Forging method for high-temperature alloy part with inner hole

Abstract

The invention discloses a forging method for a high-temperature alloy part with an inner hole, the forging process comprises pre-forging and finish-forging which are carried out in sequence, the pre-forging is used for increasing the dependent variable of a forging stock before finish-forging, a boss is arranged on an upper die of a finish-forging die, and the boss enables a concave part to be formed in the forging stock when the finish-forging die is closed; the boss is used for reducing the deformation dead zone of the forge piece. According to the method, the boss is designed on the finish forging die, meanwhile, the forging process is divided into the pre-forging stage and the finish forging stage, the blank deformation amount is increased through pre-forging before finish forging, and the subsequent deformation amount is more uniform; the two steps of pre-forging and finish-forging are combined with the design of a boss on a finish-forging die to play a role together, and the effect of eliminating the deformation dead zone of the forge piece is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of part forging, and in particular to a method for forging a high-temperature alloy part with an inner hole. Background Art

[0002] GH4169 is an important structural material, widely used in aviation and aerospace fields. Due to its excellent comprehensive performance at high temperatures, especially its high-temperature yield strength far exceeding that of other high-temperature alloys, it has become the most ideal material for critical parts of the engine.

[0003] The excellent strength performance of GH4169 high-temperature alloy is inseparable from its internal microstructure. For example, the high-quality GH4169 disc-shaft integrated parts of a certain aircraft engine, the most important condition to ensure that the forging meets the use requirements is the organizational distribution of the δ phase and the grain size and uniformity. Theoretically, the δ phase should be evenly distributed in granular or short rod shape. Due to the particularity of its working position, the grain size of the forging is required to be uniform and the grain size level is not less than 8.

[0004] However, in the actual forging process, whether it is free forging or die forging, it is difficult to avoid the appearance of insufficient deformation areas during the forming process, commonly known as "deformation dead zones"; and the larger the forging, the more difficult it is to deform, that is, the larger the "deformation dead zone"; and the deformation dead zone will lead to structural problems such as coarse grains. In addition, improper handling of the forging process may also cause the appearance of "black crystal" structures in the forgings that are not allowed.

[0005] A high-quality GH4169 hollow disc shaft integrated part (such as Figure 1 The traditional forging process of ) is to forge the steel sheet by die forging on a screw press (such as Fig.10 ), its forgings such as Fig.11 As shown in the figure, when the high-magnification structure is detected, the forgings appear at positions a and b. Fig.12 and Fig.13 The coarse grains, mixed grains and "black crystal phenomenon" shown directly lead to the forging being judged as unqualified.

[0006] The analysis found that a and b are in the deformation dead zone, and the true ε is only 0.02 ( Fig.14 ), with almost no deformation.

[0007] The patent with the publication number CN114535484A discloses a die and blanking process for improving the deformation dead zone of large-sized disc forgings, wherein the die comprises an upper die and a lower die, wherein a spherical crown-shaped upper protrusion is arranged on the upper die, and a spherical crown-shaped lower protrusion is arranged on the lower die, and the spherical crown-shaped upper protrusion and the spherical crown-shaped lower protrusion are arranged opposite to each other. The blanking process comprises the following steps: S1: the workpiece undergoes a first blanking process to obtain a first forging; the first forging undergoes a second blanking process to obtain a second forging; the second forging undergoes die forging to obtain a disc forging; S2: an alloy database is constructed using the Arrhenius equation; S3: a finite element simulation is performed on the forging process.

[0008] Although the above patent mentioned that its die can effectively reduce the generation of deformation dead zone on the end face of the workpiece, which is beneficial to the control of the grain structure on the end face of the disc forging, it has been found in practice that the measure of setting protrusions on the die is not enough to completely avoid the deformation dead zone. Therefore, how to further design the forging die or forging process, etc., in order to truly overcome the problem of deformation dead zone and even coarse grains and black grains, is a difficult problem in the current industry. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a forging method for high-temperature alloy parts with inner holes, which can effectively avoid deformation dead zones and ensure that the microstructure and properties of forgings meet technical requirements, in view of the defects of the prior art.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A forging method for a high-temperature alloy part with an inner hole, wherein the forging process includes pre-forging and final forging performed in sequence, wherein the pre-forging is used to increase the strain of the forging blank before the final forging, and the upper die of the final forging die is provided with a boss, wherein the boss forms a recessed portion on the forging blank when the final forging die is closed, and the boss is used to reduce the deformation dead zone of the forging.

