Forging die and forging forming method for difficult-to-deform nickel-based superalloy disc forging

Abstract

The present application relates to the field of difficult deformation high-temperature alloy forging technology, and particularly relates to a difficult deformation nickel-based high-temperature alloy disc forging die and a forging forming method. The forging die comprises n sets of die assemblies, and the die assemblies except the nth set of die assemblies each comprise an anvil, a split die, a die sleeve and a punch. The split die comprises left and right side dies. The die sleeve is positioned and matched with the upper parts of the left and right side dies. The punch is matched with the cavity to realize local upsetting of the ingot. The nth set of die assemblies comprises an nth anvil, an nth punch and a die core. The nth anvil is provided with a lower cavity with an annular protrusion. The end face of the nth punch is provided with an upper annular protrusion. The die core penetrates the disc blank and is positioned in the hole of the anvil. The top of the die core is provided with a flying needle hole. The grain size of the obtained forging is uniform and controllable. The forging streamline is continuous and adapted to the direction of centrifugal tension, which significantly improves the fatigue strength and quality stability of the turbine disc forging.

Description

Technical Field

[0001] This invention relates to the field of forging technology for difficult-to-deform high-temperature alloys, specifically to a forging die and forging method for a difficult-to-deform nickel-based high-temperature alloy disc forging. Background Technology

[0002] The first step in the hot forging of deformed superalloy turbine disks is ingot preparation. Its core purpose is to break up the as-cast dendritic structure, obtaining a uniform, fine microstructure that meets grain size requirements, while simultaneously altering the ingot geometry to suit subsequent processing. For difficult-to-deform nickel-based superalloys, due to the addition of numerous alloying elements, the diameter of ingots prepared using electroslag remelting continuous directional solidification is typically limited to within 350 mm to reduce element segregation during solidification and ensure the uniformity of the material's chemical composition and microstructure.

[0003] In existing technologies, for high-temperature alloy ingots with a diameter of 350mm or less, their length typically does not exceed 2.5 times the diameter. This is because when the ratio of ingot height to diameter (height-to-diameter ratio) exceeds 2.5, instability is prone to occur during the upsetting process, leading to surface cracking and preventing the crystal structure from achieving the desired refinement. For the fabrication of large turbine disk forgings, existing technologies often employ a combined upsetting and drawing forging process. However, the drawing process in this process is difficult to achieve, and the flash of the forging easily overlaps with the edges, becoming a source of fatigue cracks and severely affecting the service life of the forging. Furthermore, the tubular inner hole of traditional forging dies has a draft taper, and after forging, the die and forging are easily locked due to thermodynamic and engineering mechanical factors. Glass lubricant or forging soft sleeves are required to assist in demolding, which not only increases process complexity but may also damage the surface crystal structure of the forging. Figure 1 As shown, using traditional forging equipment, punch 2 is a flat-bottom punch and anvil 1 is a flat-top anvil. Anvil 1 and punch 2 forge a cylindrical ingot with a diameter of less than 350mm to form a forged ingot, which includes a sufficiently refined crystallization zone 301, an upper insufficiently refined crystallization zone 302 and a lower insufficiently refined crystallization zone 303, and cannot achieve the standard grain size across the entire cross section.

[0004] Therefore, there is an urgent need to develop a new forging die and a corresponding forming method to solve problems such as forging instability, insufficient microstructure refinement, complex process flow, and poor fatigue performance of difficult-to-deform nickel-based superalloy ingots with a height-to-diameter ratio greater than 2.5. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a forging die and forging method for difficult-to-deform nickel-based superalloy disc forgings, thereby solving the technical problems in the prior art such as upsetting instability of difficult-to-deform nickel-based superalloy ingots with a height-to-diameter ratio greater than 2.5, insufficient microstructure refinement, high risk of fatigue cracking in forgings, complex process flow, and low material utilization, and obtaining large disc forgings with uniform grain size, reasonable forging flow lines, and high fatigue strength.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention provides a forging die for a difficult-to-deform nickel-based high-temperature alloy disc forging, comprising n sets of die components adapted to different forging times, n≥3, wherein all die components except the die component corresponding to the nth forging time include an anvil, a split die, a die sleeve and a punch.

