Preparation method of GH4169 alloy disc part

Abstract

The invention provides a preparation method of a GH4169 alloy disc part, and belongs to the technical field of preparation of deformed high-temperature alloy parts for aerospace. The preparation method comprises the steps that a GH4169 alloy cast ingot is prepared through triple smelting; carrying out two-step diffusion annealing treatment to obtain an annealed cast ingot; the annealed cast ingot is subjected to multi-direction forging blank manufacturing, and a round bar blank is forged; pressing the round bar blank into a cake blank; carrying out isothermal die forging on the cake blank to prepare a disc blank; the disc blank is subjected to solid solution aging treatment; and the disc blank is machined, and the disc part is obtained. By optimizing the smelting, forging and heat treatment processes, the structure uniformity and mechanical property of the GH4169 alloy disc part are remarkably improved, high-purity, high-uniformity and high-performance disc part preparation is achieved, the service life of parts can be prolonged, the equipment safety is improved, meanwhile, the alloy yield is effectively increased, a guarantee is provided for preparation of the high-temperature-resistant disc part, and the production cost is reduced. And the use requirement of an advanced aero-engine on the high-temperature alloy disc is met.

Description

Technical Field

[0001] This application belongs to the field of preparation technology of deformed high-temperature alloy parts for aerospace, and specifically relates to a method for preparing GH4169 alloy disc-shaped parts. Background Technology

[0002] GH4169 (also known as Inconel 718) is a nickel-based superalloy. Due to its excellent high-temperature strength, fatigue resistance, oxidation resistance and good processing performance, it is widely used in key hot-end components such as aero engines and gas turbines, especially disc components such as turbine disks and compressor disks. Aero engine turbine disks withstand high temperatures, high pressures and high-speed rotational loads of 650-700℃ and are the core components for engine power transmission. Gas turbine rotor disks have been in service for a long time in high-temperature gas environments and need to resist creep and thermal fatigue. Spacecraft propulsion systems (such as rocket engine turbopump disks) also require extremely high reliability.

[0003] Failure of disc-shaped components can lead to catastrophic engine accidents (such as non-containment fracture), therefore their performance directly determines the safety and lifespan of aircraft. Improving the thrust-to-weight ratio of high-performance engines relies on the temperature resistance and microstructural stability of materials; GH4169 is currently the most widely used 650℃-grade disc material. Because disc-shaped components are subjected to complex multiaxial stresses and gradient temperature fields during service, any local microstructural inhomogeneity can become a crack initiation point. Therefore, extremely high requirements are placed on their performance uniformity, requiring an overall grain size ≥ 8 (ASTM standard). However, traditional processes easily lead to grain differences between the core and edges of the disc (such as coarse grains at the blade tip and mixed grains in the core), inducing fatigue cracks. The main strengthening phases γ′′ (Ni3Nb) and γ′ (Ni3(Al,Ti)) need to be uniformly dispersed; local aggregation will reduce the alloy's fatigue life.

[0004] Existing GH4169 alloy disc-shaped parts manufacturing technologies typically employ duplex melting (VIM+VAR) or inverted triple melting (VIM+VAR+ESR) to prepare ingots. While duplex melting can reduce gas content, it is still difficult to completely eliminate Nb segregation (black spots) and oxide inclusions (white spots), resulting in insufficient material purity and affecting fatigue performance. Although inverted triple melting can improve segregation, the ESR process introduces new inclusions. When preparing disc blanks using unidirectional drawing and ordinary forging processes from ingots, the unidirectional drawing method easily leads to grain elongation along the deformation direction, forming a banded structure. This results in significant differences in grain size between the center and the edge of the disc, affecting overall mechanical properties. Uneven deformation temperature in ordinary die forging easily causes abnormal local grain growth or insufficient recrystallization of mixed-grain structures with poor grain size (≥4 grade), which reduces the high-cycle fatigue life of disc-shaped parts and causes large performance fluctuations (strength standard deviation ±50MPa, high fatigue life dispersion).

