Method for welding ti 2alnb-based alloy

Abstract

The present invention belongs to the technical field of welding, and particularly relates to a method for welding a Ti2AlNb-based alloy. Provided in the present invention is a method for welding a Ti2AlNb-based alloy. The method comprises the following steps: subjecting a Ti2AlNb-based alloy to solution treatment, so as to obtain a Ti2AlNb-based alloy in a solid solution state; welding the Ti2AlNb-based alloy in the solid solution state, so as to obtain a welded Ti2AlNb-based alloy; and maintaining the temperature of the welded Ti2AlNb-based alloy, and then sequentially subjecting same to first aging heat treatment and second aging heat treatment, so as to obtain a solder alloy. By means of the welding method provided by the present invention, the structure type and distribution state of a welding joint and a base metal are optimized while the residual stress of the welding joint is eliminated, thereby effectively improving the strength performance of an inertia friction welding assembly of the Ti2AlNb-based alloy.

Description

A welding method for Ti2AlNb-based alloy

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on July 24, 2023, with application number CN202310904568.5 and invention name “A welding method for Ti2AlNb-based alloys”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The invention belongs to the technical field of welding, and in particular relates to a welding method for a Ti2AlNb-based alloy. Background Art

[0003] In recent years, the performance improvements of the world's advanced aircraft engines have primarily relied on new materials and processes. As highly complex and sophisticated thermal machines, aircraft engines require materials that operate in extremely complex environments, such as high temperatures, high pressures, and high speeds. This closely links the development of high-thrust-to-weight ratio aircraft engines with the application of high-temperature structural materials. Furthermore, the engines must be lightweight, long-lasting, and reusable. Therefore, the development and manufacture of high-thrust-to-weight ratio aircraft engines place stringent demands on both the materials used and the processing and manufacturing technologies.

[0004] With advancements in aviation manufacturing technology, high thrust-to-weight ratio aero-engine structures are moving toward lightweighting, structural integration, and composite materials. Currently, advanced welding technology is one of the most effective methods for achieving integrated engine components. Furthermore, lightweighting materials, combined with advanced welding techniques, can further reduce aero-engine weight and improve thrust-to-weight ratios. Intermetallic compounds, in particular, have attracted widespread attention, particularly in the aviation sector, due to their superior properties, such as heat resistance, high specific strength, high specific life, high thermal conductivity, and high oxidation resistance of high-temperature alloys, combined with the toughness and good hot workability of ceramic materials.

[0005] Ti2AlNb-based alloys are a new type of lightweight, high-temperature-resistant structural material in the Ti-Al alloy system with a high Nb content, developed following the development of Ti3Al and TiAl alloys. Their microstructure is characterized by a composite structure dominated by O phase, with B2 and α2 phases as auxiliary phases. The long-range, ordered orthorhombic lattice structure of the O phase weakens dislocation motion and prevents crack propagation, resulting in high specific strength and stiffness, excellent fracture toughness, and high-temperature creep resistance. The alloy can safely operate in the temperature range of 650-750°C, meeting the extremely high material performance requirements for the cold and hot end components of high thrust-to-weight ratio aircraft engines. It is considered an ideal lightweight, high-temperature-resistant structural material that can help further enhance engine performance through structural weight reduction.

[0006] As an advanced solid-phase welding technology, inertia friction welding (IFW) features a limited number of process control parameters, low heat input, minimal deformation, and narrow weld seams. It is one of the few processes that can truly achieve 6σ quality levels, making it particularly suitable for welding dissimilar materials, such as powder metallurgy alloys and high-temperature alloys. However, the welded joints can still exhibit significant residual stresses, resulting in lower joint strength. Because Ti2AlNb-based alloys possess both high specific strength and the hard and brittle properties of intermetallic compounds, even with optimal IFW process parameters, significant residual stresses can still occur, reducing the strength of the welded joints.

[0007] Summary of the Invention

[0008] The object of the present invention is to provide a Ti2AlNb-based alloy welding method, which can improve the strength of the Ti2AlNb-based alloy welded joint.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] The present invention provides a welding method for a Ti2AlNb-based alloy, comprising the following steps:

[0011] The Ti2AlNb-based alloy is subjected to a solid solution treatment to obtain a Ti2AlNb-based alloy in a solid solution state;

[0012] Welding the Ti2AlNb-based alloy in a solid solution state to obtain a welded Ti2AlNb-based alloy;

[0013] The welded Ti2AlNb-based alloy is subjected to a heat preservation treatment, a first aging heat treatment and a second aging heat treatment in sequence to obtain a welded alloy.

