A method for manufacturing a turbine disk using GH4720Li alloy

Abstract

The present invention relates to the technical field of thermal processing of nickel-based high-temperature alloy turbine disks, and in particular to a method for manufacturing turbine disks using GH4720Li alloy. The present invention first pre-treats GH4720Li alloy bars by sub-solution treatment and room temperature pre-compression treatment to obtain pre-treated bars; then the pre-treated bars are sequentially subjected to isothermal pre-forging and isothermal final forging to obtain die forgings; finally, the die forgings are subjected to post-forging heat treatment to obtain turbine disks made of GH4720Li high-temperature alloy. The present invention adopts a pre-treatment method that combines sub-solution treatment and room temperature pre-compression, which can increase the deformation ability and plasticity of the GH4720Li alloy, reduce deformation resistance during hot working, reduce cracking, obtain fine and uniform grains and a higher γ′ precipitation phase density, and provide a good foundation for subsequent hot deformation.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal processing of nickel-based high-temperature alloy turbine disks, and in particular to a method for manufacturing turbine disks by using GH4720Li alloy. Background Art

[0002] Turbine disks are core components of aircraft engines, and their performance significantly impacts the engine's thrust, efficiency, and lifespan. Because they must withstand high temperatures, high pressures, and high-speed rotational loads, turbine disks are subject to stringent requirements for toughness, corrosion resistance, and high-temperature stability. Currently, the primary material for turbine disks is nickel-based superalloys, of which GH4720Li is a γ′-phase precipitation-strengthened nickel-based superalloy with excellent high-temperature strength and thermal fatigue resistance, making it suitable for manufacturing aircraft engine turbine disks operating at temperatures between 650°C and 750°C.

[0003] The high-temperature alloy GH4720Li has a high degree of alloying and a volume fraction of the γ′ strengthening phase as high as 40% to 50%. The high alloying and high secondary phase content give the alloy high strength, toughness and high-temperature stability, but also increase the difficulty of hot forming. Due to the effects of solid solution strengthening and secondary phase strengthening, the alloy's high-temperature deformation resistance increases and its plasticity decreases, making the alloy prone to thermal cracking during hot working, leading to defects such as cracking. Therefore, the preparation of turbine disks through reasonable hot working processes is the focus and difficulty of the research on the deformation process of the GH4720Li alloy. How to effectively prepare GH4720Li alloy turbine disks with precise dimensions and uniform structure is a technical problem that urgently needs to be solved.

[0004] After searching the prior art, it was found that the Chinese patent application with publication number CN103341586A, published on October 9, 2013, discloses a method for forming GH4738 nickel-based high-temperature alloy turbine disks. This method involves wrapping a cylindrical rod blank in a hard casing and heating it. Two heating steps are performed: first, upsetting the blank and then die forging to obtain a disk forging. The disk forging is then subjected to a sub-solution heat treatment. The invention patent application with publication number CN110586822A, published on February 9, 2021, discloses a hot working method for improving the microstructure uniformity of GH720Li alloy billet forgings. The method includes the following steps: first, pre-treating the GH720Li alloy billet by heating and holding it, then sandblasting and applying glass lubricant to its surface, then heating it and rapidly sending it to a hydraulic press for the first isothermal forging; then, heating and holding the forging blank again for the second isothermal forging; and finally, subjecting the turbine disk billet forging to a slow cooling treatment. All of the above-mentioned patents propose innovative solutions for the thermal processing of high-temperature alloys. The difference between CN103341586A and CN110586822A lies in the different heat treatment methods used to process high-temperature alloy forgings. CN103341586A employs two-stage heating and forming, while CN110586822A employs isothermal forging with electric heating. However, CN103341586A does not consider the formability of the forging and die forging process, and places high demands on the press tonnage during die forging. CN110586822A uses an electric heating furnace to heat the forging temperature during isothermal forging, which has a slow heating rate, high power consumption, low efficiency, and high operating costs.

