A forming method for controlling the strength of a small ring-shaped Fe-Ni-Cr high-temperature alloy membrane forging

Abstract

The present application belongs to the field of forging hot working, and particularly relates to a forming method for controlling the strength of a Fe-Ni-Cr high-temperature alloy small ring piece by using a membrane forging. The method comprises the following steps: step 1, determining the size of a membrane and a pad according to the shape and size of a forging piece, the membrane having a columnar cavity, and the upper end surface of the pad having a circular boss; step 2, selecting a rod specification that meets the required forging ratio according to the required volume of the forging piece, and blanking according to the principle of equal volume and considering forging deviation; step 3, selecting a heating temperature corresponding to the material according to the material characteristics of the rod, and heating in an electric furnace, while preheating the membrane and the pad; step 4, assembling the preheated membrane and the pad, putting the rod into the assembled combined tooling, and forging; step 5, after the forging is completed, air cooling is performed, and after cooling to room temperature, inner hole processing is performed; and step 6, heat treating the forging piece according to a heat treatment system.

Description

Technical Field

[0001] This invention belongs to the field of forging hot working, and specifically relates to a forming method for controlling the strength of Fe-Ni-Cr high temperature alloy small ring parts by die forging. Background Technology

[0002] Fe-Ni-Cr high-temperature alloys are nickel-based precipitation-strengthened wrought superalloys. They exhibit high strength within a temperature range of -253℃ to 650℃, while requiring tensile and fatigue strength below 650℃. Simultaneously, they maintain high toughness at high temperatures, demonstrating excellent creep resistance, making them suitable for service in high-temperature environments. They are resistant to various corrosive media, including seawater, salt spray, industrial atmospheres, and some acidic and alkaline environments, and possess excellent oxidation resistance.

[0003] Aging treatment can form strengthening phases (such as the "γ" phase and γ' phase), which significantly improves the strength of the alloy and makes its microstructure less prone to change during long-term use. These properties make it widely used in aerospace, gas turbine, and nuclear industries, such as in the manufacture of key components like turbine disks and blade fasteners. Summary of the Invention

[0004] Objective of the invention: To provide a forming method for controlling the strength of Fe-Ni-Cr high-temperature alloy small ring parts by die forging, thereby improving the performance of the forgings and meeting the grain size requirements of the forgings.

[0005] Technical solution: A forming method for controlling the strength of Fe-Ni-Cr high-temperature alloy small ring parts by die forging includes: Step 1: Determine the size of the diaphragm and the pad block according to the shape and size of the forging. The diaphragm has a columnar cavity, and the upper end face of the pad block has a circular boss. Step 2: Select bar specifications that meet the required forging ratio based on the required volume of the forging, and cut the bar using the principle of equal volume and taking forging deviation into account. Step 3: Select the heating temperature corresponding to the material according to the material properties of the bar, heat it in the electric furnace, and at the same time preheat the membrane and pad block; Step 4: Assemble the preheated tire membrane and pad block, place the bar stock into the assembled tooling, and forge; Step 5: After forging, air cool the material to room temperature before machining the inner hole. Step 6: Perform heat treatment on the forgings according to the heat treatment regime.

[0006] Further, in step 1, the lower end face dimension d1 of the diaphragm cavity is the outer diameter dimension D+δ of the forging, where δ is the forging allowance of the forging; the height h of the diaphragm is the height H+μ of the forging, where μ is 2 / 3h1, and h1 is the height of the pad block.

[0007] Furthermore, the outward slope θ of the columnar cavity is 1.5° to 7.0°.

[0008] Furthermore, the diameter d2 of the upper end face of the cylindrical cavity satisfies: d2=2tgθ×h+d1.

[0009] Furthermore, the height of the pad boss is 1 / 3 of the forging height H, and the outer diameter of the pad is d1.

[0010] Furthermore, the diameter of the pad boss is 1 / 3 d1.

[0011] Furthermore, in step 3, the tooling preheating temperature is between 250℃ and 300℃, and the heat preservation time is controlled at 2 to 3 hours.

[0012] Furthermore, after the bar stock is removed from the furnace, it is covered with insulating cotton and then transferred to a forging fixture for forging.

[0013] Furthermore, during forging, a single-click method is used and the hammering frequency is controlled.

[0014] Furthermore, the forging process must ensure that the caulking cavity is completely filled, and after the cavity is filled, a height dimension under-indentation of 2-3 mm is allowed.