[0012] Further, the pre-forging cavity of the pre-forging die is designed as follows:

[0013] S1. Known forging billet volume V after final forging 坯 and the total height H, and the diameter D of the original blank is obtained; Where n is the roughness ratio of the final forging head;

[0014] S2. According to the original billet diameter D, design the diameter W1 of the pre-forging cavity.

[0015] S3. Given the volume of the lower mold cavity of the final forging die, design the parting surface of the pre-forging die based on the principle that the volume of the lower mold cavity of the pre-forging die is equal to that of the final forging die.

[0016] Furthermore, both ends of the pre-forging cavity along the height direction are conical structures, and the conical height h1 of the conical structure satisfies h1>h / 4, where h is the length of the original blank; and the conical angle A of the conical structure satisfies A<45°.

[0017] Furthermore, a residual material groove is provided at the parting surface of the pre-forging die, and the residual material groove is formed by connecting S-shaped structures extending outward from the ends of the vertical wall surfaces of the upper die and the lower die of the pre-forging die, respectively, and the arc radius R of the S-shaped structure satisfies: Where V 坯料 is the original blank cutting volume, V 型腔 is the volume of the pre-forging cavity.

[0018] Furthermore, the boss on the final forging die is an elliptical boss, and the major axis a and the minor axis b of the elliptical boss satisfy: Where d is the inner hole diameter of the forging, k is the rigidity coefficient of the forging material, and z is the machining allowance of the forging.

[0019] Furthermore, M is the minimum allowance for forging finishing, m is the maximum offset of the forging, h0 is the depth of the defect layer on the surface of the forging, and x is the lower deviation value of the forging size.

[0020] Furthermore, the draft angle α of the final forging die satisfies: α<arctanμ, where μ is the friction coefficient between the forging and the final forging die.

[0021] Furthermore, the pre-forging die and the final forging die are integrated on the same die, and one-time die closing can achieve synchronous die closing of the pre-forging cavity and the final forging cavity.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The present invention designs a boss on the final forging die, and divides the forging process into two stages: pre-forging and final forging. The pre-forging is used to increase the deformation of the blank before the final forging, so that the subsequent deformation is more uniform; the pre-forging and final forging steps are combined with the boss design on the final forging die to work together to achieve the effect of eliminating the deformation dead zone of the forging.

[0024] 2) The integrated design of "one die with two cavities" for pre-forging and final forging dies can realize pre-forging and final forging in one fire, so that the forgings have sufficient deformation in one heating, reducing the transfer time and heating times.

[0025] 3) Optimize the forging process by increasing the mold preheating temperature, adding glass fiber insulation blankets in the mold cavity, and oil cooling after forging, so as to improve the uniformity of the forging structure, avoid the problems of coarse grains, black crystals, and mixed crystals, and ensure that the organizational performance of the forgings meets the technical requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of the GH4169 disk-shaft integrated component described in Example 1 of the present invention;

[0027] Figure 2 It is a cross-sectional view of the pre-forging cavity and the final forging cavity in the integrated die according to Example 1 of the present invention;

[0028] Figure 3 It is a partial cross-sectional view of the lower mold cavity of the pre-forging die and the lower mold cavity of the final forging die according to Example 1 of the present invention;

[0029] Figure 4 for Figure 2 Cross-sectional view of the middle residual trough;

[0030] Figure 5 for Figure 2 Cross-sectional view of the upper boss of the intermediate final forging die;

[0031] Figure 6 This is a schematic structural diagram of the original blank described in Example 2 of the present invention;

[0032] Figure 7 The pre-forging true strain field described in Example 2 of the present invention;

[0033] Figure 8 The true strain field after pre-forging and final forging described in Example 2 of the present invention;