[0008] The anvil is a rotating body with a frustum hole at its top and a circular plane at the bottom of the frustum hole; the frustum hole is used to position the split mold.

[0009] The split mold includes a left mold and a right mold with the same structure. Both the left mold and the right mold are half of a rotating body. After the left mold and the right mold are combined, they form a complete rotating body with a through cavity inside.

[0010] The mold sleeve has a ring structure and is positioned and engaged with the upper part of the left mold and the right mold;

[0011] The end of the punch is a punch dome, which contacts the upper end of the ingot. The punch and the cavity of the split mold cooperate to achieve local upsetting of the ingot. The ingot is turned over and placed in adjacent forging cycles. After n-1 forging cycles, the ingot forms a forging blank.

[0012] The die assembly for the nth forging includes the nth anvil, the nth punch, and the die core. The nth anvil has a lower cavity with a lower annular protrusion at the bottom. The end face of the nth punch has an upper annular protrusion corresponding to the lower annular protrusion.

[0013] The lower end of the mold core passes through the forging blank and is positioned with the central hole of the anvil of the nth anvil; the top of the mold core is provided with a flying needle hole, and after the forging blank is forged for the nth time, a turbine disk forging is formed.

[0014] Both the left mold and the right mold are provided with semi-circular truncated cones at the top and bottom. The lower semi-circular truncated cone is adapted to fit the anvil's truncated cone hole, and friction self-locking is formed by the mold taper.

[0015] The lower end face of the mold sleeve is provided with a conical positioning groove, which is adapted to fit and fits the upper semi-circular frustum of the left mold and the right mold, forming a frictional self-locking through the mold taper.

[0016] The cavity of the split mold includes a diameter-adaptive hole and a non-circular hole, wherein the diameter-adaptive hole is adapted to the outer diameter of the punch, and the non-circular hole has a central shrinkage structure.

[0017] The irregular hole shape of the split mold is determined by simulating the upsetting process of the workpiece to be forged and based on the distribution of the free deformation zone within the deformation area, so as to achieve uniform deformation and grain size control of the ingot.

[0018] The end face of the nth punch is also provided with an inner height stop and an outer height stop located inside and outside the upper annular protrusion, respectively. The inner height stop is used to position the mold core, and the outer height stop is used to position and cooperate with the nth anvil.

[0019] The nth anvil has a central hole at its center, which is used to position the mold core.

[0020] The mold core is mushroom-shaped, with multiple flying needle holes provided on its mushroom head.

[0021] The ingot is made of a difficult-to-deform nickel-based high-temperature alloy and is cylindrical in shape, with a height-to-diameter ratio of 2.5 to 5.

[0022] Another aspect of the present invention provides a forging method for a difficult-to-deform nickel-based superalloy disc forging using the forging die described above, comprising the following steps:

[0023] Step S1: Prepare n sets of mold components, n≥3;

[0024] Step S2: Heat the mold assembly to 480℃-490℃ and keep it at that temperature for 4-4.5 hours;

[0025] Step S3: Hold the cylindrical alloy ingot at 1000℃-1050℃ for 18-20 hours;

[0026] Step S4: Place the heat-insulated ingot into the first set of mold components. The lower end of the ingot contacts the circular plane of the anvil, and the upper end contacts the lowest point of the punch dome. Drive the punch at a speed of 25mm / s-30mm / s to press the ingot locally until the outer circumference of the ingot matches the inner circumference of the split mold, and obtain the first forging.

[0027] Step S5: The first forging is held at 1000℃-1050℃ for 18-20 hours;

[0028] Step S6: Turn the first forging after heat preservation over and place it into the second set of mold components for the second forging to obtain the second forging.

[0029] Step S7: Repeat steps S5 to S6 to perform upsetting step by step until n upsetting forgings are completed to obtain the turbine disk forging.

[0030] The nth closed-die isothermal forging is performed using the nth set of die components. The die core, the nth punch, and the nth anvil form a triaxial compressive stress forging environment. The plastic flow is controllable through the flying needle hole on the die core.