[0005] Therefore, it is crucial to provide a deformation and heat treatment process for the high-temperature alloy GH4720Li with high efficiency and easy forming. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a method for manufacturing a turbine disk using GH4720Li alloy.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a method for manufacturing a turbine disk using GH4720Li alloy, comprising the following steps:

[0009] (S1) pretreating a GH4720Li alloy rod to obtain a pretreated rod; wherein the pretreating comprises first performing a subsolution treatment on the GH4720Li alloy rod, and then performing a room temperature pre-compression treatment;

[0010] (S2) performing isothermal pre-forging and isothermal final forging on the pretreated bar obtained in step (S1) to obtain a die forging;

[0011] (S3) The die forging obtained in step (S2) is subjected to post-forging heat treatment to obtain a turbine disk made of GH4720Li high-temperature alloy.

[0012] In one embodiment of the present invention, in step (S1), the size of the GH4720Li alloy rod is Φ200mm×300mm~Φ500mm×800mm, preferably, the size of the rod is Φ400mm×600mm.

[0013] In one embodiment of the present invention, in step (S1), during the sub-solution treatment, the temperature is 1080° C. to 1110° C., the time is more than 2 hours, and the cooling method is oil cooling;

[0014] Preferably, the time is 4 hours.

[0015] In one embodiment of the present invention, in step (S1), during the room temperature pre-compression treatment, the temperature is room temperature, the reduction ratio is 5% to 10%, and the reduction rate is 30 mm / min to 100 mm / min.

[0016] In one embodiment of the present invention, in step (S2), the pretreated bar is placed in a die (turbine disc) for isothermal pre-forging and isothermal final forging;

[0017] The size of the turbine disc is Φ600mm to Φ700mm.

[0018] In one embodiment of the present invention, in step (S2), during the isothermal pre-forging process, the pretreated bar is preheated to 1070° C. to 1160° C. and kept at this temperature for 30 min to 60 min;

[0019] Furthermore, during the isothermal preforging process, the temperature difference between the pretreated bar and the die does not exceed 30°C.

[0020] In one embodiment of the present invention, during the isothermal pre-forging process, the pre-treated bar is isothermally die-forged using induction heating by a magnetic induction heating device (which significantly improves the heating efficiency and quality of the pre-treated bar, reduces oxidation and decarburization, ensures the mechanical properties and surface quality of the forging, extends the service life of the die, reduces production costs, and improves production efficiency). The pre-treated bar is compressed to a height dimensional deformation rate of 35% to 45% to obtain a forging blank.

[0021] Among them, the magnetic induction heating device includes a magnetic field power supply and a heating coil. The heating coil is wrapped around the forging die. The heating coil generates induced current and heat through the magnetic field emitted by the induction magnetic field power supply.

[0022] In one embodiment of the present invention, in step (S2), during the isothermal final forging process, the forging blank is preheated to 1070° C. to 1160° C. and kept at this temperature for 30 min to 60 min.

[0023] In one embodiment of the present invention, during the isothermal final forging process, the deformation rate of the height dimension of the forging blank during compression is 30% to 45%, and the reduction rate is 30 mm / min to 300 mm / min.

[0024] In one embodiment of the present invention, in step (S3), the post-forging heat treatment includes solution treatment and secondary aging treatment.

[0025] In one embodiment of the present invention, during the solution treatment, the temperature is 1107° C. and the time is 1 hour.

[0026] In one embodiment of the present invention, the secondary aging treatment includes a first aging treatment and a second aging treatment.

[0027] During the first aging treatment, the temperature was 760°C and the time was 8 h;

[0028] During the second aging treatment, the temperature was 650°C and the time was 16 h.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention adopts a pretreatment method that combines sub-solution treatment and room-temperature pre-compression; the sub-solution treatment can effectively adjust the distribution state of the secondary γ′ precipitation phase in the grain, and the pre-deformation treatment can improve the deformation energy storage of the GH4720Li alloy and increase the content of Σ3 twin boundaries; thereby increasing the deformation capacity and plasticity of the GH4720Li alloy, reducing deformation resistance during hot working, reducing cracking, obtaining fine and uniform grains and a higher γ′ precipitation phase density, and providing a good foundation for subsequent hot deformation.