[0034] Fig. 9 is the true strain field of the final forging without pre-forging in Comparative Example 1 of the present invention;

[0035] Fig.10 This is a schematic diagram of the traditional forging process of the GH4169 hollow disc-shaft integrated component;

[0036] Fig.11 for Fig. 9 Schematic diagram of the forging structure obtained by the forging process shown;

[0037] Fig.12 for Fig.11 Black crystal and coarse crystal phenomenon at positions a and b of the middle forging;

[0038] Fig.13 for Fig.11 Mixed crystal phenomenon at positions a and b of the middle forging;

[0039] Fig.14 for Fig. 9 True strain field of forging process. DETAILED DESCRIPTION

[0040] In order to clearly illustrate the technical features of the present solution, the present technical solution is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0042] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0043] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0045] Example 1

[0046] This embodiment provides a Figure 1 The blank forging method of the GH4169 hollow disk shaft integrated part shown in the figure is to design the forging die and determine the blank volume and height-to-diameter ratio according to the shape of the part. The forging process is divided into two stages, including pre-forging and final forging, wherein the pre-forging is used to increase the deformation of the forging blank before the final forging. After the pre-forging, the strain increases and the deformation is more uniform. In addition, the final forging die is as follows: Figure 2 As shown, both the upper die 1 and the lower die 2 are provided with bosses, which form a recessed portion on the forging blank when the final forging die is closed. The boss design combined with the added pre-forging operation can effectively eliminate the deformation dead zone of the forging; the boss on the upper die is the upper die boss 11, and the boss on the lower die is the lower die boss 21.

[0047] The pre-forging cavity of the pre-forging die is as follows: Figure 2 As shown, the design is as follows:

[0048] S1. Calculate the specifications of the original blank 3: The original blank is as follows Figure 6 As shown, the volume V of the forging blank (hereinafter referred to as the forging) after final forging is known. 坯 and the total height H, the diameter D of the original blank 3 is obtained; Where n is the roughness ratio of the final forging head;

[0049] The length h of the original blank 3 can be calculated using the above diameter D through the cylinder volume formula;

[0050] This embodiment is designed according to the final forging shape, and the forging volume V is obtained by volume calculation or simulation method. 坯 =3924548.6mm 3 Therefore, the original billet diameter D = 153mm, length h = 230mm, and the final original billet specifications are set to Φ160×235mm.

[0051] S2. Design of the pre-forging cavity 4: In order to further avoid deformation dead zones after the upper and lower end faces of the blank are formed during the forging process, it is preferred to design the two ends of the pre-forging cavity 4 along the height direction as a conical structure 41, that is, a double-cone pre-forging cavity, and its related parameters meet the following conditions, which can make the deformation of the original blank 3 after pre-forging greater than 20%, laying an excellent foundation for subsequent final forging.

[0052] The relevant parameter conditions are: the diameter of the pre-forging cavity 4 The cone height h1 of the cone structure 41 satisfies h1>h / 4; the cone angle A of the cone structure 41 satisfies A<45°. According to the above specific data, the maximum diameter of the pre-forging cavity W1=160mm, the cone angle A=40°, and the cone height h1=58mm.

[0053] S3. Parting surface design: The volume of the mold cavity under the final forging die is known, and the volume of the mold cavity under the pre-forging die is equal to the volume of the mold cavity under the final forging die (such as Figure 3The principle of designing the pre-forging die parting surface is shown in Figure 1. The volume of the lower mold cavity of the pre-forging die in this embodiment is 1653972.1mm by integration or with the aid of modeling software. 3 The integral calculation formula is as follows:

[0054]

[0055] The parting surface height is calculated using the above formula.

[0056] Since GH4169 has a low molding temperature and poor fluidity, the molding process relies less on the burr groove and is not easy to produce burrs. Therefore, the traditional bridge part and bin part are no longer set at the parting surface of the pre-forging die, but a residual material groove 42 is set, such as Figure 4 As shown, the residual material groove 42 is formed by connecting S-shaped structures 421 extending outward from the ends of the vertical walls of the upper die and the lower die of the pre-forging mold. The residual material groove 42 can accommodate the residual material on the one hand and prevent burrs from being formed by pre-forging on the other hand.