[0014] Preferably, the atomic percentage of Al in the Ti2AlNb-based alloy is 18-30%, and the atomic percentage of Nb is 12.5-30%.

[0015] Preferably, the temperature of the solution treatment is 850-950° C., and the holding time is 30 minutes.

[0016] Preferably, after the solution treatment, the obtained alloy is further water-cooled.

[0017] Preferably, the welding method is inertia friction welding.

[0018] Preferably, the inertia friction welding parameters are: rotation speed of 500 rpm, inertia of 165 kg·m 2 , the pressure is 60MPa.

[0019] Preferably, the temperature of the heat preservation treatment is 680-720° C., and the heat preservation time is 50-70 minutes.

[0020] Preferably, after the heat preservation treatment, the obtained alloy is further cooled to room temperature.

[0021] Preferably, the temperature of the first aging heat treatment is 980-1000° C., and the holding time is 100-120 minutes.

[0022] Preferably, the time for heating from room temperature to the first aging heat treatment temperature is 90 to 110 minutes.

[0023] Preferably, after the first aging heat treatment, the obtained alloy is cooled to room temperature.

[0024] Preferably, the temperature of the second aging heat treatment is 780-800° C., and the holding time is 1420-1450 min.

[0025] Preferably, the time for heating from room temperature to the second aging heat treatment temperature is 70 to 90 minutes.

[0026] Preferably, the first aging heat treatment and the second aging heat treatment are both performed under vacuum conditions.

[0027] The present invention provides a welding method for a Ti2AlNb-based alloy, comprising the following steps: subjecting the Ti2AlNb-based alloy to a solution treatment to obtain a Ti2AlNb-based alloy in a solution state; welding the Ti2AlNb-based alloy in a solution state to obtain a welded Ti2AlNb-based alloy; and sequentially subjecting the welded Ti2AlNb-based alloy to a heat preservation treatment, a first aging heat treatment, and a second aging heat treatment to obtain a welded alloy. The welding method provided by the present invention eliminates residual stress in the weld joint while optimizing the microstructure and distribution of the O phase, α2 phase, and B2 phase in the weld joint and the base material, thereby effectively improving the strength performance of the Ti2AlNb-based alloy inertia friction welding assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a microstructure diagram of a Ti-20Al-25Nb alloy in a solid solution state in Example 1;

[0029] FIG2 is a microstructure diagram of the base material in the welding alloy obtained in Example 1;

[0030] FIG3 is a microstructure diagram of the weld joint in the weld alloy obtained in Example 1;

[0031] FIG4 is a test specimen of the welded alloy obtained in Example 1 after being stretched at room temperature;

[0032] FIG5 is a test specimen of the welding alloy obtained in Example 1 after being stretched at a high temperature of 650° C.;

[0033] FIG6 is a schematic flow chart of the welding method in Example 1. DETAILED DESCRIPTION

[0034] The present invention provides a welding method for a Ti2AlNb-based alloy, comprising the following steps:

[0035] The Ti2AlNb-based alloy is subjected to a solid solution treatment to obtain a Ti2AlNb-based alloy in a solid solution state;

[0036] Welding the Ti2AlNb-based alloy in a solid solution state to obtain a welded Ti2AlNb-based alloy;

[0037] The welded Ti2AlNb-based alloy is subjected to a heat preservation treatment, a first aging heat treatment and a second aging heat treatment in sequence to obtain a welded alloy.

[0038] The present invention performs solid solution treatment on the Ti2AlNb-based alloy to obtain the Ti2AlNb-based alloy in a solid solution state.

[0039] In the present invention, the atomic percentage of Al in the Ti2AlNb-based alloy is preferably 18 to 30%, more preferably 21 to 27%, and more preferably 22 to 25%; the atomic percentage of Nb is 12.5 to 30%, more preferably 15 to 27%, more preferably 17 to 25%, and most preferably 22 to 23%. In the present invention, the Ti2AlNb-based alloy preferably includes a Ti-25Al-17Nb type alloy, a Ti-21Al-22Nb type alloy, a Ti-22Al-23Nb type alloy, a Ti-22Al-25Nb type alloy, or a Ti-22Al-27Nb type alloy (wherein the numbers represent atomic percentages).

[0040] In the present invention, the temperature of the solution treatment is preferably 850-950°C, more preferably 880-920°C, and even more preferably 890-900°C, and the holding time is preferably 30 minutes. After the solution treatment, the present invention further preferably includes water cooling the obtained alloy.

