Method for controlling uniformity of large-size complex variable cross-section high-temperature alloy forging structure

Abstract

The application provides a control method for uniformity of a large-size complex variable cross-section high-temperature alloy forging structure, and comprises the following steps: S1, matching design is performed on a pre-forging die and a final forging die, and a metal flow space is designed through DEFORM software; S2, according to a shape structure of a pre-forging piece, a temperature distribution result of numerical simulation is combined; S3, after the forging piece is heated to 1000-1020 DEG C, it is discharged, wrapped with insulation cotton, and transported to the die within 100s; S4, when final forging is performed, the forging piece is self-adaptingly constrained and accurately positioned through a matching inclined surface of the pre-forging piece and the final forging die and a bottom contact surface of the pre-forging piece and the final forging die; S5, after the forging piece is positioned, forging is performed, the bottom small cross-section part is deformed first, the speed is pressed to 12-15mm / s, and then the speed is pressed to 10mm / s until the end. Through numerical simulation iteration, the size of the pre-forging piece is matched and designed, a final forging piece with good deformation is obtained, and thus a large-size variable cross-section high-temperature alloy forging piece with uniform structure and excellent performance is obtained.

Description

Technical Field

[0001] This invention relates to the field of machining technology, and in particular to a method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forgings. Background Technology

[0002] High-temperature alloy forgings are mostly used in low-pressure turbine disks, high-pressure turbine disks, high-pressure compressor disks and their transition parts in engines. Forgings are subjected to complex stresses at high temperatures and in harsh working environments, which places high demands on the microstructure and properties of the forgings.

[0003] The large differences in the microstructure of forgings make them prone to microstructural stress, which can lead to stress concentration, causing forging failure and resulting in major quality and safety accidents.

[0004] When high-temperature alloy forgings are formed using ordinary forging (die temperature less than 600℃), cold die structure is easily generated. This coarse cold die structure or mixed grain structure is caused by insufficient recrystallization of the forging. The recrystallization process of the forging is closely related to the forging temperature, deformation amount, and deformation rate during the forging process.

[0005] Traditional high-temperature alloy forgings of disc and shaft types have relatively small cross-sectional differences and can be formed using conventional upsetting and die forging methods, achieving good microstructure and property matching. For small variable cross-section high-temperature alloy forgings, adding process auxiliary materials, i.e., appropriately increasing machining allowance during forging design, can also achieve uniform microstructure control. However, for large-sized complex variable cross-section high-temperature alloy forgings, adding process auxiliary materials will inevitably lead to a sharp increase in cost. If the traditional upsetting and die forging process is used, it is easy to cause uneven local deformation of the forging. The deformation is large and the temperature dissipates quickly in the thin section (about 40mm thick), while the temperature dissipates slowly but the deformation is small in the rear section (about 150mm thick), thus failing to obtain a uniform microstructure. Currently, there are few reports on the forming and microstructure uniformity control of large-sized complex variable cross-section high-temperature alloy forgings. In order to improve the overall performance level of engines, breakthroughs are urgently needed in the forming and microstructure uniformity control technology of such large-sized complex variable cross-section high-temperature alloy forgings. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forgings. Through numerical simulation iteration, the size of the pre-forging part is matched and designed to obtain a final forging with good deformation. During the production process, the temperature of the forging is controlled by an appropriate method, thereby obtaining a large-size variable cross-section high-temperature alloy forging with uniform microstructure and excellent performance.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] A method for controlling the uniformity of microstructure in large-size, complex variable cross-section superalloy forgings includes the following steps:

[0009] S1. Match the pre-forging die and the final forging die, and design the metal flow space using DEFORM software to ensure that the deformation of each section of the part body is ≥15% during final forging, while ensuring good positioning during final forging.

[0010] S2. Based on the shape and structure of the pre-forged part and combined with the temperature distribution results of the numerical simulation, cover the bottom of the pre-forged part and the location of the largest outer circle small cross-section deformation with an extra layer of insulation cotton.

[0011] S3. Upsetting: After the forging is heated to 1000-1020℃, it is taken out of the furnace, wrapped with heat insulation cotton, and transferred to the mold for upsetting within 100s to upset the forging into a cake blank.

[0012] S4. Pre-forging: The upset billet is placed into a pre-forging mold and pressed into a pre-forging part (the billet for final forging);

[0013] S5. Final forging: The pre-forging part is forged and deformed by the final forging die. During the final forging, the forging part is adaptively constrained and accurately positioned by the matching inclined surface between the pre-forging part and the final forging die and the bottom contact surface between the pre-forging part and the final forging die.

[0014] S6. After the forging is self-adaptively positioned by the final forging die, it is forged. The small section at the bottom is deformed first, and the pressing speed is 12-15 mm / s. When the thickness of the small section of the blank increases to more than 80 mm, the pressing speed is 5 mm / s. When the upper die of the final forging die contacts the maximum outer circle of the pre-forged blank, it is pressed at a speed of 10 mm / s until the end.

[0015] In step S1, the matching design includes forging structure optimization design, pre-forging design, final forging design, and final forging preparation.

