond a part of the mold. Upset the tail until it is formed. De-mold the blank to make a rough forging. After the rough forging is made, forge and round the middle of the rough forging to correct the size.

[0051] The verticality is less than or equal to 0.05.

[0052] The mold in this embodiment is a leak tray mold.

[0053] According to technical requirements, hydrogen expansion and normalizing heat treatment are carried out after forging to prevent white spot defects in forgings and improve the quality of forgings.

[0054] S4: Machining the initial forging to obtain the final forging

[0055] Special machining equipment is used to perform precision machining on forgings to ensure that product dimensions meet drawing requirements.

[0056] After obtaining the final forgings, they are subject to dimensional inspection, VT testing, UT testing, MT testing, PT testing, finished product labeling, clean packaging, and transportation. These multiple inspections ensure product quality.

[0057] Example 2:

[0058] As shown in FIG2 and FIG5-FIG8, the eccentric forging forming method for the control rod transition piece housing in the reactor includes:

[0059] S1: Design and manufacture dies and determine forging processes through simulation technology

[0060] According to the finished size of the forging, a multi-field coupled numerical simulation model is established, and the finite element simulation technology is used to simulate the forging process of the forging; through the numerical simulation study of the forging process of the forging, the simulation technology is used to perform simulation verification and design the mold cavity size to ensure the forging forming standard, complete the design of the mold and determine its manufacturing process flow, and determine the forging process of the forging; according to the design and manufacturing process flow of the mold, the mold is obtained.

[0061] In this embodiment, the design and manufacturing process of the mold includes forging drawing design, mold plan, design size and simulation, mold drawing design, mold forging, and mold processing.

[0062] In this embodiment, the forging solution is to forge a cylinder with a diameter of 1500*1000, with a through hole of 350 in the middle; and then process it on a lathe to the final size.

[0063] S2: Select steel ingots that meet forging requirements

[0064] In this example, SA-508 Gr.3 Cl.1 alloy steel was selected for forging. Material procurement should strictly adhere to chemical composition regulations to minimize the presence of impurities and other harmful elements. This material can be smelted using a basic electric furnace, aluminum killing, vacuum refining, and vacuum casting. Other processes that can ensure quality, equivalent to or superior to this, may also be used.

[0065] This embodiment uses an alkaline electric furnace, aluminum sedation, vacuum refining, and vacuum pouring to smelt the material. The specific process flow is as follows: melting the material to the mix ratio, EF arc melting, LF refining outside the furnace, VD vacuum degassing, and vacuum pouring. To ensure the purity and uniformity of the steel ingot, harmful gases such as hydrogen must be removed from the steel before and during pouring, and the molten steel must be vacuum-treated. Furthermore, the vacuum system must have sufficient energy to produce an evacuation capacity below 133 Pa. The contractor must also provide a component list for ladle analysis. The forgings will also undergo product chemical composition analysis, with samples taken from the inner surface of the end corresponding to the original ingot head. The chemical composition analysis sample method is conducted in accordance with ASME SA-751-2004.

[0066] The chemical composition of steel ingots (melting analysis and finished product analysis) shall comply with the following table:

[0067]

[0068] S3: Forging the steel ingot according to the forging process and die to obtain the initial forging

[0069] When forging the steel ingot, the initial forging temperature is ≥1150℃, the final forging temperature is ≥800℃, and the forging is carried out on a 5000-ton press with a total forging ratio of about 11.1.

[0070] Forging process of this embodiment:

[0071] S3.1 Free forging, tap the surface of the steel ingot, hot cut the head and tail of the steel ingot, and blank it into octagonal 480*1200;

[0072] Blanking into an octagonal shape can facilitate fixation during forging, making upsetting and drawing more convenient and quick, effectively reducing the difficulty of processing;

[0073] S3.2 Heat the steel ingot to ≥1150℃, keep it at this temperature for more than 1.5 hours and then take it out of the furnace. Upset the steel ingot to 600 and then stretch it into octagonal shape (480*1200) to refine the grains.

[0074] In actual forging, the steel ingot can be subjected to multiple upsetting and drawing processes to refine the grains;

[0075] S3.3 Heat the steel ingot to ≥1150℃, keep it at this temperature for more than 1.5 hours and then take it out of the furnace. Upset the forging blank to 600mm. Stretch one end of the steel ingot into an octagonal shape of 300*500mm to form the tail of the blank, leaving 800mm of the tail. Stretch the other end of the steel ingot to ∅650*330mm to facilitate mold insertion, and finally obtain the blank.