[0015] Beneficial effects: This application employs tooling-based die forging, combined with control of forging temperature and deformation, to meet the grain size requirements of the forgings and achieve the final desired results. Compared to conventional forging methods, this approach reduces the number of forging passes and solves the problem of insufficient or excessive deformation at each forging step, which leads to substandard grain size and scrapped forgings, resulting in significant resource waste. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the assembly of a special tooling membrane and pad blocks; Figure 2 This is a drawing of a forging. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0020] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0022] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0024] The forging of small rings typically involves six steps: upsetting, punching, reaming, end-face finishing, pre-reaming, and reaming. Using this conventional method, multiple forging passes are required, making it difficult to control the deformation amount in each pass to meet the necessary requirements. This results in the forging's final microstructure and properties failing to meet the requirements, with grain size generally reaching only 4-6 levels. It is difficult to meet the high-strength process requirement of a grain size of 8 or higher, leading to unqualified physical and chemical tests of the forging.

[0025] This application provides a method for controlling production parameters by employing effective forging temperature and deformation control, designing a special die according to the size of the forging, and using die forging to avoid the defects of conventional forging, such as multiple forging passes and insufficient or excessive deformation. The method can reduce the usual forging steps from multiple steps to a single operation.

[0026] like Figure 1 and 2 The specific steps of the high-strength Fe-Ni-Cr high-temperature alloy small ring forging method of this application are as follows: Step 1: Pre-fabricate the required special tooling 1, the die, according to the dimensions of the forging. The shape of the die is similar to that of the forging, both being ring-shaped. The diameter d1 of the lower end face of the die cavity is the outer diameter D + δ of the forging (δ is the forging allowance), and its outer diameter d3 is the designed inner diameter of the die + (2 × ε), (ε is the die wall thickness, determined according to the size and weight of the forging and the required production equipment). Its height h is the height H + μ of the forging (μ is 2 / 3h1). When machining the inner diameter of the die, a suitable draft angle θ needs to be selected according to the height of the forging, generally selected between 1.5° and 7.0°. The relationship between the lower end face dimension d1 and the upper end face diameter d2 is d2 = 2(tgθ × h) + d1; Figure 1 ; Step 2: Design a special tooling block 2 for forging on the lower end face of the forging diaphragm according to the height of the forging; the height of the boss of the special tooling block 2 is 1 / 3 of the height H of the forging; the outer diameter is the inner diameter d1 of the diaphragm of special tooling block 1; the upper end face of the special tooling block 2 is the working part, and the diameter of the working part is 1 / 3 of the inner diameter d1 of the diaphragm. ； For a forging with a height of 1 / 3 of its height H, the boss and the upper working surface should be smoothly transitioned with rounded corners to form the maximum working surface.

[0027] Step 3: Select a bar stock specification φM that meets the required conventional forging ratio based on the required volume of the forging. Determine the blanking length L of the forging by adopting the principle of equal volume and appropriately increasing the forging allowance after considering forging deviation. The principle is that the selected bar stock can be easily placed into the special tooling 1 mold and special tooling 2 pad for easy forging. Process any end of the selected bar stock. Its processing dimensions are completely symmetrical with the boss part of the special tooling 2 pad. Its function is to stand the processed end into the boss part of the special tooling 2 pad during forging. Ensure that the axis of the forging is perpendicular to the horizontal plane of forging. This prevents the forging from being misaligned during forging or the forging center from being offset from the center of the mold, resulting in local incomplete filling of the forging and uneven deformation of the forging.

[0028] Step 4: Select the heating temperature corresponding to the material according to the material characteristics of the above-mentioned required bars, and heat them in an electric furnace. At the same time, preheat the prefabricated special tooling 1 mold and special tooling 2 pad. The tooling preheating temperature is 250℃-300℃, and the heat preservation time is controlled at 2-3 hours.

[0029] Step 5: After preheating the above-mentioned special tooling 1 diaphragm and special tooling 2 pad, perform a simple assembly according to Figure 2 before forging. That is, place the special tooling 2 pad inside the inner hole of the special tooling 1 diaphragm, and ensure that the non-working surface of the special tooling 2 pad and the small end face of the inner hole of the special tooling 1 diaphragm are on the same horizontal plane. Step 6: To ensure that the forging temperature is not lost too quickly, the bar is covered with insulating cotton after it comes out of the furnace.

[0030] Step 7: Select appropriate forging equipment based on the weight and dimensions of the forging bar. To ensure the forging temperature does not drop too quickly, cover the bar with insulating cotton after it exits the furnace and transfer it to the forging fixture for forging. Before forging, ensure that one end of the processed bar is in complete contact with the working part of the special fixture pad 2, and that the bar axis is perpendicular to the horizontal plane before forging. Control the hammering frequency during forging; continuous hammering is not allowed.

[0031] Step 8: After forging, air cool the material to room temperature before machining the inner hole. Step 9: Perform heat treatment on the forgings according to the heat treatment regime.

[0032] Step 10: Conduct physical and chemical tests on the forgings. All performance indicators must meet the standards and the grain size must meet the requirements.

[0033] (Note: If cracks are found during the forging process described above, forging should be stopped immediately. After sandblasting and grinding to remove the defects, the forging process can be restarted.) The technical solution of the present invention will be further described in detail below with reference to examples: The present invention provides a method for forming Fe-Ni-Cr high-temperature alloy ring forgings. By employing a tooling-based die forging method, the forging temperature and deformation are effectively protected, thereby controlling the forging process to meet the grain size requirements of the forgings and achieving the final desired forging specifications.