[0005] Therefore, a new approach is needed to prepare GH4169 alloy disk-like components in order to improve their performance. Summary of the Invention

[0006] To address the aforementioned issues, this application proposes a process route of "triple melting (VIM+ESR+VAR) + two-step diffusion annealing + multi-directional forging + isothermal forging," which significantly improves the microstructure uniformity and mechanical properties of GH4169 alloy disc-shaped parts.

[0007] This application is achieved through the following technical solution: A method for preparing a GH4169 alloy disc-shaped part includes the following steps: S1. Tri-melting: GH4169 alloy ingots are prepared by vacuum induction melting, electroslag remelting and vacuum arc remelting. S2. Perform a two-step diffusion annealing treatment on the GH4169 alloy ingot to obtain an annealed ingot. S3. Multi-directional forging billet preparation: The annealed ingot is forged into a square billet, and then forged 4-8 times along the x, y, and z axes. The last forging is a single-phase elongation forging into a round bar billet. The forging temperature is 1050-1080℃, the final forging temperature is higher than 930℃, and the deformation per forging is ≥40%. S4. Press the round bar billet into a disc; S5. The blank is subjected to isothermal die forging to prepare a disc blank: the forging temperature of isothermal die forging is 960-990℃, the deformation is 50-80%, and the strain rate is ≤0.01s. -1 ; S6. Perform solution aging treatment on the billet; S7. Machining the blank into disc-shaped parts.

[0008] Furthermore, the GH4169 alloy ingot, by mass percentage, has the following chemical composition: C 0.02-0.06%, Cr 17-21%, Ni 50-55%, Co≤1%, Mo 2.8-3.3%, Al 0.2-0.8%, Ti 0.65-1.15%, Nb 5.0-5.5%, B≤0.006%, Mg≤0.005%, P≤0.0015%, with the balance being Fe and unavoidable impurities.

[0009] Furthermore, the diameter of the GH4169 alloy ingot is 300-508 mm.

[0010] Furthermore, the triple smelting process includes sequential vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR) to prepare high-purity GH4169 alloy ingots, ensuring the absence of black spots (Nb segregation) and white spots (oxide inclusions). VIM is used to pre-alloy the ingot raw materials, precisely controlling the chemical composition of the GH4169 alloy ingot. The VIM refining temperature is preferably 150-300°C above the alloy liquidus line, and the refining time is controlled at 30-90 minutes to promote inclusion flotation and gas removal. Then, a high-basicity, CaO-Al2O3-based refining slag is used to adsorb and desulfurize, removing some oxide inclusions. Simultaneously, a ceramic filter (yttrium oxide or Al2O3 foam ceramic) is used to intercept large-sized inclusions.

[0011] The purity of the metal is improved by deep removal of non-metallic inclusions such as sulfur and oxygen from the molten metal using ESR (Expanded Sedimentation Removal). A high-basicity, low-oxidizing slag system is selected during the ESR process, and a low melting rate (1.5-3 kg / min) is used to prolong the slag-metal reaction time, which is beneficial for inclusion absorption and composition homogenization. Vapor-reflective annealing (VAR) is then used to further eliminate porosity and microsegregation. A "slow initiation + stable melting" strategy is adopted during the VAR process: low current is used during the initiation stage to avoid splashing, a constant melting rate (3-6 mm / min) is maintained during the main melting period, and the melting rate is reduced at the end for feeding. The GH4169 alloy ingots produced by this three-stage smelting process have an oxygen content ≤10 ppm and a sulfur content ≤5 ppm.

[0012] Furthermore, the GH4169 alloy ingot undergoes a two-step diffusion annealing process, comprising: a first-step diffusion annealing process at 1120-1170℃ for 10-20 hours, and a second-step diffusion annealing process at 1180-1200℃ for 24-50 hours, to obtain an annealed ingot; the two-step segmented annealing homogenization process promotes the diffusion of metallic elements such as Nb and Ti, eliminates dendrites and element segregation in the ingot, makes the ingot structure uniform, and avoids grain boundary embrittlement.

