Forging method of elliptical ring forgings

Abstract

This invention discloses a forging method for an elliptical ring forging. The forging method includes: Step 1, pretreatment of the steel ingot; Step 2, controlled forging of the steel ingot to form a second preform; Step 2.1, performing a first upsetting and drawing operation on the entire steel ingot and a second upsetting operation to form a cylindrical first preform; Step 2.2, punching and reaming the first preform to obtain the second preform; during the reaming operation, the deformation rate of each reaming operation is gradually reduced, and the deformation rate of each reaming operation and the heating parameters are controlled; Step 3, controlled forging. This method can balance the forging deformation and dynamic recrystallization process, maintain and further optimize the fine-grained structure obtained by upsetting and drawing, improve the microstructure quality of the second preform, and has the advantages of high microstructure quality and good mechanical properties of the forged elliptical ring forging.

Description

Technical Field

[0001] This invention relates to the technical field of forging manufacturing and processing, and in particular to a forging method for an elliptical ring forging. Background Technology

[0002] The 600MW fast breeder reactor, a fourth-generation nuclear power plant, is a landmark project in my country's nuclear energy development. On one hand, it can increase uranium utilization from the current 1%-2% to 60%-70%, converting uranium-238, which accounts for approximately 99.2% of natural uranium, into fissile fuel. On the other hand, it can burn off long-lived actinides generated during nuclear power plant operation, converting them into easily disposed fission products, thus minimizing radioactive waste. Furthermore, the demonstration fast reactor possesses many inherent safety characteristics and passive safety features, making it extremely important in nuclear energy development.

[0003] Sodium-cooled fast reactors are the main reactor type for my country's development of fourth-generation advanced nuclear energy systems. The reactor vessel system is one of the most critical protective components of sodium-cooled fast reactors. The temperature of liquid metallic sodium inside the reactor vessel is high, exceeding 500°C. The normal operating temperature of the reactor vessel is 200-250°C, and the extreme operating temperature is as high as 650°C. The large temperature difference and thermal stress between the inside and outside and the complex operating conditions place extremely high demands on the performance of forgings. Forgings used in sodium-cooled fast reactors must have good thermal strength and ductility.

[0004] Conical nozzle forgings are key components of reactor vessels. These are elliptical annular forgings made of F316H steel. During manufacturing, their microstructure must achieve a grain size of 3.5–6, with a difference of less than 2 grades. However, current technology for forging elliptical annular forgings results in long production cycles and difficulty in ensuring uniform microstructure, leading to potential microstructural risks within the forging. Therefore, current technology typically forges conical nozzles into circular annular forgings for covering. However, since the delivered conical nozzle is elliptical, using circular annular forgings results in significant material waste. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of ensuring the uniformity of the microstructure of elliptical ring forgings during free forging of irregularly shaped forgings in the prior art. Therefore, this invention provides a forging method for elliptical ring forgings, which avoids the quality risks of conventional forging methods, significantly improves material utilization, shortens the manufacturing cycle of forgings, and produces large forgings with uniform grain structure and elliptical contoured conical nozzles, meeting the usage requirements of sodium-cooled fast reactor vessel systems.

[0006] To address the above problems, embodiments of the present invention provide a forging method for an elliptical ring forging, comprising:

[0007] Step 1, steel ingot pretreatment; including:

[0008] Heating the steel ingot to achieve high-temperature homogenization, and then subjecting the steel ingot to multiple light-pressure rounding operations;

[0009] Step 2: Controlled forging of the steel ingot to form the second preform, including:

[0010] Step 2.1: The steel ingot is subjected to the first upsetting and drawing operation and the second upsetting operation to form the first cylindrical preform;

[0011] Step 2.2: Punch and enlarge the first preform to obtain the second preform;

[0012] During the hole expansion operation, the deformation rate of a single hole expansion gradually decreases, and when the deformation rate of a single hole expansion is ≥50%, the furnace return parameters are 1200±20℃ and heat preservation for 10±3h.

