Diffusion welding process for large-area hollow-structure Ti2AlNb alloy component

Abstract

The invention relates to the technical field of Ti2AlNb-based alloy welding, in particular to a diffusion welding process of a large-area hollow-structure Ti2AlNb alloy component, which comprises the following steps of: prefabricating a welding boss on a welding surface of a hollow reinforcing rib area of a part; the parts are assembled on a welding tool according to technological requirements; the welding tool and the part are put into a vacuum diffusion welding furnace, the temperature is increased to the first temperature, first pressure is applied, heat preservation is conducted for first preset time, then pressure is unloaded, the temperature is continuously increased to the second temperature, second pressure is applied, heat preservation is conducted for second preset time, then pressure is unloaded, and then the furnace temperature is reduced to the third temperature for aging treatment; and preserving heat for a third preset time and then cooling along with the furnace. The diffusion welding process of the large-area hollow-structure Ti2AlNb alloy component aims at solving the problem that the connection reliability of a hollow Ti2AlNb component with a complex welding section is poor.

Description

Technical Field

[0001] The present invention relates to Ti 2 The invention relates to the field of AlNb-based alloy welding technology, specifically to a large-area hollow structure Ti 2 Diffusion welding process of AlNb alloy components. Background Art

[0002] With the development of technology, aircraft and aero-engines have put forward higher requirements for structural materials. Lightweight and high efficiency have become the main development trend. At the same time, the service environment of components has become more severe, and the working temperature has reached above 700℃. Therefore, the design is based on the high temperature resistance and lightweight design concept. In terms of material selection, new lightweight and high temperature resistant materials are selected, and in terms of structure, a hollow multi-rib structure is designed to maximize the advantages of materials and structures, thereby improving the overall comprehensive performance of components.

[0003] Ti 2 AlNb alloy has low density, high specific strength, good high temperature oxidation resistance, its long-term working temperature reaches 600 ~ 800 ℃, and can withstand an instantaneous working temperature of more than 1000 ℃. At the same time, the density of Ti2AlNb alloy is only about 60% of that of high temperature alloy. 2 AlNb alloy has become a research hotspot for new materials and is considered to be the new material most likely to replace nickel-based high-temperature alloys in the aviation and aerospace fields in the future.

[0004] The reinforced structure is large in size, with a high hollow ratio, and the welding area of ​​the split diffusion welding reaches 10000mm 2 The cross-section of the half-blank to be welded is complex, the width of the hollow internal reinforcement area is about 2 mm, and the area to be welded in the mounting seat area is large (such as Figure 1 As shown), the force on the welded surface is uneven. 2 The AlNb alloy diffusion welding pressure is usually selected to be 20-40MPa. Applying a larger welding pressure may cause the reinforcing ribs to become unstable and collapse, while applying a smaller force will result in poor diffusion welding quality in the solid area of ​​the mounting seat. On the other hand, a larger welding area requires higher tonnage of diffusion welding equipment, so a larger tonnage diffusion welding equipment is required, which significantly increases the manufacturing cost.

[0005] Therefore, the inventor provides a large-area hollow structure Ti 2 Diffusion welding process of AlNb alloy components. Summary of the invention

[0006] (1) Technical issues to be solved

[0007] The embodiment of the present invention provides a large-area hollow structure Ti 2 The diffusion welding process of AlNb alloy components solves the problem of hollow Ti2 The technical problem is that the connection reliability of AlNb components is poor.

[0008] (2) Technical solution

[0009] The present invention provides a large-area hollow structure Ti 2 The diffusion welding process of AlNb alloy components includes the following steps:

[0010] Prefabricate welding bosses on the welding surface of the hollow rib area of ​​the part;

[0011] Assembling the parts on the welding tooling according to the process requirements;

[0012] The welding tool and the parts are placed in a vacuum diffusion welding furnace, the temperature is raised to a first temperature, a first pressure is applied, the first pressure is unloaded after being kept warm for a first preset time, the temperature is continued to be raised to a second temperature, a second pressure is applied, the second pressure is unloaded after being kept warm for a second preset time, and then the furnace temperature is lowered to a third temperature for aging treatment, and the furnace is cooled after being kept warm for a third preset time.

[0013] Furthermore, the height of the welding boss is h, and the total welding compression of the part is H, wherein h: H=1 / 20~1 / 10.

[0014] Furthermore, the first temperature is 950-990°C.

[0015] Furthermore, the first pressure is 20-40 MPa.

[0016] Furthermore, the first preset time is 1 to 2 hours.

[0017] Furthermore, the second temperature is 1020-1040°C.

[0018] Furthermore, the second pressure is 5-10 MPa.

[0019] Furthermore, the second preset time is 2 to 4 hours.