[0031] The process of the present invention is easy to operate and suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Σ3 twin boundary distribution diagram of the microstructure of the GH4720Li alloy bar in Example 1;

[0033] Figure 2 This is the SEM image of the GH4720Li alloy rod in Example 1;

[0034] Figure 3 This is the SEM image of the rod after sub-solution treatment in Example 1;

[0035] Figure 4This is the Σ3 twin boundary distribution diagram of the pretreated rod structure obtained after pre-deformation in Example 1;

[0036] Figure 5 This is a stress comparison diagram during the strain process of the sub-solution treated rod obtained by sub-solution treatment in Comparative Example 1 and the GH4720Li alloy rod (untreated);

[0037] Figure 6 This is a stress comparison diagram during the strain process of the pretreated rod obtained by pre-deformation treatment in Comparative Example 2 and the GH4720Li alloy rod (untreated). DETAILED DESCRIPTION

[0038] The present invention provides a method for manufacturing a turbine disk using GH4720Li alloy, comprising the following steps:

[0039] (S1) pretreating a GH4720Li alloy rod to obtain a pretreated rod; wherein the pretreating comprises first performing a subsolution treatment on the GH4720Li alloy rod, and then performing a room temperature pre-compression treatment;

[0040] (S2) performing isothermal pre-forging and isothermal final forging on the pretreated bar obtained in step (S1) to obtain a die forging;

[0041] (S3) The die forging obtained in step (S2) is subjected to post-forging heat treatment to obtain a turbine disk made of GH4720Li high-temperature alloy.

[0042] Furthermore, in step (S1), the size of the GH4720Li alloy bar is Φ200mm×300mm~Φ500mm×800mm, preferably, the size of the bar is Φ400mm×600mm;

[0043] During the sub-solution treatment, the temperature is 1080° C. to 1110° C., the time is more than 2 hours, and oil cooling is adopted; preferably, the time is 4 hours.

[0044] During the normal temperature pre-compression treatment process, the temperature is normal temperature, the reduction ratio is 5% to 10%, and the reduction rate is 30 to 100 mm / min.

[0045] Furthermore, in step (S2), the pretreated bar is placed in a die (turbine disc) for isothermal pre-forging and isothermal final forging;

[0046] The size of the turbine disc is Φ600mm~Φ700mm;

[0047] During the isothermal preforging process, the pretreated bar is preheated to 1070℃~1160℃ and kept at this temperature for 30min~60min;

[0048] Furthermore, during the isothermal pre-forging process, the temperature difference between the pre-treated bar and the die does not exceed 30° C.; the pre-treated bar is compressed until the height dimensional deformation rate is 35% to 45% to obtain a forging blank.

[0049] During the isothermal final forging process, the forging blank is preheated to 1070°C to 1160°C, kept warm for 30min to 60min, and compressed until the height dimensional deformation rate of the forging blank is 30% to 45%, and the pressing rate is 30mm / min to 300mm / min.

[0050] Furthermore, in step (S3), the post-forging heat treatment includes solution treatment and secondary aging treatment.

[0051] In one embodiment of the present invention, during the solution treatment, the temperature is 1107° C. and the time is 1 hour.

[0052] In one embodiment of the present invention, the secondary aging treatment includes a first aging treatment and a second aging treatment.

[0053] During the first aging treatment, the temperature was 760°C and the time was 8 h;

[0054] During the second aging treatment, the temperature was 650°C and the time was 16 h.