[0013] When the single hole expansion deformation rate is ≥40%, the furnace parameters are 1200±20℃ and heat preservation for 8±2h.

[0014] When the single hole expansion deformation rate is ≥30%, the furnace parameters are 1200±20℃ and heat preservation for 6±1h;

[0015] When the single hole expansion deformation rate is ≥20%, the furnace parameters are 1100±20℃ and heat preservation for 5±1h.

[0016] When the single hole expansion deformation rate is ≤20%, the furnace parameters are 1050±20℃ and heat preservation for 3±0.5h;

[0017] Step 3: Shape-controlled forging of the second preform. The second preform is shaped using an arc-shaped anvil with an arc groove to form an elliptical ring forging.

[0018] The total forging ratio of elliptical ring forgings is greater than or equal to 10.

[0019] By employing the above technical solution, the steel ingot before punching and reaming can undergo two overall large deformation rate upsetting processes and one elongation, thereby breaking down the cast dendrites and forging internal porosity and voids, achieving the goal of refining the coarse grains inside the steel ingot and improving the compaction effect. Simultaneously, the aforementioned reaming method can balance the forging deformation and dynamic recrystallization process, maintaining and further optimizing the fine-grained structure obtained from upsetting and drawing, improving the microstructure quality of the second preform; the total forging ratio of the elliptical ring forging is greater than or equal to 10, resulting in the welding of internal pores and the breaking down of cast dendrites, significantly improving both the longitudinal and transverse mechanical properties of the elliptical ring forging.

[0020] In some embodiments, the steel ingot is made of high-carbon austenitic heat-resistant stainless steel and is formed using an AOD+ESR dual-process. This ensures the microstructure and properties of the steel ingot to be processed, providing a basis for ensuring the uniformity of the microstructure after the first preform is forged.

[0021] In some embodiments, step 1 includes:

[0022] Step 1.1: Heat the steel ingot to 1220℃~1240℃ and hold for 60-140h; this will allow the steel ingot to achieve high-temperature homogenization, thereby improving the segregation of the steel ingot and providing a basis for the uniformity of the forging structure of the steel ingot.

[0023] Step 1.2: Perform a light pressing and rounding operation on the steel ingot; the pressing amount of the light pressing and rounding operation is ≤50mm, and the anvil feed amount is 500~800mm;

[0024] Step 1.3: Repeat step 1.2 multiple times, and the misalignment of the anvil in the light pressing and rounding operation in two adjacent steps 1.2 is 300mm.

[0025] By adopting the above technical solution, multiple light-pressure rolling operations with small reductions can be performed before controlled forging of steel ingots to improve the surface quality, forgeability, and surface plasticity of steel ingots, thereby reducing the risk of surface cracking.

[0026] In some embodiments, step 1.1 uses a stepped heating method for the steel ingot, with an intermediate isothermal temperature of 900-1050°C, a heating rate not exceeding 100°C / h, and a holding time of (1.0-1.2h) / 100mm.

[0027] In some embodiments, step 1.2 is repeated more than three times in step 1.3, and the steel ingot is lightly pressed and rolled using an upper flat anvil with a width of 900 mm and a lower flat anvil with a width of 900 mm.

[0028] In some embodiments, the deformation amount of the first upsetting and the second upsetting is 40-60%. When performing the first upsetting and the second upsetting, the bottom surface of the steel ingot is supported by an upsetting stencil, and the top surface of the steel ingot is pressed down by a spherical upsetting plate.

[0029] In some embodiments, the outer diameter of the upsetting stencil is 2600 mm, the inner diameter is 830 mm, and the height is 1200 mm; the outer diameter of the spherical upsetting plate is 3200 mm and the height is 500 mm.