[0031] The present invention has the following beneficial effects and advantages:

[0032] 1. This invention effectively solves the problem of upsetting instability in difficult-to-deform nickel-based high-temperature alloy ingots with a height-to-diameter ratio of 2.5-5. By using the cavity constraint of a split mold and multi-stage turning forging, surface cracking of the ingot is avoided, and a billet with high-quality surface is obtained.

[0033] 2. This invention achieves full fragmentation and dynamic recrystallization of the as-cast structure, and the average grain size of the forging can reach ASTM 8.0. The uniformity of the structure is significantly better than that of the prior art, thus improving the plasticity and mechanical properties of the material.

[0034] 3. This invention employs flashless triaxial compressive stress forging, guiding the forging streamline through the flying needle hole, making the streamline continuous and compatible with the direction of centrifugal tension during turbine disk operation, significantly reducing the risk of fatigue crack initiation and improving thermal and stress coupled fatigue strength.

[0035] 4. This invention eliminates the need for upsetting and drawing processes, simplifying the preparation process of large turbine disk forgings. It also avoids the use of traditional release agents, reduces damage to the surface structure of forgings, improves material utilization, and lowers production costs.

[0036] 5. The forging process of this invention has precise and controllable deformation, and the batch-produced forgings have good consistency and stability in quality. It is suitable for the industrial production of large disc forgings of difficult-to-deform nickel-based high-temperature alloys, and has important engineering application value and economic significance.

[0037] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is a cross-sectional schematic diagram of a traditional forging equipment;

[0041] Figure 2This is a three-dimensional schematic diagram of the first forging die in an embodiment of the present invention;

[0042] Figure 3 This is a schematic axial cross-sectional view of the first forging die in an embodiment of the present invention;

[0043] Figure 4 for Figure 3 Enlarged view of a portion of point A in the middle;

[0044] Figure 5 This is a schematic axial cross-sectional view of the second forging die in an embodiment of the present invention;

[0045] Figure 6 This is a schematic diagram of the axial cross-section of the forging die before forging in the nth forging stage of this invention.

[0046] Figure 7 This is a schematic diagram of the shaft cross-section after forging the nth forging die in an embodiment of the present invention;

[0047] Figure 8 for Figure 7 Enlarged view of a portion of point B in the middle;

[0048] Figure 9 This is an exploded view of the nth forging die in an embodiment of the present invention.

[0049] In the diagram: 1. Anvil; 2. Punch; 301. Sufficiently refined crystallization zone; 302. Upper insufficiently refined crystallization zone; 303. Lower insufficiently refined crystallization zone; 4. First anvil; 401. First anvil's frustum-shaped hole; 402. First anvil's circular plane; 5. First left-side mold; 501. First left-side mold's diameter half-hole; 502. First left-side mold's irregular half-hole; 503. First left-side mold's semi-frustum; 6. First right-side mold; 601. First right-side mold's diameter half-hole; 602. First right-side mold's irregular half-hole; 60 3. First right-side mold semi-circular platform; 7. First mold sleeve; 8. First punch; 801. Punch dome; 9. Ingot; 10. Forging blank; 11. Turbine disc forging; 1101. Wheel hub; 1102. Wheel assembly; 1103. Wheel rim; 12. nth anvil; 13. nth punch; 1301. Outer height stop; 1302. Inner height stop; 14. Mold core; 1401. Lower shank; 1402. Flying needle hole; 15. Crystal forging flow line I; 16. Crystal forging flow line II; 17. First-stage forging. Detailed Implementation

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 according to the specific circumstances.

[0051] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0052] See Figures 1 to 9 As shown, one embodiment of the present invention provides a forging die for a difficult-to-deform nickel-based high-temperature alloy disc forging, comprising n A set of mold components is adapted to forging at different firing temperatures, n≥3. Except for the mold component corresponding to the nth firing temperature, the other mold components include an anvil, a split mold, a mold sleeve, and a punch. The anvil is a rotating body with a frustum hole at its top and a circular plane at the bottom. The frustum hole is used to position the split mold. The split mold includes a left mold and a right mold with identical structures. Both the left and right molds are half rotating bodies. When the left and right molds are combined, they form a complete rotating body with a through cavity inside. The mold sleeve is a ring structure and is positioned and fitted with the upper part of the left and right molds. The end of the punch is a punch dome. The punch dome contacts the upper end of the ingot. The punch fits with the cavity of the split mold to achieve local upsetting of the ingot. The ingot is turned around and placed in adjacent firing temperatures to achieve uniform refinement of the billet from the inside to the outside. After n-1 firing temperatures, the ingot forms a forging blank.

