A lightweight, high-strength TiAlNbB multi-principal element alloy plate and its preparation method

Abstract

This invention belongs to the field of alloy material preparation, specifically relating to a lightweight, high-strength TiAlNbB multi-principal element alloy plate and its preparation method. Using a common metallurgical TiAlNbB multi-principal element alloy ingot as the billet, this invention prepares large-size TiAlNbB multi-principal element alloy plates with DP microstructure through hot isostatic pressing and direct cladding hot rolling. Then, a short-time electric pulse heat treatment process is used to prepare large-size TiAlNbB multi-principal element alloy plates with a uniform and fine NF structure.

Description

Technical Field

[0001] This invention belongs to the field of alloy material preparation, specifically relating to a lightweight, high-strength TiAlNbB multi-principal-element alloy plate and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Lightweight, high-strength TiAlNbB multi-principal element alloys, due to their low density and high specific strength and specific modulus of elasticity, maintain sufficiently high strength and stiffness at high temperatures. They also possess excellent creep and oxidation resistance, making them a highly competitive material for lightweight, heat-resistant structural components in aerospace, missile engines, and automobiles. Currently, research on cast TiAlNbB multi-principal element alloys has entered the industrial application stage, while wrought TiAlNbB multi-principal element alloy plates are one of the most important research directions in the field.

[0004] In engineering applications, obtaining lightweight, high-strength TiAlNbB multi-principal element alloy plates with excellent comprehensive performance can be achieved through microstructure control, and fine-grain strengthening is one of the most effective ways to simultaneously improve the material's strength and plasticity. Among the four typical microstructures of TiAlNbB multi-principal element alloys, the dual-phase microstructure (DP) has high strength and room-temperature plasticity due to its fine grains, but its fracture toughness is very low; the equiaxed near-gamma microstructure (NG) has better tensile strength and plasticity than the dual-phase microstructure; the near-lamellar microstructure (NF) and fully lamellar microstructure (FL) have lower tensile strength and plasticity due to the larger lamellar cluster size. The uniform and fine NF or FL microstructure has better plasticity and fracture toughness, resulting in the best overall mechanical properties. However, to obtain the NF or FL microstructure, the TiAlNbB multi-principal element alloy needs to be heated to around 1300℃. Under this high-temperature condition, abnormal grain growth is severe, leading to coarse lamellar cluster size and a significant decrease in room-temperature plasticity. Therefore, obtaining a fine and uniform lamellar microstructure faces a significant challenge. Summary of the Invention

[0005] To overcome the above problems, this invention uses a common metallurgical TiAlNbB multi-principal-element alloy ingot as the billet, and prepares large-size DP microstructure TiAlNbB multi-principal-element alloy plates by hot isostatic pressing and direct cladding hot rolling. Then, a short-time electric pulse heat treatment process is used to prepare large-size TiAlNbB multi-principal-element alloy plates with uniform and fine NF microstructure.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a lightweight, high-strength TiAlNbB multi-principal-element alloy plate, the method comprising:

[0008] S1. Alloy smelting: The composition of the TiAlNbB multi-principal-element alloy plate, according to the atomic percentage of each component, is as follows: Al: 44-49%, Nb: 6-10%, B: 0.1-0.3%, W: 0.01-0.3%, Y: 0.01-0.3%, with the remainder being Ti and unavoidable impurities; the materials are batched according to this atomic percentage, then stirred and smelted, and cast into ingots;

[0009] S2. Hot Isostatic Pressing: The alloy ingot prepared in S1 is subjected to hot isostatic pressing for 4-5 hours under an argon protective atmosphere. The temperature of the hot isostatic pressing is 1230-1250℃ and the pressure is 175MPa. After cooling to 900℃ in the furnace, it is subjected to homogenization annealing for 48 hours and then furnace cooled to room temperature.

[0010] S3. Wire cutting of billet: The alloy ingot prepared in S2 is cut into rectangular billets using an electric discharge wire cutting machine. The dimensions of the billets are 80mm in length, 60mm in width, and 15mm in height.

[0011] S4. Coating treatment: The rectangular blank prepared in S3 is coated with 304 stainless steel or TC4 titanium alloy material. The thickness ratio of the upper and lower cover plates of the coating material to the blank thickness is 1 to 1.3:1, and the width of the frame is 18 to 22 mm. A 1.4 to 1.6 mm thick layer of ZrO powder is filled at the coating interface as a release agent. After vacuuming, the surface is sealed by welding.

[0012] S5. High temperature treatment: Heat the cladding blank prepared in S4 to 1240-1260℃ and keep it at that temperature for 1-2 hours under vacuum or argon protection.