[0030] In some embodiments, during the lengthening operation:

[0031] The steel ingot is placed between the upper wide anvil and the lower wide anvil, and the width of the upper wide anvil and the width of the lower wide anvil are 1600mm, the length is 4500mm, and the thickness is 1500mm.

[0032] The single anvil reduction for both the upper and lower wide anvils is 20%–30%, and the anvil joining amount is 25%.

[0033] In some embodiments, during the first upsetting, drawing and second upsetting processes, the steel ingot is heated and held at a temperature of 1200–1240°C for 12 ± 3 hours.

[0034] In some embodiments, the length of the arc-shaped anvil is 3000±500mm, the height is 600±50mm, and the depth of the arc-shaped groove is 100±10mm;

[0035] Before performing the elliptical pressing operation, the second preform is preheated using heating parameters of 800℃~1000℃ for 3±1h.

[0036] By adopting the above technical solution, local deformation of the second preform can be avoided during controlled forging, and the arc integrity of the elliptical ring forging after forging can be guaranteed. At the same time, no large forging rheology occurs during controlled forging. In order to ensure the final grain structure of the elliptical ring forging, only heating parameters of holding at 800℃~1000℃ for 3±1h are used. While ensuring the quality of the final grain structure of the elliptical ring forging, the heating time and heating temperature are reduced, thereby improving processing efficiency.

[0037] Other features and corresponding beneficial effects of the present invention will be described in the latter part of the specification, and it should be understood that at least some of the beneficial effects will become obvious from the description in the specification. Attached Figure Description

[0038] Figure 1 This is a schematic flowchart of the forging method for an elliptical ring forging provided in an embodiment of the present invention.

[0039] Figure 2 A schematic diagram of the structure of the first preform for forging an elliptical ring is provided for an embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram of the structure of the first preform after punching, provided in an embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram of the structure of the second preform provided in an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of the arc-shaped anvil provided in an embodiment of the present invention;

[0043] Figure 6 This is a deformation diagram of the controlled forging of the second preform provided in an embodiment of the present invention. Detailed Implementation

[0044] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0045] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0046] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0050] It should be noted that the pump support conical nozzle is a typical large-diameter elliptical flange forging, or it can be understood as a large-diameter elliptical ring forging. In the prior art, in order to ensure the quality of the internal structure of the forging, the pump support conical nozzle is usually forged into a circular ring forging and covered with a circular ring forging. However, since the pump support conical nozzle itself is an elliptical forging, covering it with a circular ring forging will cause serious material waste. For example, when manufacturing a circular ring forging with an outer diameter of 4090mm, an inner diameter of 2635mm, and a height of 610mm, the forging weighs 37 tons and requires 45 tons of electroslag ingot forging. However, when using an elliptical forging scheme, the major axis of the inner and outer diameters of the forging is 4090mm and 3050mm, the minor axis is 3630mm and 2590mm, the wall thickness is 530mm, and the height is 610mm. In this case, while fulfilling the same function as the circular ring forging, the elliptical forging weighs about 29 tons and requires about 35 tons of steel ingot, which can significantly reduce material waste. More importantly, the elliptical forging forged in this application can also avoid the forging structure risk when directly forming a circular ring, especially the core structure risk of rear wall ring-type parts.

[0051] Please see Figures 1-6 , Figure 1 This is a schematic flowchart of the forging method for an elliptical ring forging provided in an embodiment of the present invention. Figure 2 A schematic diagram of the structure of the first preform for forging an elliptical ring is provided for an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the first preform after punching, as provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of the second preform provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the arc-shaped anvil provided in an embodiment of the present invention. Figure 6 This is a deformation diagram of the controlled forging of the second preform provided in an embodiment of the present invention.

[0052] like Figures 1-6 As shown, this application provides a forging method for an elliptical ring forging, comprising:

[0053] Step 1, steel ingot pretreatment; including:

[0054] Heating the steel ingot to achieve high-temperature homogenization, and then subjecting the steel ingot to multiple light-pressure rounding operations;

[0055] The steel ingot can be made of high-carbon austenitic heat-resistant stainless steel, and it is formed using an AOD+ESR dual-process smelting method. This ensures the microstructure and properties of the steel ingot to be processed, providing a foundation for guaranteeing the uniformity of the microstructure after the first preform is forged.