[0053] The die assembly for the nth forging stage includes an nth anvil 12, an nth punch 13, and a die core 14. The nth anvil 12 has a lower cavity with a lower annular protrusion at the bottom. The end face of the nth punch 13 has an upper annular protrusion corresponding to the lower annular protrusion. The lower end of the die core 14 passes through the forging blank and is positioned with the anvil hole of the nth anvil 12. The top of the die core 14 has a flying needle hole 1402. After the forging blank undergoes the nth forging stage, a turbine disk forging is formed.

[0054] Furthermore, the upper and lower parts of the left and right molds are provided with semi-circular frustums. The lower semi-circular frustum is adapted to fit and fits into the anvil frustum hole, forming a frictional self-locking through the mold taper. The lower end face of the mold sleeve is provided with a conical positioning groove, which is adapted to fit and fits into the upper semi-circular frustums of the left and right molds, forming a frictional self-locking through the mold taper.

[0055] Specifically, the cavity of the split-type mold includes a diameter-matching hole and an irregularly shaped hole. The diameter-matching hole matches the outer diameter of the punch, while the irregularly shaped hole has a central shrinkage structure. The shape of the irregularly shaped hole in the split-type mold is determined by simulating the upsetting process of the workpiece to be forged, based on the distribution of the free deformation zone within the deformation area, to achieve uniform deformation and grain size control of the ingot. Addressing the characteristics of difficult-to-deform nickel-based superalloys—poor plasticity and high deformation resistance—the cavity shape of the split-type mold conforms to the distribution pattern of the free deformation zone of the billet. Through a combination of local constraint and release, it avoids instability phenomena such as bulging and cracking in the billet. Furthermore, the use of a large-diameter mold hole design reduces the stress gradient in the circumferential direction of the billet, further suppressing bulging and improving the recrystallization sufficiency of the microstructure near the circumferential surface of the billet.

[0056] See Figures 2 to 4 As shown, in an embodiment of the present invention, the mold assembly corresponding to the first forging includes a first anvil 4, a first left-side mold 5, a first right-side mold 6, a first mold sleeve 7, and a first punch 8. The first punch 8 has a punch dome 801, and the first anvil 4 has a first anvil frustum hole 401. The bottom of the first anvil frustum hole 401 is a first anvil circular plane 402. The first left-side mold 5 and the first right-side mold 6 are identical half-rotor bodies. The lower part of the first left-side mold 5 is a first left-side mold semi-frustum 503, and the inner side, from top to bottom, has a first left-side mold diameter half-hole 501 and a first left-side mold irregular half-hole 502. The lower part of the first right-side mold 6 is a first right-side mold semi-frustum 603, and the inner side, from top to bottom, has a first right-side mold diameter half-hole 601 and a first right-side mold irregular half-hole 602.

[0057] After the first left mold 5 and the first right mold 6 are combined into a whole rotating body, their bottom surfaces abut against the circular plane 402 of the first anvil. The frustum hole 401 of the first anvil is respectively attached to the semi-circular frustum 503 of the first left mold and the semi-circular frustum 603 of the first right mold, forming a frictional self-locking relationship of the mold taper.

[0058] After the first left mold 5 and the first right mold 6 are combined into a single rotating body, the positioning relationship between the upper end and the first mold sleeve 7 is the same as that between the lower end and the upper end. The first mold sleeve 7 is a circular rotating body. After the first left mold 5 and the first right mold 6 are combined into a single rotating body, the diameter half-hole 501 of the first left mold and the diameter half-hole 601 of the first right mold are adapted to the outer diameter of the first punch 8, ensuring that the force is transmitted evenly when the first punch 8 is stamping, and avoiding localized force concentration on the blank.

