A method for preparing a Ti2AlNb / TC4 dual-alloy disc

Abstract

The application provides a preparation method of a Ti2AlNb / TC4 dual-alloy disc, which comprises dual-alloy welding combination structure design, welding tool and forging die design and processing, dual-alloy fine-grain blank preparation and processing, dual-alloy diffusion welding, forging shaping, heat treatment and processing; the specific operation process is described as follows. Firstly, the dual-alloy ring-shaped matching surface with a taper is designed and processed to convert the axial loading force into the radial welding force, and then the fine-grain blank is prepared to promote the heterogeneous alloy components to diffuse and fuse through the grain boundary in the welding process, and then the dual-alloy welding combination blank is forged and shaped, so that the interface form position of the dual-alloy is controlled, the grain boundary slip and dislocation "channel" in the forging process are utilized to promote the fusion of the heterogeneous alloy components in the interface bonding area, and then the interface performance level is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal hot working, in particular to a preparation method of a Ti2AlNb / TC4 dual-alloy disc. BACKGROUND

[0002] Lightweight and high performance is the eternal pursuit of aviation manufacturing. As a rotor component in the engine, the compressor disc puts forward performance requirements for the disc body in terms of service conditions: the disc rim is connected with the blade, bears high temperature and small force, and focuses on the creep resistance and fracture toughness of the material; the disc core is connected with the shaft, bears low temperature but large force (centrifugal force), and focuses on the strength, plasticity and fatigue performance of the material. The performance requirements challenge the disc manufacturing technology.

[0003] At present, deformed high-temperature alloy is mainly used to process high-pressure compressor discs in China, and the material selection is conservative. There are problems such as large structure weight and single performance, which is difficult to meet the lightweight and high-efficiency development requirements of the engine. Therefore, it is urgent to develop a dual-alloy dual-performance disc using high-performance lightweight materials and high-performance cutting structures.

[0004] Ti2AlNb alloy is a new type of lightweight intermetallic compound material, and its maximum use temperature is higher than 700 DEG C. However, the plasticity of the alloy is low, which cannot meet the performance requirements of the disc core. If Ti2AlNb is selected as the rim material and combined with TC4 alloy (the disc core material) with a temperature of about 400 DEG C to prepare a Ti2AlNb / TC4 dual-alloy disc, the performance advantages of the two alloys can be utilized to meet the design requirements of the performance.

[0005] For the dual-alloy disc, defect-free metallurgical bonding at the connecting interface is the key to the development of the disc. Previous researchers have conducted a lot of research on the manufacturing and microstructure performance control of the Ti2AlNb / Ti dual-alloy disc. The dual-alloy disc interface bonding area prepared by high-energy beam welding (+ forging), inertia friction welding (+ forging) and additive manufacturing has problems such as welding defects and overheated microstructure in the heat affected zone, which limits the engineering application of the dual-alloy disc. Therefore, it is urgent to find a new method for the development of Ti2AlNb / Ti dual-alloy disc. SUMMARY

[0006] Therefore, the present application provides a preparation method of a Ti2AlNb / TC4 dual-alloy disc. The method provided by the present application can solve the bottleneck problem of weak connection at the dual-alloy interface, and the interface connection of the Ti2AlNb / TC4 dual-alloy disc prepared by the method is reliable, which can meet the performance requirements and weight reduction requirements of the compressor disc.

[0007] The present application provides a preparation method of a Ti2AlNb / TC4 dual-alloy disc, which comprises the following steps:

[0008] (1) Dual-alloy welding combined structure design:

[0009] Based on the structural dimensions of the Ti2AlNb / TC4 bialloy disk, the matching design of the bialloy welded composite billet structure and the forging structure is carried out by combining numerical simulation.

[0010] The dual-alloy welded composite billet is a combination structure of a Ti2AlNb alloy outer ring billet and a TC4 alloy inner ring billet, or a combination structure of a Ti2AlNb alloy outer ring billet and a TC4 alloy inner frustum billet.