[0013] Furthermore, in the multi-directional forging billet, the equiaxed crystal ratio of the round bar billet is ≥90%, and the grain size is greater than ASTM grade 6. Multi-directional forging billet can break up coarse as-cast structures, improve equiaxed crystals, and refine grain size. Preferably, the equiaxed crystal ratio can be ≥92%, and the grain size can be refined to ASTM grade 8 or higher.

[0014] Furthermore, the diameter of the round bar blank is 150-250mm.

[0015] Furthermore, the temperature at which the round bar billet is pressed into a disc is 960-990℃, and the deformation is ≥50%.

[0016] Furthermore, the grain size of the blank is ASTM 9-12 grade, with a grade difference of ≤2 grades.

[0017] Preferably, the isothermal forging die is preheated to the same temperature as the blank to avoid insufficient filling of the prepared blank due to temperature drop.

[0018] Furthermore, the solution aging treatment of the billet includes: a solution stage, heating to 960-1000℃ and holding at that temperature for 1-4 hours followed by air cooling; a first aging stage, heating to 700-750℃ and holding at that temperature for 5-10 hours followed by furnace cooling; and a second aging stage, heating to 600-650℃ and holding at that temperature for 5-10 hours followed by air cooling. Through solution and double aging treatments, the uniform distribution of the strengthening phase is optimized, thereby improving the tensile strength and yield strength of the alloy.

[0019] Furthermore, the blank is machined to obtain a disc-shaped part, including: precision machining using CNC machine tools, with a disc dimensional tolerance ≤ ±0.05mm and a surface roughness Ra ≤ 1.6μm.

[0020] Compared with the prior art, this application has the following advantages: The GH4169 alloy disc-shaped parts prepared in this application have a room temperature tensile strength greater than 1400 MPa, a yield strength greater than 1100 MPa, and an elongation after fracture greater than 15%. At 650℃, the high-temperature strength is: tensile strength greater than 1200 MPa, yield strength greater than 1040 MPa, and elongation after fracture greater than 15%. The stress at 500℃ / 1100 MPa (stress ratio R=0.05, frequency 0.33 Hz, maximum stress σ) is also specified. max The fatigue life under conditions of 1100 MPa is greater than 105 cycles. This application significantly improves the microstructure uniformity and mechanical properties of GH4169 alloy disc-shaped parts by optimizing the smelting, forging, and heat treatment processes. It achieves the preparation of disc-shaped parts with high purity (no black / white spots), high uniformity (uniform grain / strengthening phase distribution), and high performance (high room temperature tensile strength, high fatigue life), and improves the yield. It is suitable for the preparation of integral bladed disks and turbine disks for compressors that can withstand 650-700℃. After being applied to a turbine disk of a certain type of aero-engine, the ultrasonic noise level was reduced by 40%, the standard deviation of room temperature tensile strength was reduced from ±50 MPa to ±20 MPa, and the standard deviation of overall performance was reduced by 60%, which significantly improved the reliability and life of key components of aero-engines.

[0021] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 Microstructure of the GH4169 turbine disk prepared for Example 1; Figure 2 Microstructure of the GH4169 alloy bladed disk prepared for Example 2; Figure 3 Microstructure of the GH4169 turbine disk prepared for Example 3; Figure 4 The microstructure of the GH4169 alloy disc-shaped part prepared for Comparative Example 1. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Example 1 A method for preparing a GH4169 alloy turbine disk includes the following steps: S1. Triple Melting: GH4169 alloy ingots were prepared by vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR), including: Vacuum induction melting (VIM): According to the design composition of GH4169 alloy ingot, the following raw materials are added: C 0.03%, Cr 17.5%, Ni 52%, Co 0.05%, Mo 3.0%, Al 0.4%, Ti 1.0%, Nb 5.2%, B 0.005%, Mg 0.002%, P 0.0005%, impurity content <0.01%, and the remainder is Fe.