[0056] In one implementation, step 1 includes:

[0057] Step 1.1: Heat the steel ingot to 1220℃~1240℃ and hold for 60-140h; this will allow the steel ingot to achieve high-temperature homogenization, thereby improving the segregation of the steel ingot and providing a basis for the uniformity of the forging structure of the steel ingot.

[0058] In step 1.1, the steel ingot is heated using a stepped heating method, with an intermediate isothermal temperature of 900–1050℃. The heating rate during the process does not exceed 100℃ / h, and the holding time is (1.0–1.2h) / 100mm. Specifically, after the steel ingot is placed in the furnace, it is heated to 900–1050℃ at a rate of ≤100℃ / h and held for 15h. After the holding period, the temperature is increased to 1220℃–1240℃ at full furnace power and held for 100±10h. This maximizes the high-temperature homogenization of the steel ingot and improves the internal microstructure quality.

[0059] Step 1.2: Perform a light pressing and rounding operation on the steel ingot; the pressing amount of the light pressing and rounding operation is ≤50mm, and the anvil feed amount is 500~800mm;

[0060] Step 1.3: Repeat step 1.2 multiple times, with the misalignment of the anvil in each adjacent step 1.2 light-pressure rounding operation being 300mm. In one embodiment, step 1.3 repeats step 1.2 more than 3 times, for example, 5 times, 6 times, or 8 times, and uses an upper flat anvil with a width of 900mm and a lower flat anvil with a width of 900mm to perform light-pressure rounding operations on the steel ingot. This allows for the improvement of the steel ingot surface quality, forgeability, and surface plasticity through multiple light-pressure rounding operations with small reductions before controlled forging of the steel ingot, thereby reducing the risk of surface cracking.

[0061] In one example, the steel ingot undergoes a light-pressure rounding operation.

[0062] Step 2: Controlled forging of the steel ingot to form the second preform, including:

[0063] Step 2.1: The steel ingot undergoes a first upsetting and drawing operation, followed by a second upsetting, to form a cylindrical first preform (e.g., Figure 2 (As shown). The diameter of the first preform is L, and the thickness is D.

[0064] In one embodiment, the deformation amount of the first and second upsetting is 40-60%. This large deformation upsetting process breaks down the cast dendrites inside the steel ingot and removes porosity and voids, refining the coarse grains within the ingot and improving its compaction. This ensures high-quality microstructure and properties of the forging blank, laying the foundation for forging high-standard, high-requirement elliptical ring forgings.

[0065] In one embodiment, during the first and second upsetting processes, the bottom surface of the steel ingot is supported by an upsetting stencil, and the top surface of the steel ingot is pressed down by a spherical upsetting plate. The upsetting stencil has an outer diameter of 2600 mm, an inner diameter of 830 mm, and a height of 1200 mm; the spherical upsetting plate has an outer diameter of 3200 mm and a height of 500 mm.

[0066] In one implementation, during the elongation operation:

[0067] The steel ingot is placed between the upper and lower wide anvils, both of which are 1600mm wide, 4500mm long, and 1500mm thick. The single-anvil reduction of the upper and lower wide anvils is 20%–30%, and the anvil-joining amount is 25%.

[0068] In one embodiment, during the first upsetting, drawing, and second upsetting processes, the steel ingot is heated and held at a temperature of 1200–1240°C for 12 ± 3 hours.

[0069] Step 2.1 involves two overall high-deformation-rate upsetting processes and one elongation of the steel ingot before punching and reaming operations. This process breaks down the cast dendrites and forges internal porosity and voids, refining the coarse grains inside the ingot and improving its compaction. This lays the foundation for forging high-standard, high-requirement elliptical ring forgings.