[0059] Before forging begins, the cylindrical ingot 9 has a height-to-diameter ratio of 2.5 to 5, with GH4065A being the preferred grade. Its lower end contacts the circular plane 402 of the first anvil, and its upper end contacts the lowest point of the punch dome 801 of the first punch 8. The contact shapes of the irregular half-hole 502 of the first left mold, the irregular half-hole 602 of the first right mold, and the punch dome 801 are all determined through simulation of the upsetting process of the workpiece to be forged. Based on the distribution of the upsetting deformation area and the condition of the free deformation zone, a specially designed internal cavity shape and size are created to achieve uniform and controllable grain size. After the first forging, the ingot 9 forms the first forging 17.

[0060] See Figure 5 As shown, the die assembly for the second forging stage is adapted to the next stage of deformation, where the forging is reversed. The lower end (the flat end in contact with the anvil) of the original first forging stage becomes the upper end, and the upper end (the curved deformation end in contact with the dome punch) of the original first forging stage becomes the lower end. Furthermore, it needs to adapt to the deformation amount and direction of the next forging stage. The second set of dies needs to be specifically designed based on this condition. Similarly, the cavity size and shape of subsequent forging dies are optimized step by step to adapt to the deformation requirements of the billet's "step-by-step upsetting."

[0061] Further, see Figure 6 As shown, the end face of the nth punch 13 is also provided with an inner height stop 1302 and an outer height stop 1301 located inside and outside the upper annular protrusion. The inner height stop 1302 is used to position the mold core 14, and the outer height stop 1301 is used to position and cooperate with the nth anvil 12.

[0062] See Figure 6 and 7 As shown, the nth anvil 12 has a central hole at its center, which is used to position the mold core 14. The mold core 14 is mushroom-shaped, and multiple flying needle holes 1402 are provided on its mushroom head.

[0063] In this embodiment, the ingot is made of a difficult-to-deform nickel-based high-temperature alloy and is cylindrical in shape, with a height-to-diameter ratio of 2.5 to 5.

[0064] This invention effectively solves the problem of upsetting instability in difficult-to-deform nickel-based superalloy ingots with a height-to-diameter ratio of 2.5-5. By using the cavity constraint of a split mold and multi-stage forging, the original insufficiently refined crystallization zone of the billet is switched to the core stress zone. Under the constraint of the mold, it undergoes secondary stamping, eliminating dead zones in the microstructure refinement, achieving full fragmentation and dynamic recrystallization of the as-cast microstructure. The average grain size of the forging can reach ASTM 8.0, and the microstructure uniformity is significantly better than that of the prior art. This improves the plasticity and mechanical properties of the material, avoids surface cracking of the ingot, and obtains billets with high-quality surface finish.

[0065] The final forging stage of this invention employs flashless triaxial compressive stress forging. The forging streamline is guided through a flying needle hole, ensuring continuity and alignment with the centrifugal tension direction during turbine disk operation. This significantly reduces the risk of fatigue crack initiation and improves thermal and stress-coupled fatigue strength. Eliminating the need for upsetting and drawing processes simplifies the fabrication process for large turbine disk forgings. It also avoids the use of traditional release agents, reducing damage to the forging surface structure, improving material utilization, and lowering production costs. The deformation during forging is precisely controllable, resulting in consistent and stable quality in batch production. This method is suitable for the industrial production of large, difficult-to-deform nickel-based superalloy disk forgings, possessing significant engineering application value and economic significance.

[0066] Another embodiment of the present invention provides a forging method for a difficult-to-deform nickel-based superalloy disc forging using the forging die described above, comprising the following steps:

[0067] Step S1: Prepare n sets of mold components, n≥3; ensure that each set of mold components is suitable for the forging deformation requirements of the corresponding firing process;

[0068] Step S2: Heat the mold assembly to 480℃-490℃ and keep it at that temperature for 4-4.5 hours to prevent the surface of the ingot from cracking due to excessive temperature difference when the mold comes into contact with the high-temperature ingot.

[0069] Step S3: Place the cylindrical alloy ingot (height-to-diameter ratio 2.5-5) prepared by electroslag remelting continuous directional solidification process into a heating furnace and hold it at 1000℃-1050℃ for 18-20 hours to fully eliminate the internal stress of the ingot and improve the plasticity of the material.

