A method of forging a high temperature alloy part with a bore

Abstract

The application discloses a forging method for a high-temperature alloy part with a hole, and the forging process comprises pre-forging and final forging which are sequentially performed, the pre-forging is used for increasing the strain of a forging blank before the final forging, an upper die of a final forging die is provided with a boss, the boss forms a recess on the forging blank when the final forging die is closed, and the boss is used for reducing a deformation dead zone of a forged piece. The boss is designed on the final forging die, the forging process is divided into two stages of pre-forging and final forging, the deformation of the blank is increased through the pre-forging before the final forging, and the subsequent deformation is more uniform; the pre-forging and the final forging are combined with the boss design on the final forging die, and the boss design on the final forging die plays a role together, so that the effect of eliminating the deformation dead zone of the forged piece is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of part forging, in particular to a high-temperature alloy part forging method with a hole. BACKGROUND

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

[0003] The excellent strength performance of GH4169 high-temperature alloy is closely related to its internal microstructure. For example, for a high-quality GH4169 disc-shaft integrated part of an aero-engine, the most important condition for ensuring that the forged part meets the use requirements is the distribution of δ phase, as well as the grain size and uniformity. In theory, the δ phase should be uniformly distributed in the form of granular or short rod. Due to the particularity of the working position, the grain size of the forged part should be uniform, and the grain size level should not be less than 8 levels.

[0004] However, in the actual forging process, whether it is free forging or die forging, it is difficult to avoid the occurrence of insufficient deformation area in the forming process, which is commonly known as "deformation dead zone". The larger the forged part, the more difficult the deformation, that is, the larger the "deformation dead zone". The "deformation dead zone" will lead to problems such as coarse grain structure. In addition, improper handling during the forging process may also cause the appearance of "black crystal" structure in the forged part, which is not allowed.

[0005] The traditional forging process of a high-quality GH4169 hollow disc-shaft integrated part (such as Figure 1 ) is die forging on a screw press (such as Figure 10 ). The forged part is shown in Figure 11 . When detecting the high-magnification structure, coarse grains, mixed grains and "black crystal phenomenon" appear at positions a and b of the forged part, as shown in Figure 12 and Figure 13 , which directly leads to the determination of the forged part as unqualified.

[0006] It is found through analysis that the positions a and b are in the deformation dead zone, and εtrue is only 0.02 ( Figure 14 ), almost no deformation.

[0007] The patent with the publication number CN114535484A discloses a die for improving the deformation dead zone of a large-size disc forging and a blanking process. The die includes an upper die and a lower die. 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. The spherical crown-shaped upper protrusion and the spherical crown-shaped lower protrusion are oppositely arranged. The blanking process includes the following steps: S1: a workpiece is subjected to primary blanking to obtain a primary forging; the primary forging is subjected to secondary blanking to obtain a secondary forging; the secondary forging is subjected to die forging to obtain a disc forging; S2: an alloy database is constructed by using the Arrhenius equation; and S3: a finite element simulation is performed on the forging process.

[0008] Although the above-mentioned patent mentions that its die can effectively reduce the generation of workpiece end face deformation dead zone and is beneficial to the control of disc forging end face grain structure. However, it is found through practice that the measure of arranging protrusions on the die is not enough to completely avoid the deformation dead zone. Therefore, how to further design the forging die or the forging process so as to truly overcome the problem of deformation dead zone and even the problem of coarse grain and black grain is a difficult problem in the industry at present. SUMMARY

[0009] The technical problem to be solved by the present application is to provide a high-temperature alloy part forging method with a hole, which can effectively avoid deformation dead zone and ensure that the structure and performance of the forged part meet the technical requirements.

[0010] The object of the present application is achieved by the following technical solutions.

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

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

[0013] S1. Knowing the volume V of the forging blank after finish-forging, 坯 and the total height H, the diameter D of the original blank is obtained; wherein n is the finish-forging reduction ratio;

[0014] S2. According to the diameter D of the original blank, the diameter W1 of the pre-forging cavity is designed,

[0015] S3. Knowing the volume of the lower die cavity of the finish-forging die, the parting surface of the pre-forging die is designed according to the principle that the volume of the lower die cavity of the pre-forging die is equal to the volume of the lower die cavity of the finish-forging die.

[0016] Further, the pre-forging cavity is provided with a taper structure at both ends along the height direction, the taper height h1 of the taper structure satisfies h1>h / 4, h is the length of the original blank, and the taper angle A of the taper structure satisfies A<45°.

[0017] Further, the pre-forging die is provided with a surplus material groove at the parting surface, the surplus material groove is connected by S-shaped structures which are extended outward from the ends of the vertical walls of the upper die and the lower die of the pre-forging die, and the arc radius R of the S-shaped structure satisfies: Wherein, V 坯料 is the blanking volume of the original blank, V 型腔 is the volume of the pre-forging cavity.