[0011] (2) Design and fabrication of welding fixtures and forging dies:

[0012] Based on the design and processing of the high-temperature alloy collar welding fixture according to the structure of the double alloy welded composite billet determined in step (1), and based on the design and processing of the forging die according to the structure of the forging determined in step (1);

[0013] (3) Preparation and processing of fine-grained bialloy billets:

[0014] A fine-grained billet of TC4 alloy is obtained by repeated upsetting and forging. Then, it is machined according to the dimensions of the inner ring billet / inner frustum billet of TC4 alloy to obtain the TC4 alloy billet. A fine-grained ring billet of Ti2AlNb alloy is obtained by repeated upsetting and forging and punching. After deformation, it is machined according to the dimensions of the outer ring billet of Ti2AlNb alloy to obtain the outer ring billet of Ti2AlNb alloy.

[0015] (4) Bialloy diffusion welding:

[0016] The TC4 alloy billet and the Ti2AlNb alloy outer ring billet are assembled, and then a preheated collar-type welding fixture is installed on the outside of the Ti2AlNb alloy outer ring billet. Then, it is placed in a vacuum diffusion welding furnace for diffusion welding. After that, the outer collar-type welding fixture is removed to obtain a bi-alloy welded composite billet.

[0017] (5) Forging and shaping:

[0018] The bialloy welded composite billet obtained in step (4) is preheated and then placed into the forging mold designed in step (2) for forging and shaping. After forging, it is air-cooled to obtain a bialloy disc forging.

[0019] (6) Heat treatment:

[0020] The bialloy disc forging is annealed.

[0021] (7) Processing:

[0022] The bialloy forged disc obtained in step (6) is machined by turning to obtain the bialloy disc part.

[0023] Preferably, in step (1), the double-alloy welding interface in the double-alloy welding combined blank forms an angle of 10°-30° with the axis.

[0024] The matching design of the double-alloy welding combined blank structure and the forged structure makes the double-alloy interface parallel to the axis of the forged product at the end of the subsequent step (5) of forging.

[0025] Preferably, in step (2), the sleeve-type welding tool is designed to have an interference fit with the Ti2AlNb alloy outer ring blank.

[0026] Preferably, in step (3), the upsetting temperature of the TC4 alloy is T β -(50-80)℃, wherein T β is the phase transition point of the TC4 alloy; the machining tolerance of the outer conical surface after machining is +0.5mm to +1.0mm, and the surface roughness Ra is ≤1.6μm.

[0027] The deformation temperature of the Ti2AlNb alloy is located in the lower part of the (α2+B2+O) phase region, the machining tolerance of the inner conical surface after machining is -1.0mm to -0.5mm, and the surface roughness Ra is ≤1.6μm.

[0028] Preferably, in step (4), the diffusion welding conditions are as follows: the welding temperature T β is (50-80)℃, the pressure is 10-20MPa, and the pressure holding time is 1-4h.

[0029] Preferably, in step (5), the preheating temperature is T β -(15-50)℃; and the preheating time is calculated according to the maximum cross-sectional thickness δ max of the double-alloy welding combined blank × (0.4-0.8)min / mm.

[0030] Preferably, in step (6), the annealing conditions are as follows: the annealing temperature is 700-800℃, the time is 1-4h, and the cooling method is air cooling.

[0031] Preferably, in step (4), before the assembly, the TC4 alloy blank and the Ti2AlNb alloy outer ring blank obtained in step (3) are cleaned and dried.

[0032] Preferably, in step (4), after the diffusion welding, inert gas is introduced for cooling to below 200℃, the blank is discharged, and then the external sleeve-type welding tool is removed.

[0033] The application provides a preparation method of a Ti2AlNb / TC4 double-alloy disc. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

[0035] Figure 1 It is a structure size diagram of a target Ti2AlNb / TC4 double-alloy disc in the embodiment 1 of the present application.

[0036] Figure 2 It is a structure size diagram of a forging structure designed in the step (1) in the embodiment 1 of the present application.

[0037] Figure 3 It is a structure size diagram of a forging preform designed in the step (1) in the embodiment 1 of the present application.

[0038] Figure 4 It is a schematic diagram of a forging process simulated in the step (1) in the embodiment 1 of the present application.

[0039] Figure 5 It is a structure size diagram of a sleeve type welding tool in the step (2) in the embodiment 1 of the present application.