[0026] Vacuum induction VIM: Refining at 1500℃ for 40 minutes; Electroslag Remelting (ESR): Melting rate is 2 kg / min; Vacuum self-consumable melting (VAR): melting speed is 4 mm / min; A GH4169 alloy ingot with a diameter of 508mm and no black or white spots was obtained, with the sulfur content reduced to 4ppm and the oxygen content ≤8ppm.

[0027] S2. The GH4169 alloy ingot is subjected to a two-step diffusion annealing treatment to obtain an annealed ingot, including: the first step of diffusion annealing is annealing at 1160℃ for 20h to dissolve dendrite segregation and Laves phase; the second step of diffusion annealing is annealing at 1190℃ for 24h to allow Nb and Ti elements to diffuse uniformly, thus obtaining an annealed ingot.

[0028] S3. Multi-directional forging billet preparation: The annealed ingot is forged into a square billet, and then forged in four passes along the x, y, and z axes. The first forging temperature is 1080℃, the second forging temperature is 1060℃, the third forging temperature is 1050℃, and the final forging temperature is 1050℃, followed by single-phase elongation forging into a Φ200mm round bar billet. The final forging temperature is 940℃, and the deformation per pass is 45%. The equiaxed grain ratio of the round bar billet is ≥92%, and the grain size meets ASTM grade 8.

[0029] S4. Pressing the round bar billet into a disc, including: preparing a Φ600mm×150mm disc from the round bar billet at 980℃ with a deformation of 60%.

[0030] S5. Isothermal forging of the billet to prepare a disc: Preheat the isothermal forging die to 970℃, and perform low-speed deformation forging at 970℃ (strain rate 0.008s). -1 The deformation amount is 70%, and a blank is obtained; the grain size is ASTM 10-11 grade, and the grade difference is ≤1 grade.

[0031] S6. Perform solution aging treatment on the billet, including: solution stage, heating the billet to 980℃ and holding it at a constant temperature for 2 hours, then air cooling; first aging stage, heating to 720℃ and holding it at a constant temperature for 8 hours, then furnace cooling; second aging stage, heating to 620℃ and holding it at a constant temperature for 8 hours, then air cooling.

[0032] S7. The blank is machined to obtain the turbine disk. The disk dimensional tolerance is ±0.04mm, and the surface roughness is Ra1.4μm. Ultrasonic testing meets AAA grade, and the yield is 90%.

[0033] In this embodiment, the turbine disk is organized as follows: Figure 1 The tensile strength at room temperature is 1420±6 MPa, the yield strength is 1130±5 MPa, and the elongation is 18±2%. At 650℃, the tensile strength is 1230±12 MPa, the yield strength is 1060±5 MPa, and the elongation is 19±4%. The fatigue life at 500℃ / 1100 MPa stress is 1.2×10⁻⁶ MPa. 5 Week.

[0034] Example 2 A method for manufacturing a GH4169 alloy compressor bladed disk includes the following steps: S1. Triple Melting: GH4169 alloy ingots were prepared by vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR), including: Vacuum induction melting (VIM): According to the design composition of GH4169 alloy ingot, the following raw materials are added: C 0.04%, Cr 18.5%, Ni 53%, Co 0.1%, Mo 3.1%, Al 0.3%, Ti 0.9%, Nb 5.2%, B 0.003%, Mg 0.002%, P 0.0005%, impurity content ≤0.005%, and the remainder is Fe.

[0035] Vacuum induction VIM: Refining at 1550℃ for 35 minutes; Electroslag Remelting (ESR): Melting rate is 3 kg / min; Vacuum self-consumable melting (VAR): melting speed is 5 mm / min; A GH4169 alloy ingot with a diameter of 508mm and no black or white spots was obtained, with the sulfur content reduced to 4ppm and the oxygen content ≤8ppm.

[0036] S2. The GH4169 alloy ingot is subjected to a two-step diffusion annealing treatment to obtain an annealed ingot, including: the first step of diffusion annealing is annealing at 1160℃ for 20h to dissolve dendrite segregation and Laves phase; the second step of diffusion annealing is annealing at 1190℃ for 24h to allow Nb and Ti elements to diffuse uniformly, thus obtaining an annealed ingot.