[0018] Further, the boss on the finish-forging die is an elliptical boss, the long axis a and the short axis b of the elliptical boss satisfy: Wherein, d is the inner hole diameter of the forged piece, k is the rigidity coefficient of the forged piece material, and z is the machining allowance of the forged piece.

[0019] Further, M is the minimum allowance of the finish-forging of the forged piece, m is the maximum displacement of the forged piece, h0 is the depth of the surface defect layer of the forged piece, and x is the lower deviation value of the size of the forged piece.

[0020] Further, the ejection slope a of the finish-forging die satisfies a<arctan mu, mu is the friction coefficient between the forged piece and the finish-forging die.

[0021] Further, the pre-forging die and the finish-forging die are integrated on the same die, and the pre-forging cavity and the finish-forging cavity can be synchronously clamped by one clamping.

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

[0023] 1) The present application designs a boss on the finish-forging die, divides the forging process into two stages of pre-forging and finish-forging, increases the deformation of the blank through pre-forging before finish-forging, and makes the subsequent deformation more uniform; the pre-forging and the finish-forging steps combine with the boss design on the finish-forging die to play a role together, and eliminate the deformation dead zone of the forged piece.

[0024] 2) The integrated design of the pre-forging and the finish-forging die "one die with double cavities" can realize the one-heat forming of pre-forging and finish-forging, so that the forged piece has enough deformation in one heating, and the transfer time and the heating times are reduced.

[0025] 3) The forging process is optimized by increasing the preheating temperature of the die, adding a glass fiber heat preservation blanket in the die cavity, and oil cooling after forging, so as to improve the uniformity of the forged piece, avoid the problems of coarse grains and black crystals, mixed crystals, and ensure that the organization performance of the forged piece meets the technical requirements. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 This is a schematic diagram of the GH4169 integrated disc shaft component described in Embodiment 1 of the present invention;

[0027] Figure 2 This is a cross-sectional view of the pre-forging cavity and the final forging cavity in the integrated mold described in Embodiment 1 of the present invention;

[0028] Figure 3 This 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 as described in Embodiment 1 of the present invention;

[0029] Figure 4 for Figure 2 Cross-sectional view of the intermediate residue trough;

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

[0031] Figure 6 This is a schematic diagram of the original billet structure described in Embodiment 2 of the present invention;

[0032] Figure 7 This refers to the true strain field of the pre-forging process described in Embodiment 2 of the present invention;

[0033] Figure 8 This is the true strain field after pre-forging and final forging as described in Embodiment 2 of the present invention;

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

[0035] Figure 10 A schematic diagram of the traditional forging process for the GH4169 hollow disc shaft integral component;

[0036] Figure 11 for Figure 9 A schematic diagram of the forging structure obtained by the forging process shown;

[0037] Figure 12 for Figure 11 Black grain and coarse grain phenomena at positions a and b of the forging;

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

[0039] Figure 14 for Figure 9 True strain field during the forging process. Detailed Implementation

[0040] To clearly illustrate the technical features of this solution, the following detailed description, in conjunction with the accompanying drawings, will explain the technical solution in detail.

[0041] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced without the specific details. In other instances, well-known methods have not been described in detail in order not to unnecessarily obscure aspects of the present application.

[0042] In addition, in the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like are intended to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplification of description, and do not indicate or imply that the device or element indicated thereby must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated thereby. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "plurality" is two or more, unless otherwise explicitly specified and limited.

[0043] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection, or communication; can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. In the description of the present application, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0045] Embodiment 1

[0046] The present embodiment provides a kind of asFigure 1 The forging method for the blank of the GH4169 hollow disc shaft integral part shown includes designing the forging die and determining the blank volume and height-to-diameter ratio based on the part shape. The forging process is divided into two stages, including pre-forging and final forging performed sequentially. Pre-forging is used to increase the deformation of the forging blank before final forging. After pre-forging, the strain increases and the deformation becomes 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. The bosses form a recess 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 dead zone of forging deformation. 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, such as Figure 2 As shown, the design is as follows:

[0048] S1. Calculate the specifications of the original billet 3: The original billet is as follows: Figure 6 As shown, the volume V of the forged billet (i.e., the forging referred to below) after final forging is known. 坯 Calculate the diameter D of the original billet 3 by combining the total height H; Where n is the final forging roughing ratio;

[0049] The length h of the original blank 3 can be calculated using the cylinder volume formula based on the diameter D mentioned above.

[0050] This embodiment determines the forging volume V based on the final forging shape design and through volume calculation or simulation methods. 坯 =3924548.6mm 3 Therefore, the original billet diameter D = 153mm and the length h = 230mm, and the final original billet specification is set as Φ160×235mm.