[0070] Step 2.2: Punch and enlarge the first preform to obtain the second preform;

[0071] During the hole expansion operation, the deformation rate of a single hole expansion gradually decreases, and when the deformation rate of a single hole expansion is ≥50%, the furnace return parameters are 1200±20℃ and heat preservation for 10±3h.

[0072] When the single hole expansion deformation rate is ≥40%, the furnace parameters are 1200±20℃ and heat preservation for 8±2h.

[0073] When the single hole expansion deformation rate is ≥30%, the furnace parameters are 1200±20℃ and heat preservation for 6±1h;

[0074] When the single hole expansion deformation rate is ≥20%, the furnace parameters are 1100±20℃ and heat preservation for 5±1h.

[0075] When the single hole expansion deformation rate is ≤20%, the furnace return parameters are 1050±20℃ and heat preservation for 3±0.5h.

[0076] Among them, the single-fire hole expansion deformation rate ε=(T0-T1) / T0×100%, T0 is the wall thickness before hole expansion, and T1 is the wall thickness after hole expansion.

[0077] In one example, the first preform is punched to form a shape like... Figure 3 The forging shown, wherein, Figure 3 The forging shown has an inner diameter of d1, an outer diameter of D1, and a height of H1; after multiple reaming operations, a second annular preform is formed (e.g., Figure 4 As shown in the figure, the inner diameter of the second preform is d2, the outer diameter is D2, and the height is H2;

[0078] at this time, Figure 3 The dimensional relationship between the forging and the second preform shown is as follows:

[0079] (D1 2 -d1 2 )×H1=(D2 2 -d2 2 )×H2;

[0080] Step 2.2 can produce a second preform in the shape of a ring (e.g., Figure 4 As shown in the figure, by controlling the deformation rate of a single firing and the heat preservation conditions in the furnace, the forging deformation and dynamic recrystallization process can be balanced, the fine grain structure obtained by upsetting and drawing can be maintained and further optimized, and the microstructure quality of the second preform can be improved.

[0081] Step 3: Shape-forging the second preform. The second preform is shaped using an arc-shaped anvil with an arc groove to form an elliptical ring forging.

[0082] The second preform is shaped using an arc-shaped anvil with an arc-shaped groove (e.g., Figure 6 As shown, this method can prevent the second preform from undergoing only local deformation during controlled forging, and can ensure the arc integrity of the elliptical ring forging after forging, thus guaranteeing the microstructure quality of the completed elliptical ring forging.

[0083] In one implementation, such as Figure 5 As shown, the length L of the arc-shaped anvil is 3000±500mm, the height H is 600±50mm, and the depth H1 of the arc-shaped groove is 100±10mm. Before performing the elliptical pressing operation, the second preform is preheated at a temperature of 800℃~1000℃ for 3±1h. Furthermore, the radius R of the arc-shaped groove is 2500~3500mm, and the angle α is 27±2°.

[0084] Since no significant forging rheology occurs during controlled forging, in order to ensure the final grain structure of the elliptical ring forging, only a heating parameter of holding at 800℃~1000℃ for 3±1h is used. This can ensure the quality of the final grain structure of the elliptical ring forging while reducing the heating time and temperature, thereby improving processing efficiency.

[0085] In one embodiment, the total forging ratio of the elliptical ring forging is greater than or equal to 10. This results in the welding of internal pores and the breaking down of cast dendrites in the elliptical ring forging, significantly improving both the longitudinal and transverse mechanical properties of the elliptical ring forging.

[0086] The following uses a specific pump support conical nozzle forging as an example to illustrate the entire forging process:

[0087] In one embodiment, the dimensions of the pump support tapered nozzle forging are as follows:

[0088] The outer and inner diameters are: major axis 4090mm, 3050mm, minor axis 3630mm, 2590mm, and height 610mm.