[0020] Furthermore, the third temperature is 760-800°C.

[0021] Furthermore, the third preset time is 8 to 16 hours.

[0022] (3) Beneficial effects

[0023] In summary, the present invention adds a welding station in the rib area to ensure that the rib area diffuses mutually and has a certain bearing capacity. At the same time, the pressure is applied and released twice during the diffusion welding process, so that a large area Ti 2High reliability manufacturing of AlNb alloy hollow structural parts reduces the requirements for equipment tonnage capacity for large-area diffusion welding, thereby greatly improving equipment utilization and reducing production costs. At the same time, it also ensures that the narrow reinforcement ribs do not become unstable during the welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a structural main view of a hollow structural member with a complex cross section;

[0026] Figure 2 yes Figure 1 AA surface structural section view;

[0027] Figure 3 A large-area hollow structure Ti provided by the embodiment of the present invention 2 Schematic diagram of the diffusion welding process of AlNb alloy components;

[0028] Figure 4 A large-area hollow structure Ti provided by the embodiment of the present invention 2 Schematic diagram of the structure of the welding boss of the AlNb alloy component;

[0029] Figure 5 A large-area hollow structure Ti provided by the embodiment of the present invention 2 Structural diagram of the total welding compression deformation of AlNb alloy components;

[0030] Figure 6 A large-area hollow structure Ti provided by the embodiment of the present invention 2 Temperature curve of the diffusion welding process of AlNb alloy components.

[0031] In the figure:

[0032] 1- Rib area; 2- Solid area; 3- Welding boss. DETAILED DESCRIPTION

[0033] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] Figure 3 A large-area hollow structure Ti provided by the embodiment of the present invention 2 Schematic diagram of the diffusion welding process of AlNb alloy components, see Figure 3 , the process may include the following steps:

[0037] S100. Prefabricate welding bosses on the welding surface of the hollow reinforcement area of ​​the part.

[0038] Specifically, Figures 4-5 As shown, according to the part digital model, the pre-welding processing is carried out. The welding surface of the hollow reinforcement area 1 needs to be prefabricated with a welding boss 3, and the solid area 2 does not need to be prefabricated with a welding boss 3. The height of the prefabricated single-sided welding boss 3 is h, and the total welding compression of the part is H, where h: H = 1 / 20 ~ 1 / 10. Before welding, the welding end surface is wiped clean with alcohol or acetone. In view of the welding characteristics of diffusion welding itself, a certain amount of compression deformation will be generated in the direction of applied pressure during welding. Let S be the actual height of the part after welding, S1 be the height of the single-sided part before welding, and H be the total welding compression deformation of the part, H = (2S1-S), h = (1 / 20 ~ 1 / 10)H.

[0039] S200. Assemble the parts on the welding tooling according to the process requirements.

[0040] Specifically, welding assembly involves assembling the split half-blanks to be welded according to the process requirements, ensuring that the welding ribs are aligned with each other, and coating solder resist between the parts and the tooling to prevent them from sticking to each other.

[0041] S300, placing the welding tooling and parts into a vacuum diffusion welding furnace, heating up to a first temperature, applying a first pressure, keeping the temperature for a first preset time, then unloading the first pressure, continuing to heat up to a second temperature, applying a second pressure, keeping the temperature for a second preset time, then unloading the second pressure, then lowering the furnace temperature to a third temperature for aging treatment, keeping the temperature for a third preset time, then cooling with the furnace.

[0042] Specifically, the first temperature is 950-990°C, the first pressure is 20-40 MPa, and the first preset time is 1-2 hours. The second temperature is 1020-1040°C, the second pressure is 5-10 MPa, and the second preset time is 2-4 hours. The third temperature is 760-800°C, and the third preset time is 8-16 hours.