[0076] The center axis of the tail and head of the blank is eccentrically arranged, and the head is thicker than the tail;

[0077] S3.4 Heat the blank to ≥1150℃, keep it warm for more than 2 hours and then take it out of the furnace. Insert the blank into the mold with the head of the blank at the top and the tail at the bottom. Adjust the verticality of the blank and the mold. Upset the head in the mold and form it in the circular cavity of the head. Turn the blank and the mold over. After turning over, the tail of the blank will extend beyond a part of the mold. Upset the tail until it is formed. De-mold the blank to make a rough forging. After the rough forging is made, forge and round the middle of the rough forging to correct the size.

[0078] The verticality is less than or equal to 0.05.

[0079] The mold in this embodiment is a leak tray mold.

[0080] According to technical requirements, hydrogen expansion and normalizing heat treatment are carried out after forging to prevent white spot defects in forgings and improve the quality of forgings.

[0081] S4: Heat treatment of initial forgings

[0082] In order to achieve ideal performance indicators, based on the actual structural dimensions of the trial products, multi-point contact thermocouples are used to measure the actual surface temperature of the forging during heating, so as to more effectively control the temperature value; the maximum allowable deviation from the specified heat treatment temperature during the insulation period is ±10℃.

[0083] According to technical requirements, Q (quenching) + T (tempering) heat treatment is performed. Q: Heating temperature is 950-955°C, holding time is 3 hours and 25 minutes, and water cooling is used. T: Heating temperature is 655-660°C, holding time is 5 hours and 35 minutes, and air cooling is used. The heat treatment process curve is shown in Figure 4.

[0084] S5: Machining the initial forging to obtain the final forging

[0085] Special machining equipment is used to perform precision machining on forgings to ensure that product dimensions meet drawing requirements.

[0086] After obtaining the final forgings, they are subject to dimensional inspection, VT testing, UT testing, MT testing, PT testing, finished product labeling, clean packaging, and transportation. These multiple inspections ensure product quality.

[0087] Example 3:

[0088] As shown in FIG3 and FIG5-8, the eccentric forging forming method for the control rod transition piece housing in the reactor includes:

[0089] S1: Design and manufacture dies and determine forging processes through simulation technology

[0090] According to the finished size of the forging, a multi-field coupled numerical simulation model is established, and the finite element simulation technology is used to simulate the forging process of the forging; through the numerical simulation study of the forging process of the forging, the simulation technology is used to perform simulation verification and design the mold cavity size to ensure the forging forming standard, complete the design of the mold and determine its manufacturing process flow, and determine the forging process of the forging; according to the design and manufacturing process flow of the mold, the mold is obtained.

[0091] In this embodiment, the design and manufacturing process of the mold includes forging drawing design, mold plan, design size and simulation, mold drawing design, mold forging, and mold processing.

[0092] In this embodiment, the forging solution is to forge a cylinder with a diameter of 1500*1000, with a through hole of 350 in the middle; and then process it on a lathe to the final size.

[0093] S2: Select steel ingots that meet forging requirements

[0094] In this example, SA-508 Gr.3 Cl.1 alloy steel was selected for forging. Material procurement should strictly adhere to chemical composition regulations to minimize the presence of impurities and other harmful elements. This material can be smelted using a basic electric furnace, aluminum killing, vacuum refining, and vacuum casting. Other processes that can ensure quality, equivalent to or superior to this, may also be used.

[0095] This embodiment uses an alkaline electric furnace, aluminum sedation, vacuum refining, and vacuum pouring to smelt the material. The specific process flow is as follows: melting the material to the mix ratio, EF arc melting, LF refining outside the furnace, VD vacuum degassing, and vacuum pouring. To ensure the purity and uniformity of the steel ingot, harmful gases such as hydrogen must be removed from the steel before and during pouring, and the molten steel must be vacuum-treated. Furthermore, the vacuum system must have sufficient energy to produce an evacuation capacity below 133 Pa. The contractor must also provide a component list for ladle analysis. The forgings will also undergo product chemical composition analysis, with samples taken from the inner surface of the end corresponding to the original ingot head. The chemical composition analysis sample method is conducted in accordance with ASME SA-751-2004.

[0096] The chemical composition of steel ingots (melting analysis and finished product analysis) shall comply with the following table:

[0097]

[0098] S3: Forging the steel ingot according to the forging process and die to obtain the initial forging

[0099] When forging the steel ingot, the initial forging temperature is ≥1150℃, the final forging temperature is ≥800℃, and the forging is carried out on a 5000-ton press with a total forging ratio of about 11.1.