[0016] In step S2, the thickness of the largest outer circular small cross section is less than 60mm.

[0017] In step S3, the insulation cotton is 10mm thick. After being wrapped, it ensures that the temperature during the forging process is greater than 990℃, thus meeting the recrystallization requirements.

[0018] In step S3, after the forging is transported to the mold, it is upset to 450-550mm at a speed of 10-12mm / s.

[0019] In step S5, the adaptive constraint and accurate positioning are achieved by using a clamping trolley to transfer the forging to the top of the final forging die. The forging can automatically slide into the cavity of the final forging die by its own weight.

[0020] In step S6, the thickness of the bottom small cross-section is less than 60mm.

[0021] The large-sized complex variable cross-section has a diameter of Φ1130mm and a height of 354mm.

[0022] The forgings require heating during upsetting, pre-forging, and final forging. The heating temperature during upsetting and pre-forging is 3-5°C lower than the heating temperature during final forging.

[0023] The beneficial effects of this invention are:

[0024] 1. Based on the structural characteristics of the part, the blank drawing of the forging is first designed according to the shape. The final forging die is designed by repeatedly optimizing it using numerical simulation technology. The size of the pre-forging part is matched by numerical simulation iteration to obtain a final forging with good deformation. The temperature of the forging is controlled by appropriate methods during the production process, thereby obtaining a large-size variable cross-section high-temperature alloy forging with uniform structure and excellent performance.

[0025] 2. In the design of pre-forgings and forgings, the cross-sectional thickness was specified, meaning that the pre-forgings were designed to match the final forgings. This ensures that the deformation is ≥15%. Under this condition, the thin cross-section needs to deform rapidly, so the pressing speed is 12-15 mm / s. As deformation progresses, the original thin cross-section will undergo upsetting deformation, increasing the cross-section. At this point, the forging deformation heat increases, so the pressing speed needs to be reduced to prevent the forging temperature from rising excessively. Excessive temperature rise will cause grain growth and uneven microstructure. Finally, 10 mm / s is used because the die in the final forging contacts the thin cross-section of the largest outer circle of the billet, meaning that the thin cross-section begins to deform. However, the cross-sectional thickness at this location is slightly thicker than that at the bottom of the billet, so the deformation speed is set to 10 mm / s. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the pre-forging mold cavity (i.e., the outline of the pre-forging part);

[0027] Figure 2 The deformation diagram of the final forging;

[0028] Figure 3 This is a temperature field distribution diagram of the pre-forged part;

[0029] Figure 4 This is a temperature field distribution diagram of the final forging.

[0030] Figure 5 This is a schematic diagram of the final forging positioning.

[0031] Figure 6 This is a schematic diagram of upsetting.

[0032] Figure 7 This is a schematic diagram of the forging process from bar stock to billet.

[0033] Figure 8This is a schematic diagram of a large-sized, complex variable cross-section.

[0034] Figure 9 This is a schematic diagram of the grain size results for the forging. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Example 1

[0037] A method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging includes the following steps:

[0038] S1, such as Figure 1 As shown, the pre-forging die and final forging die are designed to match, and the metal flow space is designed using DEFORM software, such as... Figure 2 As shown, ensure that the deformation of each section of the part body is ≥15% during final forging, and at the same time ensure good positioning during final forging;

[0039] S2, such as Figures 3 to 4 As shown, based on the shape and structure of the pre-forged part and the temperature distribution results of the numerical simulation, an extra layer of heat insulation cotton is applied to the bottom of the pre-forged part and the location of the largest outer diameter small cross-section deformation to reduce temperature drop and reserve temperature for recrystallization.

[0040] S3. Upsetting: After the forging is heated to 1000-1020℃, it is taken out of the furnace, wrapped with heat insulation cotton, and transferred to the mold for upsetting within 100s to upset the forging into a cake blank.

[0041] S4. Pre-forging: The upset billet is placed into a pre-forging mold and pressed into a pre-forging part (the billet for final forging);

[0042] S5, such as Figure 5 As shown, final forging involves forging and deforming the pre-forging part using a final forging die. During final forging, the forging part achieves adaptive constraint and accurate positioning through the matching inclined surface between the pre-forging part and the final forging die and the bottom contact surface between the pre-forging part and the final forging die.

[0043] S6, such as Figures 6 to 7 As shown, the forging is forged after the final forging die is self-adaptively positioned. The bottom small section is deformed first, and the pressing speed is 12-15 mm / s. The thickness of the small section of the blank under the die increases to more than 80 mm, and the pressing speed is 5 mm / s. When the upper die of the final forging die contacts the maximum outer circle of the pre-forged blank, it is pressed at a speed of 10 mm / s until the end.

[0044] In the design of pre-forgings and forgings, the cross-sectional thickness is specified, meaning that the pre-forging is designed to match the final forging. This ensures that the deformation is ≥15%. Under this condition, the thin cross-section needs to deform rapidly, so the pressing speed is 12-15 mm / s. As deformation progresses, the original thin cross-section will undergo upsetting deformation, increasing the cross-section. At this point, the forging deformation heat increases, so the pressing speed needs to be reduced to prevent the forging temperature from rising excessively. Excessive temperature rise will cause grain growth and uneven microstructure. Finally, 10 mm / s is used because the die in the final forging contacts the thin cross-section of the largest outer circle of the billet, meaning that the thin cross-section begins to deform. However, the cross-sectional thickness at this location is slightly thicker than that at the bottom of the billet, so the deformation speed is set to 10 mm / s.