[0037] S3. Multi-directional forging billet preparation: The annealed ingot is forged into a square billet, and then forged in five passes along the x, y, and z axes. The forging temperature for the first pass is 1080℃, the second pass is 1070℃, the third pass is 1060℃, the fourth pass is 1050℃, and the final pass is 1050℃, followed by single-phase elongation forging into a Φ250mm round bar billet. The final forging temperature is 940℃, and the deformation per pass is 45%. The equiaxed grain ratio of the round bar billet is ≥92%, and the grain size meets ASTM grade 8.

[0038] S4. Pressing the round bar billet into a disc, including: preparing a Φ600mm×150mm disc from the round bar billet at 980℃ with a deformation of 60%.

[0039] S5. The blank is isothermally forged to prepare the disc blank: the isothermal forging die is preheated to 965℃, the bladed disk hub is pre-forged at 965℃ (deformation amount 50%), and the blade part is finally forged (deformation amount 80%). The grain size of the blade area is ASTM grade 11, and the grain size of the hub area is ASTM grade 10, with a grade difference ≤ 1.

[0040] S6. Perform solution aging treatment on the billet, including: solution stage, heating the billet to 995℃ and holding it at a constant temperature for 3 hours, then air cooling; first aging stage, heating to 730℃ and holding it at a constant temperature for 10 hours, then furnace cooling; second aging stage, heating to 630℃ and holding it at a constant temperature for 10 hours, then air cooling.

[0041] S7. The blank is machined to obtain the bladed disk with a surface accuracy of ±0.03mm, ultrasonic testing meets AAA grade, and the yield is 85%.

[0042] In this embodiment, the structure of the impeller is as follows: Figure 2 The tensile strength at room temperature is 1450±5 MPa, the yield strength is 1140±7 MPa, and the elongation is 16±2%. At 650℃, the tensile strength is 1280±15 MPa, the yield strength is 1100±9 MPa, and the elongation is 18±3%. The fatigue life under 500℃ / 1100 MPa stress is 1.4×10⁻⁶. 5 Week.

[0043] Example 3 This application discloses a method for preparing a GH4169 alloy turbine disk, comprising the following steps: S1. Triple Melting: GH4169 alloy ingots were prepared by vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR), including: Vacuum induction melting (VIM): According to the design composition of GH4169 alloy ingot, the following raw materials are added: C 0.05%, Cr 17%, Ni 52.5%, Co 0.05%, Mo 3.0%, Al 0.4%, Ti 1.0%, Nb 5.2%, B 0.003%, Mg 0.002%, P 0.0005%, impurity content ≤0.005%, and the remainder is Fe.

[0044] Vacuum induction VIM: Refining at 1580℃ for 60 minutes; Electroslag Remelting (ESR): Melting rate is 3 kg / min; Vacuum self-consumable melting (VAR): melting speed is 6 mm / min; A GH4169 alloy ingot with a diameter of 508 mm and no black or white spots was obtained, with the sulfur content reduced to 4 ppm and the oxygen content ≤ 8 ppm.

[0045] S2. The GH4169 alloy ingot is subjected to a two-step diffusion annealing treatment to obtain an annealed ingot, including: the first step of diffusion annealing is annealing at 1160℃ for 20h to dissolve dendrite segregation and Laves phase; the second step of diffusion annealing is annealing at 1190℃ for 24h to allow Nb and Ti elements to diffuse uniformly, thus obtaining an annealed ingot.

[0046] S3. Multi-directional forging billet preparation: The annealed ingot is forged into a square billet, and then forged in six passes along the x, y, and z axes. The forging temperatures are as follows: first pass 1080℃, second pass 1070℃, third pass 1060℃, fourth pass 1060℃, fifth pass 1050℃, and final pass 1050℃, followed by single-phase elongation forging into a Φ180mm round bar billet. The final forging temperature is 940℃, and the deformation per pass is 45%. The equiaxed grain ratio of the round bar billet is ≥92%, and the grain size meets ASTM grade 8.