[0070] Step S4: Place the heat-insulated ingot into the first set of mold components. The lower end of the ingot contacts the circular plane of the anvil, and the upper end contacts the lowest point of the punch dome. Drive the punch at a speed of 25mm / s-30mm / s to press the ingot locally under the cavity constraint of the split mold until the outer periphery of the ingot completely matches the inner wall of the cavity, completing the first forging and obtaining the first forging 17 with a concave top.

[0071] Step S5: The first forging 17 is held at 1000℃-1050℃ for 18-20 hours;

[0072] Step S6: Turn the first forging 17 after heat preservation upside down (concave side down) and put it into the second set of mold components for second forging to obtain the second forging;

[0073] Step S7: Repeat steps S5 to S6 to perform upsetting step by step until n upsetting forgings are completed to obtain turbine disk forging 11; turbine disk forging 11 includes a hub 1101, a wheel assembly 1102 and a rim 1103 connected from the inside to the outside.

[0074] In multi-stage forging, the temperature of the die and the billet coordinates to ensure the material remains within its optimal plasticity range, reducing deformation resistance. During adjacent forging stages, the forging is rotated vertically, forming an upsetting plate sequentially. After the (n-1)th forging stage, a forging blank 10 is obtained. This blank 10 is then heated and punched on a press to form an intermediate hole, preparing for subsequent die forging.

[0075] The forging blank 10 is subjected to the nth closed-die isothermal forging using the nth set of die components. The lower shank 1401 of the die core 14 penetrates the central hole of the forging blank 10 and the nth anvil 12. The die core, the nth punch, and the nth anvil form a closed cavity, creating a triaxial compressive stress forging environment. This allows the forging blank 10 to fully fill the cavity under triaxial compressive stress without flash. The flashing needle hole 1402 on the die core 14 guides the forging flow line, achieving triaxial compressive stress flashless forging.

[0076] See Figure 8 As shown, crystal forging flow line I15 flows from the inner edge to the flying needle hole 1402, and crystal forging flow line II16 flows from the rim 1103 through the wheel assembly 1102 to the hub 1101, finally obtaining the target disc forging.

[0077] In the embodiments of this invention, during adjacent forging cycles, the upper and lower ends of the forging and the die alternate between concave and flat, with the forging gradually becoming coarser to ensure refined grain size. This process eliminates the need for upsetting and drawing, simplifying the process flow and making it suitable for the preparation of large turbine disk forgings of difficult-to-deform high-temperature alloys. It effectively solves the limitation of existing high-temperature alloy large turbine disk forging methods, which are only applicable to high-temperature alloy ingots with a diameter of less than 350mm and a length not exceeding 2.5 times the diameter. This is because when the ratio of ingot height to diameter exceeds 2.5, instability occurs during upsetting, causing surface cracking and preventing the material's crystal structure from meeting ideal requirements. This invention uses a split die, avoiding the damage to the surface crystal structure of the casting caused by roughening, and eliminating the need for a draft angle. This invention employs flash-free triaxial compressive stress forging, ensuring the continuity of the forging flow line at locations prone to fatigue and heat treatment microcracks, such as edges and rims, effectively controlling the forging flow line and forging shape accuracy. Controlling the forging flow line direction to be close to the centrifugal tension direction helps improve the thermal and stress coupling fatigue strength.