[0055] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0057] Example 1

[0058] This embodiment provides a method for manufacturing a turbine disk using GH4720Li alloy (using GH4720Li alloy bars with a size of Φ400 mm × 600 mm), which specifically includes the following steps:

[0059] (S1) Subsolution treatment: GH4720Li alloy rod (its initial microstructure Σ3 twin boundary distribution diagram is as shown in the figure) Figure 1 As shown in Figure 2, the proportion of Σ3 twin boundaries in the high-angle grain boundaries is 35.3%; its SEM image is shown in Figure 2. Figure 2 As shown in the figure, the secondary γ′ precipitation phase is smaller in size and the precipitation strengthening effect is stronger) is placed in a resistance furnace, heated to 1100℃, kept warm for 4 hours, and then cooled to room temperature with oil to obtain a sub-solution treated rod (its SEM image is shown in the figure). Figure 3 As shown, the secondary γ′ precipitates are larger in size, which is conducive to deformation);

[0060] (S2) Pre-compression at room temperature: The sub-solution treated rod prepared in step (S1) is placed in a hydraulic press and compressed at room temperature at a compression rate of 50 mm / min and a reduction rate of 5% to obtain a pre-treated rod (the distribution diagram of the Σ3 twin boundaries of the rod is shown in FIG. Figure 4 As shown in the figure, the proportion of Σ3 twin boundaries in high-angle grain boundaries is 39.9%, which is 13% higher than that in the initial structure.

[0061] (S3) Isothermal pre-forging: The pre-treated bar prepared in step (S2) is blanked according to the specifications and weight required for the turbine disk, and the blank is placed in an induction coil of a mold preheated to 1150° C. for induction heating and kept warm for 30 minutes. Thereafter, isothermal pre-forging is performed at a reduction rate of 100 mm / min and a height dimensional deformation rate of 40% to obtain a forging blank;

[0062] (S4) Isothermal final forging: placing the forging blank prepared in step (S3) into a final forging die, heating it to 1150° C. and holding it there for 30 minutes, and performing isothermal final forging at a reduction rate of 100 mm / min and a height dimensional deformation rate of 40% to obtain a die forging;

[0063] (S5) Post-forging heat treatment: The die forging obtained in step (S4) is placed in a resistance furnace and subjected to the following heat treatments: solution treatment at 1107°C for 1 hour per 0.8°C (oil cooling, the same below), a first aging treatment at 760°C for 8 hours per 0.8°C (air cooling, the same below), and a second aging treatment at 650°C for 16 hours per 0.8°C to obtain a final turbine disk having a size of Φ650 mm.

[0064] Example 2

[0065] This embodiment provides a method for manufacturing a turbine disk using GH4720Li alloy (using GH4720Li alloy bars with a size of Φ300 mm × 500 mm), specifically as follows:

[0066] (S1) Subsolution treatment: The GH4720Li alloy rod was placed in a resistance furnace, heated to 1080°C, kept at this temperature for 2 h, and then cooled to room temperature with oil to obtain a subsolution treated rod.

[0067] (S2) pre-compression at room temperature: placing the solution-treated rod obtained in step (S1) into a hydraulic press, and compressing it at room temperature at a compression rate of 30 mm / min and a reduction ratio of 10% to obtain a pre-treated rod;

[0068] (S3) Isothermal pre-forging: The pre-treated bar prepared in step (S2) is blanked according to the specifications and weight required for the turbine disk, and the blank is placed in an induction coil of a mold preheated to 1070° C. for induction heating and kept warm for 50 minutes. Thereafter, isothermal pre-forging is performed at a reduction rate of 200 mm / min and a height dimensional deformation rate of 35% to obtain a forging blank;

[0069] (S4) Isothermal final forging: placing the forging blank prepared in step (S3) into a final forging die, heating the blank to 1070° C. and holding the temperature for 50 min, and performing isothermal final forging at a reduction rate of 200 mm / min and a height dimensional deformation rate of 35% to obtain a die forging;

[0070] (S5) Post-forging heat treatment: The die forging obtained in step (S4) is placed in a resistance furnace and subjected to the following heat treatments: solution treatment at 1107°C for 1 hour at 0.8°C, first aging treatment at 760°C for 8 hours at 650°C for 16 hours at 650°C for 16 hours at 650°C to obtain a final turbine disk having a size of Φ600 mm.