[0089] Forging weight: 29 tons

[0090] The manufacturing method includes the following steps:

[0091] (I) Steelmaking

[0092] Steel ingots are smelted using the AOD+ESR dual process.

[0093] The dimensions of the steel ingot are: riser end diameter Bottom diameter Height 2580mm.

[0094] Height / diameter ratio: 1.75.

[0095] Steel ingot weight: 35 tons.

[0096] (II) Pretreatment of steel ingots

[0097] After the bottom of the steel ingot is cleaned, it is sent to the forging workshop and placed in a heating furnace for high-temperature diffusion treatment.

[0098] After the steel ingot is put into the furnace, the temperature is raised to 900-1050℃ at a rate of ≤100℃ / hour and held for 15 hours.

[0099] After the heat preservation period, the furnace is heated to 1220℃~1240℃ at full power and kept warm for 100±10h.

[0100] (III) Forging

[0101] Forging is carried out on a 10,000-ton press.

[0102] The steel ingot is first stretched radially in five passes of "light pressing and rounding," with each pass reducing the ingot by 20mm and the stretching ratio being 1.15. The final dimensions after forging are... The height-to-diameter ratio of the forging billet is approximately 2.0.

[0103] First upsetting forging: The 1400mm forging billet is heated in the furnace and held at 1200~1240℃ for 11±2h before being taken out of the furnace for forging.

[0104] The forging billet was upsetting vertically along its height, reducing the height from 2780mm to 1200mm. The upsetting ratio was 2.31, the deformation was 56.8%, and the final forging dimension was 2130mm. The final forging temperature was measured to be 950℃.

[0105] First elongation forging: 2130 is held at 1200~1240℃ for 10±2h and then forged.

[0106] The forging billet is gradually stretched axially, with each of the initial four passes having a reduction of more than 20%. During the stretching process, it rotates radially, with a stretching ratio of 2.68. The final dimensions are as follows: The final forging temperature of the forging was measured to be 893℃.

[0107] Second upsetting forging: The 1350mm forging billet is heated in the furnace and held at 1200~1240℃ for 11±2h before being taken out of the furnace for forging.

[0108] The forging billet was vertically upsetting along its height, reducing the height from 2980mm to 610mm, with an upsetting ratio of 4.88 and a deformation of 79.5%. The final forging dimension was 2875mm. The measured final forging temperature was 910℃. After upsetting, the riser was cleaned, and the billet was reheated in the furnace. It was held at 1200–1240℃ for 5±1 hours before being punched using a φ950 / φ450×850mm hollow punch. The resulting hollow ring billet had dimensions of φ2930 / φ950×610mm.

[0109] After the billet is held at 1180~1200℃ for 3±1h, it is taken out of the furnace and expanded with a large deformation rate. During the process, the re-furnace parameters are set according to the correspondence between the single-fire expansion deformation rate and the re-furnace parameters.

[0110] After reaming, a second preform was obtained, with dimensions of φ3975 / φ2815×610mm. This preform was then heated in a furnace and held at 900℃ for 3±1 hours before being pressed into an ellipse. For the example forging, the anvil reduction was 345mm, meaning the ring blank was pressed from an outer diameter of 3975mm to an elliptical minor axis outer diameter of 3630mm. This pressure was held for 30±10 minutes. After the elliptical pressing was completed, the forging was immersed in water to cool to room temperature, resulting in an elliptical ring forging. The total forging ratio of the elliptical ring forging was 17.4.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A forging method for an elliptical ring forging, characterized in that, include: Step 1, steel ingot pretreatment; including: The steel ingot is heated to achieve high-temperature homogenization, and then subjected to multiple light-pressure rounding operations. Step 2: Controlled forging of the steel ingot to form a second preform, including: Step 2.1: The steel ingot is subjected to a first upsetting and drawing operation and a second upsetting operation to form a cylindrical first preform; Step 2.2: Punch and enlarge the first preform to obtain the second preform; During the hole expansion operation, the deformation rate of a single hole expansion gradually decreases, and when the deformation rate of a single hole expansion is ≥50%, the furnace return parameters are 1200±20℃ and the holding time is 10±3h. When the single hole expansion deformation rate is ≥40%, the furnace parameters are 1200±20℃ and heat preservation for 8±2h. When the single hole expansion deformation rate is ≥30%, the furnace parameters are 1200±20℃ and heat preservation for 6±1h; When the single hole expansion deformation rate is ≥20%, the furnace parameters are 1100±20℃ and heat preservation for 5±1h. When the single hole expansion deformation rate is ≤20%, the furnace parameters are 1050±20℃ and heat preservation for 3±0.5h; Step 3: Shape-controlled forging of the second preform, using an arc-shaped anvil with an arc groove to shape the second preform into an elliptical ring forging; The total forging ratio of the elliptical ring forging is greater than or equal to 10.