[0013] S6. High-temperature hot rolling treatment: The cladding billet prepared in S5 is subjected to near-isothermal synchronous rolling with one pass and one tempering. The rolling temperature is 1230-1250℃, the rolling speed is 80-100mm / s, and the reduction per pass is controlled at 15-25%. Between each pass, it is held in a vacuum heat treatment furnace at 1230℃ for 15min. After 6 passes of hot rolling, it is furnace cooled to 900℃ and held for 4h, followed by air cooling to room temperature. The deformation during rolling is controlled at 80-90%, and the plate thickness is 2-4mm.

[0014] S7. Electrical pulse heat treatment: After the plate prepared in S6 is taken out of the package, it is subjected to electrical pulse heat treatment. The electrical pulse heating temperature is 1300-1330℃ and the heating time is set to 30-40s. Then it is air-cooled to room temperature to obtain a lightweight and high-strength TiAlNbB multi-principal element alloy plate.

[0015] In one or more embodiments, the smelting method used in S1 is one of plasma cold hearth furnace smelting, vacuum arc smelting, or induction solidification smelting.

[0016] In one or more embodiments, in step S4, the thickness ratio of the upper and lower cover plates of the covering material to the blank thickness is 1.2:1, and the width of the frame is 20mm.

[0017] In one or more embodiments, in step S4, a 1.5 mm thick layer of ZrO powder is filled at the coating interface.

[0018] In one or more embodiments, in step S4, the ZrO stripping agent has a purity of 99.5% and a particle size of 20 μm.

[0019] In one or more embodiments, in step S5, the cladding blank prepared in step S4 is heated to 1250°C and kept at that temperature for 1 hour under vacuum or argon protection.

[0020] In one or more embodiments, in step S6, before the high-temperature hot rolling process, the rolls are preheated to 150-200°C using induction heating or electric heating wire, and the surface of the billet is covered with heat-insulating asbestos cloth during the high-temperature hot rolling process to prevent the plate from cracking due to a significant temperature drop during the hot rolling process.

[0021] In one or more embodiments, in S7, during the electric pulse heat treatment process, a double platinum-rhodium thermocouple wire is used to simultaneously detect the temperature change of the sample surface.

[0022] In one or more embodiments, in S7, the microstructure of the lightweight, high-strength TiAlNbB multi-principal-element alloy plate is a uniform and fine (α2+γ) near-lamellar structure with lamellar cluster size of 13-18 μm; the room temperature yield strength and tensile strength reach 860-935 MPa and 950-998 MPa, respectively, and the room temperature total elongation reaches 3.0-3.8%.

[0023] In a second aspect, the present invention provides a lightweight, high-strength TiAlNbB multi-principal-element alloy plate prepared by the above-described preparation method.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) This invention reduces the temperature of high-temperature hot rolling while increasing the amount of rolling deformation. Using high-temperature hot rolling in the range of 1230 to 1250°C, a DP structure TiAlNbB multi-principal element alloy plate with uniform and fine grain size was prepared. On the one hand, the temperature in this temperature range is relatively low, and the grain size of the plate after large deformation hot rolling will not grow rapidly. On the other hand, hot rolling in this temperature range does not require high equipment performance. Therefore, the prepared plate not only has a high yield but also has a relatively uniform and fine grain size.

[0026] (2) This invention introduces high-energy electric pulse heat treatment technology on the basis of high-temperature hot rolling. High-energy electric pulse is used to heat treat the DP structure alloy plate prepared by hot rolling. Electric pulse heat treatment is rapid and has a short treatment time, avoiding long-term heat preservation in the high-temperature phase region. It not only inhibits the growth of grain size, but also greatly saves energy and time costs.

[0027] (3) The preparation method of the present invention is simple and economical, has low requirements for equipment performance and high yield, and is suitable for large-scale industrial production applications. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0029] Figure 1 The image shows the SEM microstructure of the TiAlNbB multi-principal-element alloy after hot isostatic pressing in Example 1.

[0030] Figure 2 This is a schematic diagram of the TiAlNbB multi-principal-element alloy coating structure in Example 1;

[0031] Figure 3 The microstructure of DP prepared by high-temperature hot rolling in Example 1 is shown in the figure.

[0032] Figure 4 The image shows the (α2+γ) near-lamellae microstructure of the deformed TiAlNbB multi-principal-element alloy plate prepared by electric pulse heat treatment in Example 1.