[0040] Figure 6 It is a microstructure morphology diagram of a double-alloy interface obtained in the step (4) in the embodiment 1 of the present application.

[0041] Figure 7 Microstructure morphology of the dual-alloy interface obtained in step (6) of Example 1 of the present application. DETAILED DESCRIPTION

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0043] Herein, in the technical features described in an open-ended manner, both the closed technical solution consisting of the listed features and the open technical solution containing the listed features are included.

[0044] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0045] Herein, in relation to numerical intervals, unless otherwise specified, the numerical intervals are considered to be continuous, and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood as including any and all sub-ranges subsumed therein.

[0046] Herein, in relation to data ranges, if only the unit is provided after the right end point, it means that the units of the left end point and the right end point are the same. For example, 50-80°C means that the units of the left end point "50" and the right end point "80" are both °C.

[0047] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, as can any upper limit with any other upper limit. In addition, each individual disclosed point or single numerical value can itself be combined as a lower limit or an upper limit with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recited.

[0048] The present application provides a preparation method of a Ti2AlNb / TC4 dual-alloy disc, comprising the following steps:

[0049] (1) Dual-alloy welding combined structure design:

[0050] According to the structure size of the Ti2AlNb / TC4 dual-alloy disc, the matching design of the dual-alloy welding combined blank structure and the forging structure is carried out in combination with numerical simulation.

[0051] The double-alloy welded combined blank is a combined structure of a Ti2AlNb alloy outer ring blank and a TC4 alloy inner ring blank, or a combined structure of a Ti2AlNb alloy outer ring blank and a TC4 alloy inner circular platform blank;

[0052] (2) Design and processing of welding tooling and forging die:

[0053] According to the structure design of the double-alloy welded combined blank determined in step (1), a high-temperature alloy ring-type welding tooling is designed and processed, and according to the structure of the forging determined in step (1), a forging die is designed and processed;

[0054] (3) Preparation and processing of double-alloy fine-grained blank:

[0055] The TC4 alloy is repeatedly upset forged to obtain a fine-grained blank, and then machined according to the size of the TC4 alloy inner ring blank / TC4 alloy inner circular platform blank to obtain a TC4 alloy blank; the Ti2AlNb alloy is repeatedly upset forged and punched to obtain a fine-grained ring blank, and after deformation, the Ti2AlNb alloy outer ring blank is machined according to the size of the Ti2AlNb alloy outer ring blank to obtain a Ti2AlNb alloy outer ring blank;

[0056] (4) Double-alloy diffusion welding:

[0057] The TC4 alloy blank and the Ti2AlNb alloy outer ring blank are assembled, then the preheated ring-type welding tooling is installed outside the Ti2AlNb alloy outer ring blank, and then placed in a vacuum diffusion welding furnace for diffusion welding, and then the external ring-type welding tooling is removed to obtain a double-alloy welded combined blank;

[0058] (5) Forging shaping:

[0059] The double-alloy welded combined blank obtained in step (4) is preheated, and then placed in the forging die designed in step (2) for forging shaping, and then air-cooled after forging to obtain a double-alloy disc forging;

[0060] (6) Heat treatment:

[0061] The double-alloy disc forging is annealed;

[0062] (7) Processing:

[0063] The double-alloy disc forging obtained in step (6) is machined by turning to obtain a double-alloy disc piece.

[0064] The Ti2AlNb / TC4 bialloy disk preparation method provided by this invention addresses the challenges of metallurgical defects and overheated structures in the interface bonding region of bialloy disks prepared by processes such as high-energy beam welding (+forging) and inertial friction welding (+forging). This method involves designing and machining a tapered annular mating surface of the bialloy to convert axial loading force into radial welding force. Based on this, a fine-grained billet is prepared to promote the diffusion fusion of dissimilar alloy components through grain boundaries during the welding process. The bialloy welded assembly billet is then forged and shaped to control the morphology and position of the bialloy interface. Furthermore, grain boundary slip and dislocation "channels" are utilized to promote the fusion of dissimilar alloy components in the interface bonding region, thereby improving performance. The method includes the following steps: bialloy welded assembly structure design, welding tooling and forging die design and machining, bialloy billet preparation and machining, bialloy diffusion welding, forging and shaping, heat treatment, and machining. The Ti2AlNb / TC4 bialloy disk prepared using this invention exhibits a metallurgical bonding region free of metallurgical defects and overheating structures. The interface region shows sufficient component diffusion, and the interface morphology and position are controllable, thus solving the problem of "weak bonding" at the bialloy interface. This invention can be used to prepare aero-engine compressor disks, meeting the requirements for tailoring performance and weight reduction.