[0034] The following is a specific embodiment: The support blank forging of the present invention has forging dimensions of φ195×φ105×78; material: high-strength Fe-Ni-Cr high temperature, category II; process specification requires blanking size of φ150×170; weight: 24.75Kg; the overall performance indicators and grain size requirements of the forging shall meet the requirements of Q / S10-0514-2004 standard (grain size requirement level 8).

[0035] The forging process is detailed below: Step 1: After cutting the bar stock (φ150×170mm), chamfer the corner of one end of the bar stock with an edge of R5; then process the other end of the bar stock by stacking the boss part of the special pad block.

[0036] Step 2: After the billet is processed, it is put into the electric furnace at 1000℃ and heated to 1000℃. The high temperature holding time is 120 minutes, and then it is taken out of the furnace for forging (completed in 1 fire). Step 3: After preheating, assemble the prefabricated special tooling 1 (moon film) and special tooling 2 (pad block) before forging. Place the pad block 2 into the inner hole of the tooling 1 (moon film), ensuring that the tooling part of the pad block faces upward and is aligned with the upward direction of the maximum inner diameter of the moon film.

[0037] Step 4: When processing the heated and insulated billet, cover it with insulating cotton and quickly transfer it into the forging fixture mold. Ensure that the machined concave end face of the bar and the pad block 2 are in complete perpendicular contact before starting forging. Control the hammering frequency during forging. Ensure the mold cavity is completely filled. After ensuring the cavity is filled, a height under-pressure of 2-3mm is permissible. Step 5: After forging, the forging is easily removed by using a manipulator to invert the upper and lower end faces of the die. After marking, it is air-cooled. The outer diameter and height of the forging are measured to ensure that the final part meets the processing requirements.

[0038] Step 6: Before heating, rough machine the inner hole to φ95; and chamfer the upper and lower end faces of the inner hole to R2; blow sand and grind.

[0039] Step 7: Perform heat treatment on the forgings according to the heat treatment specifications; Step 8: Conduct physical and chemical tests on the forgings. All performance indicators must meet the standards and the grain size must meet the requirements.

[0040] The grain size of Fe-Ni-Cr high-temperature alloy ring forgings is sensitive to temperature and deformation. Through production verification, this invention solves the problem of alloy grain size in Fe-Ni-Cr high-temperature alloy ring forgings with different grain size requirements by strictly controlling the deformation temperature and deformation between forging cycles.

[0041] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A forming method for controlling the strength of Fe-Ni-Cr high-temperature alloy small ring parts by die forging, characterized in that, include: Step 1: Determine the size of the diaphragm and the pad block according to the shape and size of the forging. The diaphragm has a columnar cavity, and the upper end face of the pad block has a circular boss. Step 2: Select bar specifications that meet the required forging ratio based on the required volume of the forging, and cut the bar using the principle of equal volume and taking forging deviation into account. Step 3: Select the heating temperature corresponding to the material according to the material properties of the bar, heat it in the electric furnace, and at the same time preheat the membrane and pad block; Step 4: Assemble the preheated tire membrane and pad block, place the bar stock into the assembled tooling, and forge; Step 5: After forging, air cool the material to room temperature before machining the inner hole. Step 6: Perform heat treatment on the forgings according to the heat treatment regime.

2. The method according to claim 1, characterized in that, In step 1, the lower end face dimension d1 of the diaphragm cavity is the outer diameter dimension D+δ of the forging, where δ is the forging allowance of the forging; the height h of the diaphragm is the height H+μ of the forging, where μ is 2 / 3h1, and h1 is the height of the pad block.

3. The method according to claim 1, characterized in that, The outward slope θ of the cylindrical cavity is 1.5° to 7.0°.

4. The method according to claim 1, characterized in that, The diameter d2 of the upper end face of the cylindrical cavity satisfies: d2=2tgθ×h+d1.

5. The method according to claim 1, characterized in that, The height of the boss on the pad block is 1 / 3 of the height H of the forging, and the outer diameter of the pad block is d1.

6. The method according to claim 1, characterized in that, The diameter of the boss on the pad is 1 / 3 d1.

7. The method according to claim 1, characterized in that, In step 3, the tooling preheating temperature is 250℃-300℃, and the heat preservation time is controlled at 2-3 hours.

8. The method according to claim 1, characterized in that, After the bar stock is removed from the furnace, it is covered with insulating cotton and then transferred to the forging fixture for forging.

9. The method according to claim 1, characterized in that, During forging, a single-shot method is used, and the hammering frequency is controlled.

10. The method according to claim 1, characterized in that, Forging must ensure that the mold cavity is completely filled, and after filling the cavity, a height dimension under-indentation of 2-3mm is allowed.

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