[0051] S2. Design of pre-forging cavity 4: In order to further avoid the deformation dead zone after the upper and lower end faces of the billet are formed during the forging process, it is preferable 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. Its relevant parameters meet the following conditions, which can make the deformation of the original billet 3 after pre-forging greater than 20%, laying a good foundation for subsequent final forging.

[0052] The relevant parameters are: the diameter of the pre-forging cavity 4. The cone height h1 of the conical structure 41 satisfies h1 > h / 4; the cone angle A of the conical structure 41 satisfies A < 45°. Based on the aforementioned specific data, the maximum diameter W1 of the pre-forging cavity is taken as 160 mm, the cone angle A as 40°, and the cone height h1 as 58 mm.

[0053] S3. Parting Surface Design: Given the volume of the lower mold cavity of the final forging die, based on the principle that the volume of the lower mold cavity of the pre-forging die is equal to the volume of the lower mold cavity of the final forging die (e.g., ... Figure 3Following the principle shown, the parting surface of the pre-forging mold is designed through integration or with the aid of modeling software. In this embodiment, the volume of the lower mold cavity of the pre-forging mold is 1653972.1 mm². 3 The formula for calculating integrals is as follows:

[0054]

[0055] The parting line height can be calculated using the above formula.

[0056] Because GH4169 has a low molding temperature and poor fluidity, the molding process relies less on the burr groove and is less prone to burr generation. Therefore, the traditional bridge and storage sections are no longer provided at the parting surface of the pre-forging die; instead, a material overflow groove 42 is provided. Figure 4 As shown, the scrap groove 42 is formed by connecting S-shaped structures 421 that extend outward from the ends of the vertical walls of the upper and lower molds of the pre-forging die. The scrap groove 42 accommodates scrap material on the one hand and avoids burrs from forming during pre-forging on the other.

[0057] The radius R of the arc of the S-shaped structure in the waste material trough satisfies: Where V 坯料 V represents the original blank cutting volume. 坯料 V represents the volume of the pre-forged cavity. 坯料 =V 坯 V 坯料 Approximately V 型腔 0.98 to 1.02 times.

[0058] Design of final forging die, such as Figure 2 As shown, the design principle is: based on the part dimensions provided by the part design drawing, the basic outline of the forging is obtained after adding the allowance. On this basis, while ensuring the forming of the forging, the existence of the forging dead zone is minimized as much as possible.

[0059] The margin z is designed as follows: M is the minimum allowance for finishing the forging, m is the maximum misalignment 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 coefficient of friction between the forging and the final forging die.

[0061] Based on the basic outline of the forging, and considering the presence of an inner hole B, the boss on the final forging die can reduce the dead zone of the forging deformation. The upper die boss 11 is an elliptical boss. Figure 5 As shown, the major axis a and minor axis b of the elliptical boss satisfy: d is the diameter of the hole B of the forging, k is the rigidity coefficient of the forging material, usually 0.8-1.5, the softer the material, the greater the value of k, and z is the processing allowance of the forging. The upper die boss 11 and the lower die boss 21 are different, and only need to be designed according to the size of the part directly plus the allowance, without special design.

[0062] In order to reduce the forging transfer time, the pre-forging die and the finish-forging die are integrated on the same die in the embodiment, that is, the die is designed as a one-die double-cavity, and the pre-forging cavity and the finish-forging cavity are synchronously clamped once. The one-die double-cavity design can be formed once heating, which ensures that the forging has enough deformation in one heating and ensures good organization foundation in the follow-up. Because the forging is quickly cooled after being taken out of the furnace during forging, the pre-forging must be completed in the finish-forging cavity before the temperature drops to the specified temperature, otherwise it needs to be reheated. In addition, the GH4169 hollow disc shaft integrated forging has a large size, and it is difficult to transfer. The one-die double-cavity can improve the transfer efficiency and realize one-fire forming to prevent the temperature from dropping too much during the transfer process.

[0063] It should be noted that during the forging process, the one-die double-cavity die is used as follows: one part is processed in the pre-forging cavity and the finish-forging cavity in turn, and then the next part is processed.

[0064] Embodiment 2

[0065] The embodiment illustrates the specific process of the forging in embodiment 1:

[0066] 1. Cutting, cutting the raw material according to the Φ160x235mm specification, chamfering, and obtaining the original blank.

[0067] 2. Heat the original blank in the oven to a certain temperature, for example 80-120℃, and then spray a layer of glass lubricant on the surface of the original blank with a spray gun, with a spraying thickness of 0.3-0.5mm.

[0068] 3. Heat the original blank to the forging temperature range of the material, for example 900-1100℃, and keep it for a certain time, such as 50-100min.

[0069] 4. Preheat the one-die double-cavity die to the specified temperature of the material, such as 250℃, and install it on the press, and pad the glass fiber insulation blanket in the pre-forging cavity and the finish-forging cavity.