[0065] Regarding step (1): Design of bialloy welded composite structure

[0066] According to this invention, based on the structural dimensions of the Ti2AlNb / TC4 bialloy disk, the matching design of the bialloy welded composite billet (i.e., forged preform) structure and the forging structure is carried out through numerical simulation. Specifically, based on the target structural dimensions of the Ti2AlNb / TC4 bialloy disk, the matching design of the bialloy welded composite billet (i.e., forged preform) structure and the forging structure is performed through numerical simulation.

[0067] In this invention, the dual-alloy welded composite billet is a combination structure of a Ti2AlNb alloy outer ring billet and a TC4 alloy inner ring billet, or a combination structure of a Ti2AlNb alloy outer ring billet and a TC4 alloy inner frustum billet.

[0068] In this invention, the bi-alloy welding interface in the bi-alloy welded composite billet (i.e., the forged preform) forms an angle of 10° to 30° with the axis, specifically 10°, 15°, 20°, 25°, or 30°. In this invention, the matching design of the bi-alloy welded composite billet (i.e., the forged preform) structure and the forging structure should ensure that the bi-alloy interface is parallel to the forging axis at the end of the subsequent forging and shaping step (5).

[0069] Regarding step (2): Design and processing of welding fixtures and forging dies

[0070] According to the present application, the high-temperature alloy collar-type welding tool is designed according to the structure of the double-alloy welding combination blank (i.e. the forging preform) determined in step (1). In the present application, the designed collar-type welding tool should be able to fit with the Ti2AlNb alloy outer ring blank in an interference fit to clamp the double-alloy welding blank.

[0071] According to the present application, the forging die is also designed according to the structure of the forging determined in step (1).

[0072] Regarding step (3): preparation and processing of the double-alloy fine-grain blank

[0073] In the present application, the TC4 alloy is repeatedly upset to obtain a fine-grain blank. The upsetting temperature is T β - (50-80) ℃, i.e. T β - (50-80) ℃, wherein T β is the phase transition point of the TC4 alloy; the upsetting temperature can be specifically T β - 50 ℃, T β - 55 ℃, T β - 60 ℃, T β - 65 ℃, T β - 70 ℃, T β - 75 ℃, T β - 80 ℃.

[0074] After the upsetting is completed, the TC4 alloy inner ring blank / TC4 alloy round table blank is machined according to the size. In the machining, the outer conical surface machining tolerance is preferably controlled to be +0.5 mm to +1.0 mm, and the surface roughness Ra is ≤1.6 μm. After the machining, the TC4 alloy blank is obtained.

[0075] In the present application, the Ti2AlNb alloy is also repeatedly upset and punched to obtain a fine-grain ring blank. The deformation temperature of the deformation process of the repeated upsetting is located in the lower part of the (α2+B2+O) three-phase region.

[0076] After the deformation is completed, the Ti2AlNb alloy outer ring blank is machined according to the size. In the machining, the inner conical surface machining tolerance is preferably controlled to be -1.0 mm to -0.5 mm, and the surface roughness Ra is ≤1.6 μm. After the machining, the Ti2AlNb alloy outer ring blank is obtained.

[0077] Regarding step (4): double-alloy diffusion welding

[0078] In the present application, the TC4 alloy blank and the Ti2AlNb alloy outer ring blank obtained in step (3) are preferably cleaned and dried in advance. The cleaning agent used in the cleaning is preferably acetone.

[0079] In the present application, after the above cleaning and drying, the TC4 alloy blank and the Ti2AlNb alloy outer ring blank are assembled, then the preheated sleeve type welding tool is installed outside the Ti2AlNb alloy outer ring blank to form the interference fit pre-tightening force after subsequent cooling. The preheating temperature of the sleeve type welding tool is preferably 150-500℃.