[0033] Figure 5 The image shows the room temperature tensile mechanical properties of the ultrafine near-lamellar deformed TiAlNbB multi-principal element alloy sheet prepared in Example 1. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0037] Example 1

[0038] Preparation of a lightweight, high-strength TiAlNbB multi-principal-element alloy plate:

[0039] S1. Alloy smelting: The composition of the TiAlNbB multi-principal-element alloy plate is as follows, according to the atomic percentage of each component: Al: 44-49%, Nb: 6-10%, B: 0.1-0.3%, W: 0.01-0.3%, Y: 0.01-0.3%, with the remainder being Ti and unavoidable impurities; the materials are batched according to this atomic percentage and smelted and cast into ingots using a plasma cold hearth furnace.

[0040] S2. Hot Isostatic Pressing (HIP): The ingot prepared by melting in S1 was subjected to HIP to eliminate internal micropores and further homogenize the microstructure. HIP was performed for 4 hours under an argon protective atmosphere at a temperature of 1250℃ and a pressure of 175MPa. After furnace cooling to 900℃, homogenization annealing was carried out for 48 hours, followed by furnace cooling to room temperature. The SEM microstructure of the TiAlNbB multi-principal element alloy after HIP is shown below. Figure 1 As shown.

[0041] S3. Wire cutting of billet: The alloy ingot prepared in S2 is cut into rectangular billets using an electric discharge wire cutting machine. The dimensions of the billets are 80mm × 60mm × 15mm (length × width × height).

[0042] S4. Coating Treatment: The rectangular blank prepared in S3 is coated with TC4 titanium alloy material. The thickness ratio of the upper and lower cover plates of the coating material to the blank thickness is 1.2:1, and the width of the border is 20mm. A 1.5mm thick layer of ZrO powder is filled at the coating interface as a release agent. After vacuuming, the surface is sealed by welding. A schematic diagram of the coating structure is shown below. Figure 2 As shown.

[0043] S5. High-temperature treatment: Heat the cladding blank prepared in S4 to 1250℃ and keep it at that temperature for 1 hour under vacuum or argon protection.

[0044] S6. High-Temperature Hot Rolling Treatment: Before high-temperature hot rolling, the rolls are preheated to 150-200℃ using induction heating or electric heating wire, and the surface of the cladding billet is covered with heat-insulating asbestos cloth during the high-temperature hot rolling treatment. The cladding billet is subjected to near-isothermal synchronous rolling with one pass and one tempering, at a rolling temperature of 1230℃ and a rolling speed of 100mm / s. The reduction per pass is controlled at 15-25%, and the billet is held in a vacuum heat treatment furnace at 1230℃ for 15 minutes between each pass. After 6 passes of hot rolling, the billet is furnace cooled to 900℃ and held for 4 hours, followed by air cooling to room temperature. The deformation during rolling is controlled at 80-90%, and the plate thickness is 2-4mm. The morphology of the DP microstructure prepared by high-temperature hot rolling treatment is as follows: Figure 3 As shown.

[0045] S7. Electrical Pulse Heat Treatment: After removing the prepared plate from the packaging in S6, electrical pulse heat treatment was performed at a temperature of 1300℃ for 40 seconds, followed by air cooling to room temperature to obtain a lightweight, high-strength TiAlNbB multi-principal element alloy plate. The microstructure of the alloy plate is a uniform and fine (α2+γ) near-lamellar structure (see Appendix). Figure 4 The lamellar clusters are approximately 15 μm in size. Its room temperature yield strength and tensile strength reach 935 MPa and 998 MPa, respectively, and its room temperature total elongation reaches 3.2% (see appendix). Figure 5 ).

[0046] Example 2

[0047] Preparation of a lightweight, high-strength TiAlNbB multi-principal-element alloy plate:

[0048] The processes of S1, alloy melting, S2, hot isostatic pressing, S3, billet wire cutting, S4, coating, and S5, high-temperature treatment are the same as in Example 1.

[0049] S6. High-Temperature Hot Rolling Treatment: Before high-temperature hot rolling, the rolls are preheated to 150-200℃ using induction heating or electric heating wire, and the surface of the cladding billet is covered with heat-insulating asbestos cloth during the high-temperature hot rolling treatment. The cladding billet is subjected to near-isothermal synchronous rolling with one pass and one tempering, at a rolling temperature of 1250℃ and a rolling speed of 80mm / s. The reduction per pass is controlled at 15-25%, and the billet is held in a vacuum heat treatment furnace at 1230℃ for 15 minutes between each pass. After 6 passes of hot rolling, the billet is furnace cooled to 900℃ and held for 4 hours, followed by air cooling to room temperature. The deformation during rolling is controlled at 80-90%, and the plate thickness is 2-4mm.

[0050] S7. The electric pulse heat treatment is the same as in Example 1.