[0047] S4. Pressing the round bar billet into a disc, including: preparing a Φ550mm×160mm disc from the round bar billet at 975℃ with a deformation of 55%.

[0048] S5. Isothermal forging of the billet to prepare a disc: Preheat the isothermal forging die to 965℃, and perform low-speed deformation forging at 965℃ (strain rate 0.007s). -1 The deformation amount is 75%, and a blank is obtained; the grain size is ASTM 10-12 grade, with a grade difference ≤ 1 grade.

[0049] S6. Perform solution aging treatment on the billet, including: solution stage, heating the billet to 990℃ and holding it at a constant temperature for 2.5h and then air cooling; first aging stage, heating to 710℃ and holding it at a constant temperature for 9h and then furnace cooling; second aging stage, heating to 610℃ and holding it at a constant temperature for 9h and then air cooling.

[0050] S7. The blank is machined to obtain the turbine disk. The disk dimensional tolerance is ±0.03 mm, and the surface roughness is Ra1.2 μm. Ultrasonic testing meets AAA grade, and the yield is 80%.

[0051] In this embodiment, the turbine disk is organized as follows: Figure 3 As shown, the room temperature tensile strength is 1440±10 MPa, yield strength is 1120±8 MPa, and elongation is 17±2%; the high-temperature strength at 650℃ is: tensile strength 1250±15 MPa, yield strength 1050±9 MPa, and elongation 18±4%; the fatigue life under stress at 500℃ / 1100MPa is 1.3×10⁻⁶ MPa. 5 Week.

[0052] Comparative Example 1 The preparation method of GH4169 alloy disc-shaped parts includes the following steps: S1: Dual melting (VIM+VAR): Add raw materials according to the same design composition as in Example 1, vacuum induction melting (VIM): refine at 1450°C for 60 min; vacuum consumable melting (VAR): melting speed is 8 mm / min.

[0053] A GH4169 alloy ingot with a diameter of 508 mm was obtained. The obtained alloy ingot showed local Nb segregation, sulfur content of 12 ppm, and oxygen content of 18 ppm.

[0054] S2: Unidirectional drawing forging: The alloy ingot is unidirectionally drawn into a Φ200mm round bar billet at a forging temperature of 1050-1080℃, with a final forging temperature of 920℃ and 4 forging cycles, resulting in a cumulative deformation of 85%; its unidirectional deformation leads to a banded structure; the grain size difference reaches level 4 (ASTM level 8 for the rim and level 4 for the core).

[0055] S3: Die forging: Forging once at 950-1000℃, with large fluctuations in deformation temperature, abnormal growth of local grains, and the presence of mixed-grain structure.

[0056] S4: Solution treatment: 950℃ / 1h air cooling; Aging: 700℃ / 8h furnace cooling + 620℃ / 8h air cooling. Ultrasonic testing meets AA grade, yield is 75%.

[0057] The microstructure of the disk-like components obtained in Comparative Example 1 is as follows: Figure 4 As shown, the room temperature tensile strength is 1350±60MPa, and the yield strength is 1000±55MPa; the high-temperature strength at 650℃ is 1150±50MPa; the fatigue life under stress at 500℃ / 1100MPa is 6×10⁻⁶. 4 Weekly cycle; high dispersion in mechanical properties, and obvious noise signals were observed during ultrasonic testing.

[0058] Comparative Example 2 The preparation method of GH4169 alloy disc-shaped parts includes the following steps: S1: Triple Smelting: Add raw materials according to the same design composition as in Example 1. Vacuum induction VIM: Refining at 1450℃ for 60 minutes; Electroslag Remelting (ESR): Melting speed is 5 kg / min; Vacuum self-consumable melting (VAR): melting speed is 10 mm / min; A GH4169 alloy ingot with a diameter of 508 mm was obtained. The obtained alloy ingot had local Nb segregation, sulfur content of 10 ppm, and oxygen content of 15 ppm.