[0080] In the present application, after the above assembly and installation, the welded blank and the installed welding tool are subjected to diffusion welding in a vacuum diffusion welding furnace. In the present application, the diffusion welding conditions are preferably: welding temperature T β -(50-80)℃, pressure 10-20MPa, holding time 1-4h. The welding temperature can be specifically T β -50℃, T β -55℃, T β -60℃, T β -65℃, T β -70℃, T β -75℃, T β -80℃. The pressure can be specifically 10MPa, 15MPa, 20MPa. The holding time can be specifically 1h, 2h, 3h, 4h.

[0081] In the present application, after the above welding, air cooling to below 200℃, discharging, and then removing the external sleeve type welding tool, a double-alloy welded assembly blank is obtained.

[0082] Regarding step (5): forging shaping

[0083] In the present application, the double-alloy welded assembly blank obtained in step (4) is preheated and then placed in the forging die designed in step (2) for forging shaping.

[0084] The preheating temperature is preferably T β -(15-50)℃, specifically T β -15℃, T β -20℃, T β -25℃, T β -30℃, T β -35℃, T β -40℃, T β -45℃, T β -50℃. The preheating time is preferably calculated according to the maximum cross-sectional thickness δ max ×(0.4-08)min / mm, i.e. the maximum cross-sectional thickness δ max is multiplied by (0.4-08).

[0085] In this invention, after the forging and shaping process described above, the material is air-cooled to obtain a bialloy disc forging.

[0086] Regarding step (6): heat treatment

[0087] In this invention, the bialloy disc forging obtained in step (5) is subjected to annealing treatment. The preferred annealing conditions are: annealing temperature of 700–800°C, time of 1–4 hours, followed by air cooling. Specifically, the annealing temperature can be 700°C, 750°C, or 800°C. The annealing time can be 1 hour, 2 hours, 3 hours, or 4 hours.

[0088] Regarding step (7): processing

[0089] In this invention, after the heat treatment in step (6) is completed, the bialloy disc forging obtained in step (6) is machined into a bialloy disc by turning.

[0090] The method for preparing a Ti2AlNb / TC4 bialloy disk provided by this invention includes the design of a bialloy welded assembly structure, the design and processing of welding fixtures and forging dies, the preparation and processing of a fine-grained bialloy billet, bialloy diffusion welding, forging and shaping, heat treatment, and machining; the specific operation process is as described above. This invention first designs and processes a tapered annular mating surface of the bialloy to convert axial loading force into radial welding force. Based on this, a fine-grained billet is prepared to promote the diffusion and fusion of dissimilar alloy components through grain boundaries during the welding process. Then, the bialloy welded assembly billet is forged and shaped. While achieving control over the morphology and position of the bialloy interface, the grain boundary slip and dislocation "channels" during the forging process promote the fusion of dissimilar alloy components in the interface bonding region, thereby improving the interface performance level.

[0091] In the preparation process of this invention, the coordination of the preceding and following operations avoids welding defects such as porosity and microcracks during diffusion welding, and there is no heat-affected zone on both sides of the weld, so the defects and microstructure properties can be well controlled. After diffusion welding and forging deformation of fine-grained billets, the dissimilar components on both sides of the interface diffuse sufficiently, and the width of the bi-alloy diffusion layer increases. This is beneficial to improving the strength, plasticity, toughness and other indicators of the interface bonding zone during use, and is beneficial to the relaxation of thermal stress and load stress during use, avoiding cracking failure caused by local stress concentration. The bi-alloy interface obtained by forging and shaping is parallel and straight to the axis of the forging, and the interface morphology and position are controllable, which is conducive to maximizing the shearing performance.

[0092] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0093] Example 1

[0094] The target structural dimensions of the Ti2AlNb / TC4 bimetallic disk are: Φ372mm × 122mm (reference position for the connection interface: Φ272mm ± 10mm). Figure 1 As shown.