2. The forging method for the elliptical ring forging as described in claim 1, characterized in that, The steel ingot is made of high-carbon austenitic heat-resistant stainless steel, and it is formed by AOD+ESR dual-process smelting.

3. The forging method for the elliptical ring forging as described in claim 2, characterized in that, Step 1 includes: Step 1.1: Heat the steel ingot to 1220℃~1240℃ and hold for 60-140 hours; Step 1.2: Perform the light pressure rolling operation on the steel ingot; the pressing amount of the light pressure rolling operation is ≤50mm, and the anvil feed amount is 500~800mm; Step 1.3: Repeat step 1.2 multiple times, with the misalignment of the anvil in the light pressing and rounding operation in two consecutive steps 1.2 being 300mm.

4. The forging method for the elliptical ring forging as described in claim 3, characterized in that, In step 1.1, the steel ingot is heated in a stepped manner, with an intermediate isothermal temperature of 900~1050℃. The heating rate during the heating process does not exceed 100℃ / h, and the holding time is calculated based on the effective thickness, with a holding time of 1.0~1.2h per 100mm thickness.

5. The forging method for the elliptical ring forging as described in claim 3, characterized in that, In step 1.3, step 1.2 is repeated more than 3 times, and the steel ingot is subjected to the light pressure rolling operation using an upper flat anvil with a width of 900mm and a lower flat anvil with a width of 900mm.

6. The forging method for the elliptical ring forging as described in claim 1, characterized in that, The deformation amount of the first upsetting and the second upsetting is 40~60%. During the first upsetting and the second upsetting, the bottom surface of the steel ingot is supported by an upsetting stencil, and the top surface of the steel ingot is pressed down by a spherical upsetting plate.

7. The forging method for the elliptical ring forging as described in claim 6, characterized in that, The upsetting auger has an outer diameter of 2600mm, an inner diameter of 830mm, and a height of 1200mm; the spherical upsetting plate has an outer diameter of 3200mm and a height of 500mm.

8. The forging method for the elliptical ring forging as described in claim 6, characterized in that, During the lengthening operation: The steel ingot is placed between the upper wide anvil and the lower wide anvil, and the upper wide anvil and the lower wide anvil are 1600mm wide, 4500mm long, and 1500mm thick. The single anvil reduction amount of the upper and lower wide anvils is 20% to 30%, and the anvil connection amount is 25%.

9. The forging method of the elliptical ring forging as described in any one of claims 1 to 8, wherein during the first upsetting, the drawing operation and the second upsetting, the temperature at which the steel ingot is heated and held at a temperature of 1200~1240℃ and the heating and holding time is 12±3h.

10. The forging method of the elliptical ring forging as described in any one of claims 1 to 8, characterized in that, The arc-shaped anvil has a length of 3000±500mm, a height of 600±50mm, and a depth of 100±10mm. Before performing the elliptical pressing operation, the second preform is heated using heating parameters of 800℃-1000℃ for 3±1h.

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