[0100] Forging process of this embodiment:

[0101] S3.1 Free forging, tap the surface of the steel ingot, hot cut the head and tail of the steel ingot, and blank it into octagonal 480*1200;

[0102] Blanking into an octagonal shape can facilitate fixation during forging, making upsetting and drawing more convenient and quick, effectively reducing the difficulty of processing;

[0103] S3.2 Heat the steel ingot to ≥1150℃, keep it at this temperature for more than 1.5 hours and then take it out of the furnace. Upset the steel ingot to 600 and then stretch it into octagonal shape (480*1200) to refine the grains.

[0104] In actual forging, the steel ingot can be subjected to multiple upsetting and drawing processes to refine the grains;

[0105] S3.3 Heat the steel ingot to ≥1150℃, keep it at this temperature for more than 1.5 hours and then take it out of the furnace. Upset the forging blank to 600mm. Stretch one end of the steel ingot into an octagonal shape of 300*500mm to form the tail of the blank, leaving 800mm of the tail. Stretch the other end of the steel ingot to ∅650*330mm to facilitate mold insertion, and finally obtain the blank.

[0106] The center axis of the tail and head of the blank is eccentrically arranged, and the head is thicker than the tail;

[0107] S3.4 Heat the blank to ≥1150℃, keep it warm for more than 2 hours and then take it out of the furnace. Insert the blank into the mold with the head of the blank at the top and the tail at the bottom. Adjust the verticality of the blank and the mold. Upset the head in the mold and form it in the circular cavity of the head. Turn the blank and the mold over. After turning over, the tail of the blank will extend beyond a part of the mold. Upset the tail until it is formed. De-mold the blank to make a rough forging. After the rough forging is made, forge and round the middle of the rough forging to correct the size.

[0108] The verticality is less than or equal to 0.05.

[0109] The mold in this embodiment is a leak tray mold.

[0110] According to technical requirements, hydrogen expansion and normalizing heat treatment are carried out after forging to prevent white spot defects in forgings and improve the quality of forgings.

[0111] S4: Rough machining of the initial forgings before heat treatment.

[0112] The purpose of rough machining before heat treatment is to remove surface defects such as fine cracks and wrinkles formed during forging. This prevents the possibility of defects being amplified during the subsequent heat treatment phase. The smooth surface after machining allows for better ultrasonic testing, enabling timely detection of substandard quality issues within the forging. Repairable parts can be promptly repaired to prevent amplified defects and resulting in scrap. Unrepairable parts can be promptly scrapped for rework, effectively preventing wasteful subsequent processing of substandard parts.

[0113] S5: Heat treatment of initial forgings

[0114] In order to achieve ideal performance indicators, based on the actual structural dimensions of the trial products, multi-point contact thermocouples are used to measure the actual surface temperature of the forging during heating, so as to more effectively control the temperature value; the maximum allowable deviation from the specified heat treatment temperature during the insulation period is ±10℃.

[0115] According to technical requirements, Q (quenching) + T (tempering) heat treatment is performed. Q: Heating temperature is 950-955°C, holding time is 3 hours and 25 minutes, and water cooling is used. T: Heating temperature is 655-660°C, holding time is 5 hours and 35 minutes, and air cooling is used. The heat treatment process curve is shown in Figure 4.

[0116] S6: Performance testing of initial forgings

[0117] Take samples and perform performance tests on the initial forgings according to product technical requirements.

[0118] In this embodiment, the raw forgings are sampled and tested for performance. Specifically, the following steps are performed: sample cutting; simulated post-weld heat treatment; sample processing; physical and chemical testing; rough machining of the sample; and UT testing. The simulated post-weld heat treatment is performed to ensure that the mechanical properties of the raw forgings remain unchanged after the heat treatment. Physical and chemical testing includes chemical analysis, physical testing, and metallographic examination, which can measure various performance data of the raw forgings. Ultrasonic testing (UT) is a harmless test that primarily detects surface defects in the raw forgings.

[0119] The performance assessment requirements for physical and chemical testing are shown in the following table:

[0120]

[0121] The measured data after physical and chemical testing of this embodiment are shown in the following table:

[0122]

[0123] The process requirements and measured results of the metallographic test in the physical and chemical test of this embodiment are as follows:

[0124] 1) Microstructure

[0125] Microstructure observation should be carried out at a magnification of 200 times, and metallographic photographs should be taken, which are of chorionite.