[0095] (1) Design of bi-alloy welded composite structure:

[0096] Based on the target structural dimensions of the Ti2AlNb / TC4 bialloy disk, the matching design of the bialloy welded composite billet (i.e., forged preform) structure and the forging structure was carried out using numerical simulation. The designed forging structure dimensions are as follows: Figure 2 As shown, the structural dimensions of the bialloy welded composite billet (i.e., the forged preform) are as follows: Figure 3 As shown, in the bialloy welded composite billet (i.e., the forged preform), the bialloy weld interface forms a 15° angle with the axis. The numerical simulation of the forging process is as follows: Figure 4 As shown.

[0097] (2) Design and fabrication of welding fixtures and forging dies:

[0098] Based on the structure of the bi-alloy welded composite billet (i.e., the forged precast billet) determined in step (1), design and process the high-temperature alloy collar-type welding fixture, such as... Figure 5 As shown. The forging die is designed and processed based on the forging structure determined in step (1).

[0099] (3) Preparation and processing of fine-grained bialloy billets

[0100] In T β The TC4 alloy was subjected to three upsetting and three drawing processes at -65℃ to obtain a fine-grained billet. Then, it was machined according to the dimensions of the TC4 alloy frustum billet, with the machining tolerance of the outer conical surface controlled at +0.5mm to +1.0mm and the surface roughness Ra1.6μm.

[0101] The Ti2AlNb alloy was subjected to three upsetting and three drawing processes and punching at 950℃ (lower part of the α2+B2+O phase region) to obtain a fine-grained ring blank. Then, the outer ring blank of the Ti2AlNb alloy was machined according to the dimensions, and the machining tolerance of the inner conical surface was controlled to be -1.0mm to -0.5mm, and the surface roughness Ra was 1.6μm.

[0102] (4) Bialloy diffusion welding

[0103] The surface of the dual-alloy fine-grained billet obtained in step (3) was cleaned with acetone and then dried. Next, the TC4 alloy billet and the Ti2AlNb alloy outer ring billet were assembled. Then, a preheated collar-type welding fixture was installed on the outside of the Ti2AlNb alloy outer ring billet to create an interference fit preload after subsequent cooling. Afterward, diffusion welding was performed in a vacuum diffusion welding furnace, with the following diffusion welding conditions controlled: welding temperature T... β-65℃, pressure 15MPa, pressure holding time 2h. After the completion of welding, argon was introduced to cool to below 200℃, and the furnace was discharged. Then, the outer sleeve type welding tooling was removed to obtain the double-alloy welded assembly blank.

[0104] (5) Forging shaping

[0105] The double-alloy welded assembly blank obtained in step (4) was preheated, and the preheating temperature T β -30℃, preheating time 100min. Then, it was placed in the forging die designed in step (2) for forging shaping. After forging, it was air-cooled to obtain the double-alloy forged disc.

[0106] (6) Heat treatment

[0107] The double-alloy forged disc obtained in step (5) was subjected to annealing treatment under the conditions of temperature 750℃, time 2h, and air cooling.

[0108] (7) Machining

[0109] The double-alloy forged disc obtained in step (6) was machined into a double-alloy disc piece by turning.

[0110] The microstructure of the double-alloy interface of the double-alloy welded assembly blank obtained in step (4) and the double-alloy forged disc obtained in step (6) was characterized, and the results are shown in Figures 6-7 wherein, Figure 6 is the microstructure morphology diagram of the double-alloy interface obtained in step (4), Figure 7 is the microstructure morphology diagram of the double-alloy interface obtained in step (6). As can be seen from the above two diagrams, after diffusion welding, the double alloy realizes defect-free diffusion bonding at the interface. After forging shaping and heat treatment, the width of the diffusion bonding layer increases significantly, indicating that forging deformation and heat treatment further promote the diffusion bonding of the double-alloy interface bonding zone, and improve the quality of the double-alloy interface connection.