[0041] After obtaining the Ti2AlNb-based alloy in a solid solution state, the present invention welds the Ti2AlNb-based alloy in a solid solution state to obtain the welded Ti2AlNb-based alloy.

[0042] Before performing the welding, the present invention also preferably includes pre-treating the Ti2AlNb-based alloy in a solid solution state; the pre-treatment preferably includes: turning the end face of the Ti2AlNb-based alloy in a solid solution state to make the end face show metallic luster, then wiping the end face with alcohol or acetone to remove coolant and oil stains and then drying it.

[0043] In the present invention, the welding method is preferably inertia friction welding. In the present invention, the inertia friction welding condition parameters are preferably: a rotation speed of 500 rpm, an inertia of 165 kg·m 2 In a specific embodiment of the present invention, the inertia friction welding process preferably includes: clamping the pretreated alloy on the main shaft rotating side and the tailstock moving side of the inertia friction welding machine respectively, and performing inertia friction welding.

[0044] After obtaining the welded Ti2AlNb-based alloy, the present invention sequentially performs a heat preservation treatment, a first aging heat treatment, and a second aging heat treatment on the welded Ti2AlNb-based alloy to obtain a welded alloy.

[0045] In the present invention, the temperature of the heat preservation treatment is preferably 680-720°C, more preferably 700°C; the heat preservation time is preferably 50-70 minutes, more preferably 60 minutes. In the present invention, the heat preservation treatment is preferably carried out in a heat treatment furnace.

[0046] After the heat preservation treatment, the present invention preferably further comprises cooling the obtained alloy to room temperature; after cooling to room temperature, it preferably further comprises removing welding burrs on the inner and outer sides of the alloy until the weld joint is smooth and exhibits metallic luster.

[0047] In the present invention, the temperature of the first aging heat treatment is preferably 980-1000°C, more preferably 985-990°C; the time for heating from room temperature to the first aging heat treatment temperature is preferably 90-110 minutes, more preferably 100 minutes; and the holding time is preferably 100-120 minutes, more preferably 110 minutes. In the present invention, the first aging heat treatment is preferably performed under vacuum conditions. In the present invention, the first aging heat treatment is preferably performed in a vacuum heat treatment furnace.

[0048] After the first aging heat treatment, the present invention further preferably includes cooling the obtained alloy to room temperature; the cooling method is preferably air cooling or cooling under atmosphere.

[0049] In the present invention, the temperature of the second aging heat treatment is preferably 780-800°C, more preferably 785-790°C; the time for heating from room temperature to the second aging heat treatment temperature is preferably 70-90 minutes, more preferably 80 minutes; and the holding time is preferably 1420-1450 minutes, more preferably 1430-1440 minutes. In the present invention, the second aging heat treatment is preferably performed under vacuum conditions. In the present invention, the second aging heat treatment is preferably performed in a vacuum heat treatment furnace.

[0050] After the second aging heat treatment, the present invention further preferably includes cooling the obtained alloy to room temperature; the cooling method is preferably air cooling or cooling under atmosphere.

[0051] In order to further illustrate the present invention, a welding method for a Ti2AlNb-based alloy provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] The Ti-20Al-25Nb alloy was solution treated at 900°C for 30 minutes and then water-cooled to obtain a Ti-20Al-25Nb alloy in a solid solution state.

[0054] The end face of the obtained Ti-20Al-25Nb alloy in a solid solution state is turned until the end face exhibits metallic luster, and then the end face is wiped with alcohol to remove coolant and oil stains on the end face and then dried;

[0055] The pretreated Ti-20Al-25Nb alloy was clamped to the main shaft rotating side and tailstock moving side of the inertia friction welding machine respectively, and inertia friction welding was performed to obtain the welded Ti-20Al-25Nb alloy. The inertia friction welding parameters were: rotation speed of 500 rpm, inertia of 165 kg·m 2 , pressure is 60MPa,;

[0056] The obtained welded Ti-20Al-25Nb alloy was placed in a heat treatment furnace at 700°C for 60 minutes, then taken out and cooled to room temperature. After cooling, the weld flash on the inner and outer sides of the alloy was removed until the weld joint was smooth and had a metallic luster.

[0057] The welded alloy is placed in a vacuum heat treatment furnace for a first aging heat treatment. The first aging heat treatment temperature is 1000°C, the holding time is 120 minutes, and the heating time from room temperature to 1000°C is 100 minutes. After the first aging heat treatment is completed, the alloy is air-cooled to room temperature.