[0070] 5. Put the heated original blank into the pre-forging cavity to forge, and obtain the pre-forging blank. The true strain field of pre-forging is shown in Figure 7 .

[0071] 6. Put the pre-forging formed pre-forging blank into the finish-forging cavity within 3-8s to forge, and obtain the final forging. Figure 8 The true strain field of pre-forging and then finish-forging is shown.

[0072] 7. The resulting forging is moved into an oil tank for cooling.

[0073] At this point, the forging is formed into a shape, and subsequent heat treatment, rough turning is performed to obtain a finished part, which is stored in the warehouse after passing the inspection.

[0074] The present application is aimed at the problem of insufficient local deformation and unqualified local grain structure in the forming process of the blank forging of the GH4169 hollow disc shaft integrated piece, by increasing the pre-forging process, changing the die to a double-cavity die, pre-forging and finish-forging forming at one time, and designing a boss on the finish-forging die to increase the deformation of the forging and avoid the deformation dead zone. In addition, the forging process is optimized by increasing the preheating temperature of the die, adding a glass fiber heat preservation blanket, and oil cooling after forging, so as to avoid the rapid temperature drop of the forging caused by the contact between the forging and the die, which leads to the deformation of the forging at about 900 DEG C (delta phase precipitation peak), and the oil cooling after forging shortens the residence time of the forging at the precipitation peak compared with the traditional air cooling, thereby avoiding the risk of coarse grain, mixed grain and large amount of delta phase precipitation to form black crystal structure, effectively improving the uniformity of the forging structure, and ensuring that the forging structure performance is within the technical specified range.

[0075] Comparative Example 1

[0076] This example is compared with Example 1, the original blank is not pre-forged, but directly finish-forged, and the true strain field of the forging is as shown in Figure 9 .

[0077] Obviously, the above examples are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, other different forms of changes or modifications can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A forging method for high-temperature alloy parts with internal holes, characterized in that, The forging process includes pre-forging and final forging performed sequentially. Pre-forging increases the strain of the forging blank before final forging. The upper die of the final forging die is equipped with a boss, which creates a recess in the forging blank when the final forging die is closed. This boss reduces the dead zone of the forging deformation. The boss on the final forging die is an elliptical boss, and the major axis a and minor axis b of the elliptical boss satisfy the following: , where d is the inner diameter of the forging, k is the rigidity coefficient of the forging material, and z is the machining allowance of the forging.

2. The forging method for high-temperature alloy parts with internal holes according to claim 1, characterized in that, The pre-forging cavity design of the pre-forging die is as follows: S1. Given the volume of the forged billet after final forging. V 坯 Total H The diameter of the original billet is obtained. D ; D ,in n For the final forging roughing ratio; S2. Based on the original billet diameter D Design the diameter of the pre-forging cavity W 1, W 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 the volume of the lower mold cavity of the final forging die.

3. The forging method for high-temperature alloy parts with internal holes according to claim 2, characterized in that, The pre-forging cavity has conical structures at both ends along its height direction, and the height of the conical structure is... h 1. Satisfy h 1> h / 4, h The length of the original blank; the cone angle of the conical structure. A satisfy A < 45°.

4. The forging method for high-temperature alloy parts with internal holes according to claim 2, characterized in that, A material retention groove is provided at the parting surface of the pre-forging die. The material retention groove is formed by connecting S-shaped structures extending outward from the ends of the vertical walls of the upper and lower dies of the pre-forging die, respectively. The arc radius of the S-shaped structure is... R satisfy: R ,in V 坯料 This represents the original blank cutting volume. V 型腔 This refers to the volume of the pre-forged cavity.

5. The forging method for high-temperature alloy parts with internal holes according to claim 1, characterized in that, z = M + m + h 0 + ， M This is the minimum allowance for finishing the forging. m The maximum displacement of the forging. h 0 represents the depth of the defect layer on the surface of the forging. x This represents the lower deviation value of the forging dimensions.

6. The forging method for high-temperature alloy parts with internal holes according to claim 1, characterized in that, Draft angle of final forging die α satisfy: α < arctan μ , μ It is the coefficient of friction between the forging and the final forging die.

7. The forging method for high-temperature alloy parts with internal holes according to claim 1, characterized in that, The pre-forging mold and the final forging mold are integrated on the same mold, and the pre-forging cavity and the final forging cavity can be closed synchronously in one mold closing.

8. The forging method for high-temperature alloy parts with internal holes according to claim 1, characterized in that, The interval between the end of pre-forging and the transfer of the forging to the final forging die is 3 to 8 seconds.

9. The forging method for high-temperature alloy parts with internal holes according to claim 1, characterized in that, Both the pre-forging cavity of the pre-forging mold and the final forging cavity of the final forging mold are lined with glass fiber insulation blankets.

Images