[0111] The principles and implementations of the present application are described herein with specific examples, and the above descriptions of the examples are only used to help understand the method of the present application and its core ideas, including the best mode, and also enable any person skilled in the art to practice the present application, including manufacturing and using any device or system, and implementing any combined method. It should be noted that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The scope of patent protection of the present application is defined by the claims, and can include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the literal expressions of the claims, or if they include equivalent structural elements that are not substantially different from the literal expressions of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing a Ti2AlNb / TC4 dual alloy disk, characterized in that, Includes the following steps: (1) Design of bialloy welded composite structure: Based on the structural dimensions of the Ti2AlNb / TC4 bialloy disk, the matching design of the bialloy welded composite billet structure and the forging structure is carried out by combining numerical simulation. The dual-alloy welded composite billet is a combination structure of a Ti2AlNb alloy outer ring billet and a TC4 alloy inner ring billet, or a combination structure of a Ti2AlNb alloy outer ring billet and a TC4 alloy inner frustum billet. The bi-alloy welding interface in the bi-alloy welded composite billet forms an angle of 10° to 30° with the axis. The matching design of the bialloy welded composite billet structure and the forging structure ensures that the bialloy interface is parallel to the forging axis at the end of the subsequent forging and shaping step (5). (2) Design and fabrication of welding fixtures and forging dies: Based on the design and processing of the high-temperature alloy collar welding fixture according to the structure of the double alloy welded composite billet determined in step (1), and based on the design and processing of the forging die according to the structure of the forging determined in step (1); (3) Preparation and processing of fine-grained bialloy billets: A fine-grained billet of TC4 alloy is obtained by repeated upsetting and forging. Then, it is machined according to the dimensions of the inner ring billet / inner frustum billet of TC4 alloy to obtain the TC4 alloy billet. A fine-grained ring billet of Ti2AlNb alloy is obtained by repeated upsetting and forging and punching. After deformation, it is machined according to the dimensions of the outer ring billet of Ti2AlNb alloy to obtain the outer ring billet of Ti2AlNb alloy. The upsetting temperature of the TC4 alloy is T. β -(50~80)℃, where T β The phase transformation point of TC4 alloy; The deformation temperature of the Ti2AlNb alloy is located in the lower part of the (α2+B2+O) phase region; (4) Bialloy diffusion welding: The TC4 alloy billet and the Ti2AlNb alloy outer ring billet are assembled, and then a preheated collar-type welding fixture is installed on the outside of the Ti2AlNb alloy outer ring billet. Then, it is placed in a vacuum diffusion welding furnace for diffusion welding. After that, the outer collar-type welding fixture is removed to obtain a bi-alloy welded composite billet. The conditions for diffusion welding are: welding temperature T β - (50~80)℃, pressure 10~20MPa, pressure holding time 1~4h; (5) Forging and shaping: The bialloy welded composite billet obtained in step (4) is preheated and then placed into the forging mold designed in step (2) for forging and shaping. After forging, it is air-cooled to obtain a bialloy disc forging. (6) Heat treatment: The bialloy disc forging is annealed. The annealing conditions are: annealing temperature 700~800℃, time 1~4h, air cooling; (7) Processing: The bialloy forged disc obtained in step (6) is machined by turning to obtain the bialloy disc part.

2. The preparation method according to claim 1, characterized in that, The collar-type welding fixture designed in step (2) is interference-fitted with the Ti2AlNb alloy outer ring blank.

3. The preparation method according to claim 1, characterized in that, In step (3), the machining tolerance of the outer conical surface of the TC4 alloy after machining is +0.5mm~+1.0mm, and the surface roughness Ra≤1.6μm; The machining tolerance of the inner conical surface of the Ti2AlNb alloy after machining is -1.0mm to -0.5mm, and the surface roughness Ra≤1.6μm.

4. The preparation method according to claim 1, characterized in that, In step (5), the preheating temperature is T. β -(15~50)℃; the preheating time is based on the maximum cross-sectional thickness δ of the bialloy welded composite billet. max Calculated as × (0.4~08) min / mm.

5. The preparation method according to claim 1, characterized in that, In step (4), before the assembly, the TC4 alloy billet and Ti2AlNb alloy outer ring billet obtained in step (3) are cleaned and dried.

6. The preparation method according to claim 1, characterized in that, In step (4), after the diffusion welding, an inert gas is introduced to cool the temperature to below 200°C, and the furnace is removed. Then, the external collar welding fixture is removed.

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