[0058] The cooled alloy was again placed in a vacuum heat treatment furnace for a second aging heat treatment. The second aging heat treatment temperature was 790°C, the holding time was 1450 min, and the heating time from room temperature to 790°C was 80 min. After the second aging heat treatment was completed, it was air-cooled to room temperature to obtain a welding alloy.

[0059] Performance Testing

[0060] Test Example 1

[0061] FIG1 is a microstructure diagram of the Ti-20Al-25Nb alloy in a solid solution state in Example 1; FIG2 is a microstructure diagram of the base material in the weld alloy in Example 1; FIG3 is a microstructure diagram of the weld joint in the weld alloy in Example 1;

[0062] As can be seen from Figure 1, the microstructure of the Ti-20Al-25Nb alloy parent material in the solid solution state is composed of α2 phase, B2 phase and O phase. The α2 phase is discontinuously distributed at the grain boundaries of the original B2 phase in an approximately equiaxed shape, and the O phase is dispersed in the B2 phase matrix in a rod-like shape, parallel or cross-shaped.

[0063] As can be seen from Figure 2, after the Ti-20Al-25Nb alloy is subjected to solid solution and aging treatment, the microstructure of the base material is transformed into a two-phase structure of B2+O phase, and the O phase structure is equiaxed and blocky distributed on the B2 phase matrix;

[0064] As can be seen from Figure 3, the microstructure of the weld area after welding shows that the O phase structure precipitates along the equiaxed B2 phase grain boundaries and within the grains, presenting a continuous network structure at the grain boundaries and a block and needle-like structure within the grains.

[0065] Test Example 2

[0066] The tensile strength of the solder alloy obtained in Example 1 was tested at room temperature and at 650°C. The test results are shown in Table 1. FIG4 shows a tensile test specimen of the solder alloy obtained in Example 1 after being stretched at room temperature, and FIG5 shows a tensile test specimen of the solder alloy obtained in Example 1 after being stretched at 650°C.

[0067] Table 1 Tensile strength test results of the welding alloy obtained in Example 1

[0068] As can be seen from Table 1, the welding alloy obtained by the welding method provided by the present invention has excellent tensile strength properties at room temperature and at a high temperature of 650°C, which provides support for the application of Ti2AlNb-based alloy inertia friction welding assemblies in aircraft engine rotor assemblies.

[0069] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A welding method for Ti2AlNb-based alloy, characterized in that: The following steps are involved: The Ti2AlNb-based alloy is subjected to a solid solution treatment to obtain a Ti2AlNb-based alloy in a solid solution state; Welding the Ti2AlNb-based alloy in a solid solution state to obtain a welded Ti2AlNb-based alloy; The welded Ti2AlNb-based alloy is sequentially subjected to a heat preservation treatment, a first aging heat treatment and a second aging heat treatment to obtain a welding alloy.

2. The welding method according to claim 1, characterized in that: The atomic percentage of Al in the Ti2AlNb-based alloy is 18-30%, and the atomic percentage of Nb is 12.5-30%.

3. The welding method according to claim 1, characterized in that: The temperature of the solution treatment is 850-950° C., and the holding time is 30 minutes.

4. The welding method according to claim 3, characterized in that: After the solution treatment, the obtained alloy is water cooled.

5. The welding method according to claim 1, characterized in that: The welding method is inertia friction welding.

6. The welding method according to claim 5, characterized in that: The inertia friction welding conditions are: rotation speed of 500 rpm, inertia of 165 kg·m 2 , the pressure is 60MPa.

7. The welding method according to claim 1, characterized in that: The temperature of the heat preservation treatment is 680-720° C., and the heat preservation time is 50-70 minutes.

8. The welding method according to claim 7, characterized in that: After the heat preservation treatment, the obtained alloy is cooled to room temperature.

9. The welding method according to claim 1, characterized in that: The temperature of the first aging heat treatment is 980-1000° C., and the holding time is 100-120 minutes.

10. The welding method according to claim 9, characterized in that: The time for heating from room temperature to the first aging heat treatment temperature is 90 to 110 minutes.

11. The welding method according to claim 10, characterized in that: After the first aging heat treatment, the obtained alloy is cooled to room temperature.

12. The welding method according to claim 1, characterized in that: The temperature of the second aging heat treatment is 780-800° C., and the holding time is 1420-1450 min.

13. The welding method according to claim 12, characterized in that: The time for heating from room temperature to the second aging heat treatment temperature is 70 to 90 minutes.

14. The welding method according to any one of claims 1, 9 to 13, characterized in that: The first aging heat treatment and the second aging heat treatment are both performed under vacuum conditions.

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