[0078] This invention effectively solves the problems of upsetting instability and insufficient microstructure refinement in difficult-to-deform nickel-based superalloy ingots with a height-to-diameter ratio greater than 2.5. The resulting forgings have uniform and controllable grain size (average grain size can reach ASTM 8.0), continuous forging flow lines that are adapted to the direction of centrifugal tension, significantly improving the fatigue strength and quality stability of turbine disk forgings, while also increasing material utilization and simplifying the process flow. It is suitable for the mass production of large, difficult-to-deform nickel-based superalloy disk forgings.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A forging die for a difficult-to-deform nickel-based high-temperature alloy disc forging, characterized in that, Includes n sets of mold components adapted to different forging times, n≥3. Except for the mold component corresponding to the nth forging time, the other mold components include an anvil, a split mold, a mold sleeve and a punch. The anvil is a rotating body with a frustum hole at its top and a circular plane at the bottom of the frustum hole; the frustum hole is used to position the split mold. The split mold includes a left mold and a right mold with the same structure. Both the left mold and the right mold are half of a rotating body. After the left mold and the right mold are combined, they form a complete rotating body with a through cavity inside. The mold sleeve has a ring structure and is positioned and engaged with the upper part of the left mold and the right mold; The end of the punch is a punch dome, which contacts the upper end of the ingot. The punch and the cavity of the split mold cooperate to achieve local upsetting of the ingot. The ingot is turned over and placed in adjacent forging cycles. After n-1 forging cycles, the ingot forms a forging blank. The die assembly for the nth forging includes the nth anvil, the nth punch, and the die core. The nth anvil has a lower cavity with a lower annular protrusion at the bottom. The end face of the nth punch has an upper annular protrusion corresponding to the lower annular protrusion. The lower end of the mold core passes through the forging blank and is positioned with the central hole of the anvil of the nth anvil; the top of the mold core is provided with a flying needle hole, and after the forging blank is forged for the nth time, a turbine disk forging is formed.

2. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 1, characterized in that, Both the left mold and the right mold are provided with semi-circular truncated cones at the top and bottom. The lower semi-circular truncated cone is adapted to fit the anvil's truncated cone hole, and friction self-locking is formed by the mold taper. The lower end face of the mold sleeve is provided with a conical positioning groove, which is adapted to fit and fits the upper semi-circular frustum of the left mold and the right mold, forming a frictional self-locking through the mold taper.

3. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 1, characterized in that, The cavity of the split mold includes a diameter-adaptive hole and a non-circular hole, wherein the diameter-adaptive hole is adapted to the outer diameter of the punch, and the non-circular hole has a central shrinkage structure.

4. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 3, characterized in that, The irregular hole shape of the split mold is determined by simulating the upsetting process of the workpiece to be forged and based on the distribution of the free deformation zone within the deformation area, so as to achieve uniform deformation and grain size control of the ingot.

5. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 1, characterized in that, The end face of the nth punch is also provided with an inner height stop and an outer height stop located inside and outside the upper annular protrusion, respectively. The inner height stop is used to position the mold core, and the outer height stop is used to position and cooperate with the nth anvil.

6. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 1, characterized in that, The nth anvil has a central hole at its center, which is used to position the mold core.

7. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 1, characterized in that, The mold core is mushroom-shaped, with multiple flying needle holes provided on its mushroom head.

8. The forging die for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 1, characterized in that, The ingot is made of a difficult-to-deform nickel-based high-temperature alloy and is cylindrical in shape, with a height-to-diameter ratio of 2.5 to 5.

9. A forging method for a difficult-to-deform nickel-based superalloy disc forging using the forging die described in any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Prepare n sets of mold components, n≥3; Step S2: Heat the mold assembly to 480℃-490℃ and keep it at that temperature for 4-4.5 hours; Step S3: Hold the cylindrical alloy ingot at 1000℃-1050℃ for 18-20 hours; Step S4: Place the heat-insulated ingot into the first set of mold components. The lower end of the ingot contacts the circular plane of the anvil, and the upper end contacts the lowest point of the punch dome. Drive the punch at a speed of 25mm / s-30mm / s to press the ingot locally until the outer circumference of the ingot matches the inner circumference of the split mold, and obtain the first forging. Step S5: The first forging is held at 1000℃-1050℃ for 18-20 hours; Step S6: Turn the first forging after heat preservation over and place it into the second set of mold components for the second forging to obtain the second forging. Step S7: Repeat steps S5 to S6 to perform upsetting step by step until n upsetting forgings are completed to obtain the turbine disk forging.

10. The forging method for the difficult-to-deform nickel-based high-temperature alloy disc forging according to claim 9, characterized in that, The nth closed-die isothermal forging is performed using the nth set of die components. The die core, the nth punch, and the nth anvil form a triaxial compressive stress forging environment. The plastic flow is controllable through the flying needle hole on the die core.

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