[0126] 2) Grain size (longitudinal section):

[0127] The grain size of the forging material is measured according to the GB / T6394-2017 method and the grain size is magnified 100 times. The actual grain size of the forging material should be finer than or equal to grade 5. The actual measured grain size is 6.5.

[0128] 3) Non-metallic inclusions

[0129] The non-metallic inclusion content of forging materials shall be evaluated according to ASTM E45-18 Method A. The content of various non-metallic inclusions shall meet the following requirements:

[0130] Class A inclusions (coarse and fine) ≤ 1.5, actual measured 0 / 0;

[0131] Class B inclusions (coarse and fine) ≤ 1.5, actual measured 0 / 0;

[0132] Class C inclusions (coarse and fine) ≤ 1.5, actual measured 0.5 / 0.5;

[0133] Class D inclusions (coarse and fine) ≤ 1.5, actual measured 0.5 / 0.5;

[0134] A+C≤2.0, actual measured level is 0.5 / 0.5;

[0135] B+D≤2.0, actual measured value is 0.5 / 0.5;

[0136] A+B+C+D≤4.0, actual measured value is 1.0 / 1.0;

[0137] S7: Machining the initial forging to obtain the final forging

[0138] Special machining equipment is used to perform precision machining on forgings to ensure that product dimensions meet drawing requirements.

[0139] After obtaining the final forgings, they are subject to dimensional inspection, VT testing, UT testing, MT testing, PT testing, finished product labeling, clean packaging, and transportation. These multiple inspections ensure product quality.

[0140] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An eccentric forging method for a control rod transition piece housing in a reactor, characterized in that: The eccentric forging forming method for a control rod transition piece housing in a reactor comprises: Design and manufacture molds and determine forging processes through simulation technology; Select steel ingots that meet forging requirements; Forging the steel ingot according to the forging process and die to obtain the initial forging; The rough forging is machined to obtain the final forging.

2. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 1, characterized in that: Forging the steel ingot to obtain the initial forging according to the forging process and the die includes: forging the steel ingot to obtain the blank by free forging; and forging the blank to obtain the initial forging by the die.

3. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 2, characterized in that: The process of forging a steel ingot by free forging to obtain a billet includes: upsetting and stretching the steel ingot to refine the grains; during the last upsetting, one end of the steel ingot is stretched to a predetermined size to form a tail of the billet, and the other end of the steel ingot is stretched to a predetermined size to form a head of the billet, thereby obtaining a billet, wherein the tail of the billet is eccentrically arranged with respect to the central axis of the head, and the head is thicker than the tail.

4. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 3, characterized in that: Forging a steel ingot to obtain a rough forging according to the forging process and die includes: inserting the blank into the die, adjusting the verticality of the blank and the die; upsetting the head in the die until it is formed in a circular cavity of the head; turning the blank and the die over, upsetting the tail until it is formed; demolding the blank to obtain a rough forging; forging and rounding the middle of the rough forging to correct the size.

5. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 2, characterized in that: Forging the steel ingot to obtain the initial forging according to the forging process and the die also includes: performing hydrogen expansion treatment and normalizing heat treatment on the initial forging.

6. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 1, characterized in that: The method of selecting a steel ingot that meets predetermined standards includes: selecting raw materials that meet forging requirements; smelting the raw materials in an alkaline electric furnace and adding aluminum to obtain molten steel; vacuum refining the molten steel; and vacuum pouring the molten steel into a steel ingot.

7. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 1, characterized in that: The design and manufacture of dies and determination of forging processes through simulation technology include: establishing a multi-field coupled numerical simulation model to simulate the forging process of forgings; completing the design of dies and determining their manufacturing process flow through numerical simulation research on the forging process of forgings, and determining the forging process of forgings; obtaining the dies according to the design and manufacturing process flow of the dies.

8. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 1, characterized in that: The following steps are also included: Before machining the rough forgings, the rough forgings are heat treated.

9. The eccentric forging forming method for a control rod transition piece housing in a reactor according to claim 8, characterized in that: Before heat treatment of the initial forgings, rough processing before heat treatment is performed to remove the fine cracks and wrinkles formed on the forging surface due to forging.

10. The eccentric forging forming method for a control rod transition piece housing in a reactor according to any one of claims 1 to 9, characterized in that: Before machining the rough forgings, the performance of the rough forgings is tested.

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