[0071] Example 3

[0072] This embodiment provides a method for manufacturing a turbine disk using GH4720Li alloy (using GH4720Li alloy bars with a size of Φ500 mm × 800 mm), specifically as follows:

[0073] (S1) Subsolution treatment: The GH4720Li alloy rod was placed in a resistance furnace, heated to 1110°C, kept at this temperature for 2 h, and then cooled to room temperature with oil to obtain a subsolution treated rod.

[0074] (S2) pre-compression at room temperature: placing the solution-treated rod obtained in step (S1) into a hydraulic press, and compressing it at room temperature at a compression rate of 100 mm / min and a reduction ratio of 7% to obtain a pre-treated rod;

[0075] (S3) Isothermal pre-forging: The pre-treated bar prepared in step (S2) is blanked according to the specifications and weight required for the turbine disk, and the blank is placed in an induction coil of a mold preheated to 1160° C. for induction heating and kept warm for 1 hour. Thereafter, isothermal pre-forging is performed at a reduction rate of 300 mm / min and a height dimensional deformation rate of 45% to obtain a forging blank;

[0076] (S4) Isothermal final forging: placing the forging blank prepared in step (S3) into a final forging die, heating the blank to 1160° C. and holding the temperature for 1 hour, and performing isothermal final forging at a reduction rate of 300 mm / min and a height dimensional deformation rate of 45% to obtain a die forging;

[0077] (S5) Post-forging heat treatment: The die forging obtained in step (S4) is placed in a resistance furnace and subjected to the following heat treatments: solution treatment at 1107°C for 1 hour at 0.8°C, first aging treatment at 760°C for 8 hours at 600°C, and second aging treatment at 650°C for 16 hours at 600°C, to obtain a final turbine disk having a size of Φ700 mm.

[0078] Comparative Example 1

[0079] This comparative example provides a method for manufacturing a turbine disk using GH4720Li alloy (using GH4720Li alloy bars with a size of Φ400mm×600mm), which specifically includes the following steps:

[0080] (S1) Subsolution treatment: GH4720Li alloy rod (whose hot compression mechanical properties are as follows Figure 5 As shown) was placed in a resistance furnace, heated to 1100°C, kept warm for 4 hours, and then cooled to room temperature with oil to obtain a sub-solution treated bar (its hot compression mechanical properties are shown in FIG. Figure 5 shown); through Figure 5 It can be found that the average stress of the sub-solution treated bar is reduced by 11% compared with the GH4720Li alloy bar (untreated);

[0081] (S2) Isothermal pre-forging: The bar material obtained in step (S1) after the sub-solution treatment is blanked according to the specifications and weight required for the turbine disk, and the blank is placed in an induction coil of a mold preheated to 1150° C. for induction heating and kept warm for 30 minutes. Thereafter, isothermal pre-forging is performed at a reduction rate of 100 mm / min and a height dimensional deformation rate of 40% to obtain a forging blank;

[0082] (S3) Isothermal final forging: placing the forging blank prepared in step (S2) into a final forging die, heating it to 1150° C. and holding it there for 30 minutes, and performing isothermal final forging at a reduction rate of 100 mm / min and a height dimensional deformation rate of 40% to obtain a die forging;

[0083] (S4) Post-forging heat treatment: The die forging obtained in step (S3) is placed in a resistance furnace and subjected to the following heat treatments: solution treatment at 1107°C for 1 hour at 0°C, first aging treatment at 760°C for 8 hours at AC, and second aging treatment at 650°C for 16 hours at AC, to obtain a final turbine disk having a size of Φ650 mm.