[0045] In step S1, the matching design includes forging structure optimization design, pre-forging design, final forging design, and final forging preparation.

[0046] In step S2, the thickness of the largest outer circular small cross section is less than 60mm.

[0047] In step S3, the thickness of the insulation cotton is 10mm. After being wrapped, it ensures that the temperature during the forging process is greater than 990℃, thus meeting the recrystallization requirements.

[0048] The recrystallization process of high-temperature alloys requires temperature, deformation amount, and deformation rate. At this temperature, a temperature greater than 990℃ can effectively ensure the smooth progress of the recrystallization process.

[0049] In step S3, after the forging is transported to the mold, it is upset to 450-550mm at a speed of 10-12mm / s.

[0050] In step S5, the adaptive constraint and accurate positioning are achieved by using a clamping trolley to transfer the forging to the top of the final forging die. The forging can automatically slide into the cavity of the final forging die by its own weight (900Kg).

[0051] In step S6, the thickness of the bottom small cross-section is less than 60mm.

[0052] like Figure 8 As shown, the diameter of the large-sized complex variable cross-section is Φ1130mm and the height is 354mm.

[0053] The forgings require heating during upsetting, pre-forging, and final forging. The heating temperature during upsetting and pre-forging is 3-5°C lower than the heating temperature during final forging.

[0054] The forging process involves sequentially upsetting, pre-forging, and final forging of a φ300 bar to finally complete the forging shape. The upsetting and pre-forging processes are more complex than the final forging process. Appropriately increasing the temperature by 3-5℃ can help reduce undesirable structures. Local undesirable structures can also be improved through recrystallization during the final forging stage.

[0055] Based on the structural characteristics of the part, a forging blank drawing was first designed conformally. Numerical simulation technology was used for repeated optimization to design the final forging die. Numerical simulation iterations were then used to match the dimensions of the pre-forging, resulting in a final forging with good deformation. During production, appropriate methods were employed to control the forging temperature, such as... Figure 9 As shown, this method yields large-size variable cross-section high-temperature alloy forgings with uniform microstructure and excellent performance.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the uniformity of microstructure in large-size, complex variable cross-section high-temperature alloy forgings, characterized by: Includes the following steps: S1. Match the pre-forging die and the final forging die, and design the metal flow space using DEFORM software to ensure that the deformation of each section of the part body is ≥15% during final forging, while ensuring good positioning during final forging. S2. Based on the shape and structure of the pre-forged part and combined with the temperature distribution results of the numerical simulation, cover the bottom of the pre-forged part and the location of the largest outer circle small cross-section deformation with an extra layer of insulation cotton. S3. Upsetting: After the forging is heated to 1000~1020℃, it is taken out of the furnace, wrapped with heat insulation cotton, and transferred to the mold for upsetting within 100s to upset the forging into a cake blank. S4. Pre-forging: The upset billet is placed into a pre-forging mold and pressed into a pre-forging part; S5. Final forging: The pre-forging part is forged and deformed by the final forging die. During the final forging, the forging part is adaptively constrained and accurately positioned by the matching inclined surface between the pre-forging part and the final forging die and the bottom contact surface between the pre-forging part and the final forging die. S6. After the forging is self-adaptively positioned by the final forging die, the forging is pressed. The small section at the bottom is deformed first, and the pressing speed is 12~15mm / s. When the thickness of the small section of the blank increases to more than 80mm, the pressing speed is 5mm / s. When the upper die of the final forging die contacts the maximum outer circle of the pre-forged blank, the pressing speed is 10mm / s until the end. The forgings require heating during upsetting, pre-forging, and final forging.

2. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: In step S1, the matching design includes forging structure optimization design, pre-forging design, final forging design, and final forging preparation.

3. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: In step S2, the thickness of the largest outer circular small cross section is less than 60mm.

4. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: In step S3, the insulation cotton is 10mm thick. After being wrapped, it ensures that the temperature during the forging process is greater than 990℃, thus meeting the recrystallization requirements.

5. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: In step S3, after the forging is transported to the mold, it is upset to 450-550mm at a speed of 10~12mm / s.

6. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: In step S5, the adaptive constraint and accurate positioning involves using a clamping trolley to transfer the forging to the top of the final forging die, where the forging automatically slides into the cavity of the final forging die by its own weight.

7. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: In step S6, the thickness of the bottom small cross-section is less than 60mm.

8. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: The large-size complex variable cross-section high-temperature alloy has a diameter of Φ1130mm and a height of 354mm.

9. The method for controlling the uniformity of microstructure in large-size complex variable cross-section high-temperature alloy forging as described in claim 1, characterized in that: The heating temperature during upsetting and pre-forging is 3-5°C lower than the heating temperature during final forging.

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