[0057] The arc radius R of the S-shaped structure in the residual material trough satisfies: Where V 坯料 is the original blank cutting volume, V 坯料 V is the volume of the pre-forging cavity. 坯料 =V 坯 , V 坯料 About V 型腔 0.98 to 1.02 times of.

[0058] The design of the final forging die is as follows: Figure 2 As shown, the design principle is: according to the part size provided by the part design drawing, the basic outline of the forging is obtained after adding the allowance. On this basis, while ensuring the forging forming, the existence of the forging deformation dead zone is minimized as much as possible.

[0059] The margin z is designed as: M is the minimum allowance for forging finishing, m is the maximum offset of the forging, h0 is the depth of the defect layer on the surface of the forging, and x is the lower deviation value of the forging size.

[0060] The draft angle α of the final forging die satisfies: α<arctanμ, where μ is the friction coefficient between the forging and the final forging die.

[0061] On the basis of obtaining the basic outline of the forging, considering the existence of the inner hole B in the part, the boss set on the final forging die can reduce the deformation dead zone of the forging, wherein the upper die boss 11 is an elliptical boss, such as Figure 5 As shown, the major axis a and minor axis b of the elliptical boss satisfy: d is the diameter of the inner hole B of the forging, k is the rigidity coefficient of the forging material, usually 0.8 to 1.5, the softer the material, the larger the k value, and z is the machining allowance of the forging. The lower die boss 21 is different from the upper die boss 11, and can be designed by directly adding allowance according to the part size without special design.

[0062] In order to reduce the forging transfer time of forgings, the present embodiment integrates the pre-forging die and the final forging die on the same die, that is, the die is designed as a one-die dual-cavity, and the pre-forging cavity and the final forging cavity are synchronously closed in one mold. The one-die dual-cavity design can be heated and formed in one time, ensuring that the forging has sufficient deformation in one heating, ensuring a good subsequent organizational foundation. Because the forgings will cool down quickly after leaving the furnace during forging, the forging must be completed by entering the final forging cavity before the temperature drops to the specified temperature from pre-forging to final forging, otherwise it needs to be reheated. In addition, the GH4169 hollow disk-shaft integrated forging is large in size and difficult to transfer. The one-die dual-cavity can improve the transfer efficiency, realize one-fire forming, and prevent the temperature from dropping too much during the transfer process.

[0063] It should be noted that during the forging process, the use of a double-cavity mold is as follows: a part must be processed in the pre-forging cavity and the final forging cavity in sequence before the next part can be processed.

[0064] Example 2

[0065] This embodiment describes the specific process of forging in Example 1:

[0066] 1. Cut the raw materials into Φ160×235mm specifications, chamfer and obtain the original blank.

[0067] 2. Heat the original blank in a baking oven to a certain temperature, such as 80-120°C, and then spray a layer of glass lubricant on the surface of the original blank with a spray gun, with a spray thickness of 0.3-0.5 mm.

[0068] 3. Heat the original billet to the forging temperature range of the material, such as 900°C to 1100°C, and keep it warm for a certain period of time, such as 50 to 100 minutes.

[0069] 4. Preheat the double-cavity mold to the specified material temperature, such as 250°C, and install it on the press. Place glass fiber insulation blankets in both the pre-forging cavity and the final forging cavity.

[0070] 5. Remove the heated original blank and put it into the pre-forging cavity for forging to obtain the pre-forged blank. The true strain field of pre-forging is as follows: Figure 7 shown.

[0071] 6. Place the pre-forged billet into the final forging cavity within 3 to 8 seconds to obtain the final forging. Figure 8 The true strain field after pre-forging and final forging is shown.

[0072] 7. Move the resulting forging into an oil tank for cooling.

[0073] At this point, the forging is completed, and then heat treatment and rough turning are carried out to obtain the finished parts, which are then put into storage after passing the inspection.