[0084] Comparative Example 2

[0085] This comparative example provides a method for manufacturing a turbine disk using GH4720Li alloy (using GH4720Li alloy bars with a size of Φ400mm×600mm), which specifically includes the following steps:

[0086] (S1) Pre-compression at room temperature: GH4720Li alloy rod (whose hot compression mechanical properties are as follows Figure 6 As shown) was put into a hydraulic press and compressed at room temperature at a compression rate of 50 mm / min and a reduction rate of 5% to obtain a pretreated rod (its hot compression mechanical properties are shown in FIG. Figure 6 shown); through Figure 6 It can be found that the average stress of the pretreated rod is reduced by 13% compared with the GH4720Li alloy rod (untreated);

[0087] (S2) Isothermal pre-forging: The pre-treated bar prepared in step (S1) is blanked according to the specifications and weight required for the turbine disk, and the blank is placed in an induction coil of a mold preheated to 1150° C. for induction heating and kept warm for 30 minutes. Thereafter, isothermal pre-forging is performed at a reduction rate of 100 mm / min and a height dimensional deformation rate of 40% to obtain a forging blank;

[0088] (S3) Isothermal final forging: placing the forging blank prepared in step (S2) into a final forging die, heating it to 1150° C. and holding it there for 30 minutes, and performing isothermal final forging at a reduction rate of 100 mm / min and a height dimensional deformation rate of 40% to obtain a die forging;

[0089] (S4) Post-forging heat treatment: The die forging obtained in step (S3) is placed in a resistance furnace and subjected to the following heat treatments: solution treatment at 1107°C for 1 hour at 0°C, first aging treatment at 760°C for 8 hours at AC, and second aging treatment at 650°C for 16 hours at AC, to obtain a final turbine disk having a size of Φ650 mm.

[0090] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the explanations of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for manufacturing a turbine disk using GH4720Li alloy, characterized in that: The following steps are involved: (S1) pretreating a GH4720Li alloy rod to obtain a pretreated rod; wherein the pretreating comprises first performing a subsolution treatment on the GH4720Li alloy rod, and then performing a room temperature pre-compression treatment; (S2) performing isothermal pre-forging and isothermal final forging on the pretreated bar obtained in step (S1) to obtain a die forging; (S3) The die forging obtained in step (S2) is subjected to post-forging heat treatment to obtain a turbine disk made of GH4720Li high-temperature alloy.

2. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 1, characterized in that: In step (S1), during the sub-solution treatment, the temperature is 1080°C to 1110°C and the time is more than 2 hours.

3. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 1, characterized in that: In step (S1), during the normal temperature pre-compression process, the temperature is normal temperature and the reduction rate is 5% to 10%.

4. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 1, characterized in that: In step (S2), during the isothermal pre-forging process, the pretreated bar is preheated to 1070° C. to 1160° C. and kept warm for 30 min to 60 min.

5. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 4, characterized in that: During the isothermal pre-forging treatment process, the pre-treated bar is compressed to a height dimensional deformation rate of 30% to 45% to obtain a forging blank.

6. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 5, characterized in that: In step (S2), during the isothermal final forging process, the forging blank is preheated to 1070°C to 1160°C and kept warm for 30min to 60min.

7. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 6, characterized in that: During the isothermal final forging process, the deformation rate of the height dimension of the forging blank is compressed to 30% to 45%.

8. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 1, characterized in that: In step (S3), the post-forging heat treatment is to first perform a solid solution treatment on the die forging and then perform a secondary aging treatment.

9. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 8, characterized in that: During the solution treatment process, the temperature was 1107°C and the time was 1 h.

10. The method for manufacturing a turbine disk using GH4720Li alloy according to claim 8, characterized in that: Secondary aging treatment includes the first aging treatment and the second aging treatment. During the first aging treatment, the temperature was 760°C and the time was 8 h; During the second aging treatment, the temperature was 650°C and the time was 16 h.

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