[0043] It should be noted here that usually Ti 2 The welding temperature and pressure of AlNb alloy diffusion welding are 950~990℃ and 20~40MPa respectively. 2 +O+B2 three-phase region and α 2 +B2 two-phase region (close to the three-phase region transition temperature), the matrix has more O phase and α 2 Phase precipitation strengthening phase, the existence of the precipitated phase under external force conditions plays a pinning role on dislocation slip, so the matrix material has good deformation resistance at this temperature. A higher welding pressure needs to be applied during the diffusion welding process to ensure that the workpiece to be welded undergoes a certain plastic deformation and forms a good weld joint. However, for large-area, hollow, multi-rib structures, the larger the welding area, the greater the corresponding diffusion welding pressure, the higher the required diffusion welding equipment capacity, and the equipment capacity may be insufficient; at the same time, when the diffusion welding pressure is too high, due to the thin wall thickness of the rib area, deformation and instability are prone to occur under high welding pressure. Therefore, in this embodiment, a welding boss is prefabricated in the rib area, see Figure 6 In the first stage of welding (welding temperature 950-990℃, welding pressure 20-40MPa, insulation 1-2h), the material at the welding boss is consumed in the longitudinal compression deformation. At this time, the rib area has a certain strength to achieve reliable connection, the entire welding surface is in contact with each other, and the welding pressure is significantly reduced. Under this process condition, a good welding joint cannot be obtained in the solid area of ​​the mounting seat; at this time, the welding temperature is increased to 1020-1040℃, 5-10MPa pressure is applied, and the temperature is kept for 2-4h. In this temperature range, Ti 2 AlNb alloy is in B2+α 2 The two-phase region is close to the B2 single-phase region. At this time, the precipitated phase inside the grain and part of the grain boundary is dissolved into the matrix. Due to the reduction of the precipitated phase, the metal's deformation resistance is reduced. Therefore, under a smaller welding pressure, the matrix on both sides can be effectively deformed. At the same time, as the temperature increases, the element diffusion capacity increases, and finally a reliable connection of a complex hollow multi-rib structure can be achieved. In order to ensure the strength of the diffusion welding joint, an insulation step is set at 760-800℃. This area is the O+B2 two-phase region. During the insulation process, the O phase is precipitated at the grain boundary and inside the grain. The presence of the precipitated phase can improve the joint strength.

[0044] Example 1

[0045] Taking a certain aircraft component as an example, the above process method is used to achieve welding:

[0046] Step 1: Preparation before welding. Perform pre-welding processing according to the part drawing. The welding surface of the hollow reinforcement area needs to be prefabricated with a boss. The height of the prefabricated single-sided welding boss is 0.1mm. The total welding compression of the part is 1mm. Use alcohol or acetone to wipe the welding end surface clean before welding.

[0047] Step 2: Welding assembly: assemble the split half billets to be welded according to the process requirements to ensure that the welding ribs are aligned with each other;

[0048] Step 3: Vacuum diffusion welding: put the welding tooling and parts into the vacuum diffusion welding furnace, heat up to the part temperature of 980℃, apply 20MPa pressure, keep warm for 1h, unload the pressure, continue to heat up to 1020℃, apply 5MPa pressure, keep warm for 2h, unload the pressure, then reduce the furnace temperature to 800℃ for aging treatment, keep warm for 16 hours and cool with the furnace. The vacuum degree required during welding is 8×10 -3 Pa;

[0049] Step 4: Remove the tooling from the furnace. Since this process is routine, it will not be described in detail here.

[0050] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0051] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A large area hollow structure Ti 2 Diffusion welding process of AlNb alloy components, It is characterized in that The process includes the following steps: Prefabricate welding bosses on the welding surface of the hollow rib area of ​​the part; Assembling the parts on the welding tooling according to the process requirements; The welding tool and the parts are placed in a vacuum diffusion welding furnace, the temperature is raised to a first temperature, a first pressure is applied, the first pressure is unloaded after being kept warm for a first preset time, the temperature is continued to be raised to a second temperature, a second pressure is applied, the second pressure is unloaded after being kept warm for a second preset time, and then the furnace temperature is lowered to a third temperature for aging treatment, and the furnace is cooled after being kept warm for a third preset time.

2. The large-area hollow structure Ti according to claim 1 2 Diffusion welding process of AlNb alloy components, It is characterized in that The height of the welding boss is h, and the total welding compression of the part is H, where h: H=1 / 20~1 / 10.

3. The large-area hollow structure Ti according to claim 1 2 Diffusion welding process of AlNb alloy components, It is characterized in that The first temperature is 950-990°C.

4. The large-area hollow structure Ti according to claim 3 2 Diffusion welding process of AlNb alloy components, It is characterized in that The first pressure is 20-40 MPa.

5. The large-area hollow structure Ti according to claim 4 2 Diffusion welding process of AlNb alloy components, It is characterized in that The first preset time is 1 to 2 hours.

6. The large-area hollow structure Ti according to claim 1 2 Diffusion welding process of AlNb alloy components, It is characterized in that The second temperature is 1020-1040°C.

7. The large-area hollow structure Ti according to claim 6 2 Diffusion welding process of AlNb alloy components, It is characterized in that The second pressure is 5-10 MPa.

8. The large-area hollow structure Ti according to claim 7 2 Diffusion welding process of AlNb alloy components, It is characterized in that The second preset time is 2 to 4 hours.

9. The large-area hollow structure Ti according to claim 1 2 Diffusion welding process of AlNb alloy components, It is characterized in that The third temperature is 760-800°C.

10. The large-area hollow structure Ti according to claim 9 2 Diffusion welding process of AlNb alloy components, It is characterized in that The third preset time is 8 to 16 hours.

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