[0074] The present invention aims at the problem of insufficient local deformation and unqualified local microstructure grains in the blank forging process of GH4169 hollow disk-shaft integrated parts. By adding a pre-forging process, the mold is changed into a one-mold dual-cavity mold, and the pre-forging and final forging are formed by one fire. At the same time, the boss design is performed on the final forging mold to increase the deformation of the forging and avoid deformation dead zones. In addition, the forging process is optimized by increasing the mold preheating temperature, adding a glass fiber insulation blanket, and oil cooling after forging, so as to avoid the deformation of the forging at about 900°C (δ phase precipitation peak) caused by the rapid temperature drop between the forging and the mold. Compared with traditional air cooling, oil cooling after forging shortens the residence time of the forging at the precipitation peak, avoids the risk of coarse grains, mixed grains and large amounts of δ phase precipitation to form black crystal structure in the forging, effectively improves the uniformity of the forging structure, and ensures that the forging structure performance is within the technical specification range.

[0075] Comparative Example 1

[0076] In contrast to Example 1, the original billet was not pre-forged but directly final forged. The true strain field of the forging is as follows: Fig. 9 shown.

[0077] Obviously, the above embodiments are merely examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for forging a high-temperature alloy part with an inner hole, characterized in that The forging process includes pre-forging and final forging performed in sequence. The pre-forging is used to increase the strain of the forging blank before the final forging. The upper die of the final forging die is provided with a boss. The boss forms a recessed portion on the forging blank when the final forging die is closed. The boss is used to reduce the deformation dead zone of the forging.

2. The forging method of a high-temperature alloy part with an inner hole according to claim 1, characterized in that: The pre-forging cavity of the pre-forging die is designed as follows: S1. Known forging billet volume V after final forging 坯 and the total height H, and the diameter D of the original blank is obtained; Where n is the roughness ratio of the final forging head; S2. According to the original billet diameter D, design the diameter W1 of the pre-forging cavity. S3. Given the volume of the lower mold cavity of the final forging die, design the parting surface of the pre-forging die based on the principle that the volume of the lower mold cavity of the pre-forging die is equal to that of the final forging die.

3. The forging method of a high-temperature alloy part with an inner hole according to claim 2, characterized in that: Both ends of the pre-forging cavity in the height direction are conical structures, and the conical height h1 of the conical structure satisfies h1>h / 4, where h is the length of the original blank; and the conical angle A of the conical structure satisfies A<45°.

4. The forging method of a high-temperature alloy part with an inner hole according to claim 2, characterized in that: A residual material groove is provided at the parting surface of the pre-forging die, and the residual material groove is formed by connecting S-shaped structures extending outward from the ends of the vertical walls of the upper die and the lower die of the pre-forging die, respectively, and the arc radius R of the S-shaped structure satisfies: Where V 坯料 is the original blank cutting volume, V 型腔 is the volume of the pre-forging cavity.

5. The method for forging a high-temperature alloy part with an inner hole according to claim 1, characterized in that: The boss on the final forging die is an elliptical boss, and the major axis a and the minor axis b of the elliptical boss satisfy: Where d is the inner hole diameter of the forging, k is the rigidity coefficient of the forging material, and z is the machining allowance of the forging.

6. The method for forging a high-temperature alloy part with an inner hole according to claim 5, characterized in that: M is the minimum allowance for forging finishing, m is the maximum offset of the forging, h0 is the depth of the defect layer on the surface of the forging, and x is the lower deviation value of the forging size.

7. The method for forging a high-temperature alloy part with an inner hole according to claim 1, characterized in that: The draft angle α of the final forging die satisfies: α<arctanμ, where μ is the friction coefficient between the forging and the final forging die.

8. The method for forging a high-temperature alloy part with an inner hole according to claim 1, characterized in that: The pre-forging die and the final forging die are integrated on the same die, and one-time die closing can realize synchronous die closing of the pre-forging cavity and the final forging cavity.

9. The method for forging a high-temperature alloy part with an inner hole according to claim 1, characterized in that: The interval time from the end of pre-forging to the transfer of the forging into the final forging die is 3 to 8 seconds.

10. The method for forging a high-temperature alloy part with an inner hole according to claim 1, characterized in that: The pre-forging cavity of the pre-forging die and the final forging cavity of the final forging die are both padded with glass fiber insulation blankets.

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