[0059] S2: Unidirectional drawing forging: The alloy ingot is unidirectionally drawn into a Φ250mm round bar billet at a forging temperature of 1050-1080℃, with a final forging temperature of 920℃ and 6 forging cycles, resulting in a cumulative deformation of 75.7%; its unidirectional deformation leads to a banded structure; the grain size difference reaches level 4 (ASTM level 8 for the rim and level 4 for the core).

[0060] S3: Die forging: Forging once at 950-1000℃ results in large temperature fluctuations during deformation, abnormal grain growth in some areas, and the presence of mixed grain structure.

[0061] S4: Solution treatment: 950℃ / 1h air cooling; Aging: 700℃ / 8h furnace cooling + 620℃ / 8h air cooling. Ultrasonic testing meets AA grade. Yield is 70%.

[0062] The disc-shaped component obtained in Comparative Example 2 has a room temperature tensile strength of 1370±50 MPa and a yield strength of 1050±40 MPa; a high-temperature strength at 650℃: tensile strength of 1180±45 MPa; and a fatigue life at 500℃ / 1100 MPa stress of 8.8×10⁻⁶. 4 Week.

[0063] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a GH4169 alloy disc-shaped part, characterized in that, Includes the following steps: S1. Tri-melting: GH4169 alloy ingots are prepared by vacuum induction melting, electroslag remelting and vacuum arc remelting. S2. Perform two-step diffusion annealing on the GH4169 alloy ingot to obtain an annealed ingot. S3. Multi-directional forging billet preparation: The annealed ingot is forged into a square billet, and then forged 4-8 times along the x, y, and z axes. The last forging is a single-phase elongation forging into a round bar billet. The forging temperature is 1050-1080℃, the final forging temperature is higher than 930℃, and the deformation per forging is ≥40%. S4. Press the round bar billet into a disc; S5. The blank is subjected to isothermal die forging to prepare a disc blank: the forging temperature of isothermal die forging is 960-990℃, the deformation is 50-80%, and the strain rate is ≤0.01s. -1 ; S6. Perform solution treatment and aging on the billet; S7. Machining the blank into disc-shaped parts.

2. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The GH4169 alloy ingot, by mass percentage, has the following chemical composition: C 0.02-0.06%, Cr 17-21%, Ni 50-55%, Co≤1%, Mo 2.8-3.3%, Al 0.2-0.8%, Ti 0.65-1.15%, Nb 5.0-5.5%, B≤0.006%, Mg≤0.005%, P≤0.0015%, with the balance being Fe and unavoidable impurities.

3. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The diameter of the GH4169 alloy ingot is 300-508 mm.

4. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The two-step diffusion annealing process for the GH4169 alloy ingot includes: a first diffusion annealing process of annealing at 1120-1170℃ for 10-20 hours, and a second diffusion annealing process of annealing at 1180-1200℃ for 22-26 hours, to obtain the annealed ingot.

5. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The equiaxed grain ratio of the round bar billet in the multi-directional forging process is ≥90%, and the grain size is greater than ASTM grade 6.

6. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The diameter of the round bar billet is 150-250mm.

7. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The temperature at which the round bar billet is pressed into a disc is 960-990℃, and the deformation is ≥50%.

8. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The grain size of the blank is ASTM 9-12 grade, with a grade difference of ≤2 grades.

9. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The solution aging treatment of the billet includes: a solution stage, heating to 960-1000℃ and holding at a constant temperature for 1-4 hours followed by air cooling; a first aging stage, heating to 700-750℃ and holding at a constant temperature for 5-10 hours followed by furnace cooling; and a second aging stage, heating to 600-650℃ and holding at a constant temperature for 5-10 hours followed by air cooling.

10. The method for preparing a GH4169 alloy disc-shaped part according to claim 1, characterized in that, The blank is machined to obtain a disc-shaped part, including: precision machining using CNC machine tools, with a disc size tolerance ≤ ±0.05mm and a surface roughness Ra ≤ 1.6μm.

Images