[0051] The alloy sheet obtained in this embodiment has a uniform and fine (α2+γ) near-lamellar microstructure, with lamellar clusters approximately 13 μm in size. Its room temperature yield strength and tensile strength reach 930 MPa and 990 MPa, respectively, and its room temperature total elongation reaches 3.8%.

[0052] Example 3

[0053] Preparation of a lightweight, high-strength TiAlNbB multi-principal-element alloy plate:

[0054] S1. The alloy smelting process is the same as in Example 1.

[0055] S2. Hot Isostatic Pressing: The ingot prepared by melting in S1 is subjected to hot isostatic pressing to eliminate micropores inside the ingot and further homogenize the microstructure. Hot isostatic pressing is carried out for 5 hours under an argon protective atmosphere at a temperature of 1230℃ and a pressure of 175MPa. After furnace cooling to 900℃, homogenization annealing is performed for 48 hours, followed by furnace cooling to room temperature.

[0056] The processes of S3, billet wire cutting, S4, coating, S5, high temperature treatment, and S6, high temperature hot rolling are the same as in Example 1.

[0057] S7. Electrical Pulse Heat Treatment: After removing the prepared sheet material from the packaging in S6, electrical pulse heat treatment was performed at a temperature of 1330℃ for 30 seconds, followed by air cooling to room temperature, yielding a lightweight, high-strength TiAlNbB multi-principal element alloy sheet. The microstructure of the alloy sheet was a uniform and fine (α2+γ) near-lamellar structure, with lamellar clusters approximately 18 μm in size. Its room temperature yield strength and tensile strength reached 860 MPa and 950 MPa, respectively, and the total elongation at room temperature reached 4.0%.

[0058] Example 4

[0059] Preparation of a lightweight, high-strength TiAlNbB multi-principal-element alloy plate:

[0060] S1. Alloy Melting: The composition of the TiAlNbB multi-principal-element alloy plate, according to the atomic percentage of each component, is as follows: Al: 44-49%, Nb: 6-10%, B: 0.1-0.3%, W: 0.01-0.3%, Y: 0.01-0.3%, with the remainder being Ti and unavoidable impurities; the materials are batched according to this atomic percentage, and the alloy is cast into ingots using vacuum arc melting or induction solidification melting;

[0061] The processes of S2, hot isostatic pressing, S3, billet wire cutting, S4, cladding, S5, high temperature treatment, S6, high temperature hot rolling, and S7, electric pulse heat treatment are the same as in Example 1.

[0062] This embodiment yields a lightweight, high-strength TiAlNbB multi-principal-element alloy sheet. The microstructure of the alloy sheet is a uniform and fine (α2+γ) near-lamellar structure, with lamellar clusters approximately 17 μm in size. Its room temperature yield strength and tensile strength reach 930 MPa and 970 MPa, respectively, and its room temperature total elongation reaches 3.5%.

[0063] Example 5

[0064] Preparation of a lightweight, high-strength TiAlNbB multi-principal-element alloy plate:

[0065] S1, alloy melting; S2, hot isostatic pressing; S3, billet wire cutting, are the same as in Example 1.

[0066] S4. Coating treatment: The rectangular blank prepared in S3 is coated in the middle of TC4 titanium alloy material. The thickness ratio of the upper and lower cover plates of the coating material to the blank thickness is 1.0:1, and the width of the frame is 20mm. A 1.5mm thick ZrO powder is filled at the coating interface as a release agent. After vacuuming, it is sealed by welding.

[0067] The processes of S5, high-temperature treatment, S6, high-temperature hot rolling treatment, and S7, electric pulse heat treatment are the same as in Example 1.

[0068] This embodiment yields a lightweight, high-strength TiAlNbB multi-principal-element alloy sheet. The microstructure of the alloy sheet is a uniform and fine (α2+γ) near-lamellar structure, with lamellar clusters approximately 19 μm in size. Its room temperature yield strength and tensile strength reach 920 MPa and 980 MPa, respectively, and its room temperature total elongation reaches 3.0%.

Claims

1. A method for preparing a lightweight, high-strength TiAlNbB multi-principal-element alloy plate, characterized in that, The method includes: S1. Alloy smelting: The composition of the TiAlNbB multi-principal-element alloy plate, according to the atomic percentage of each component, is as follows: Al: 44~49%, Nb: 6~10%, B: 0.1~0.3%, W: 0.01~0.3%, Y: 0.01~0.3%, with the remainder being Ti and unavoidable impurities; the materials are batched according to this atomic percentage, then stirred and smelted, and cast into ingots; S2. Hot Isostatic Pressing: The alloy ingot prepared in S1 is subjected to hot isostatic pressing for 4-5 hours under an argon protective atmosphere. The temperature of the hot isostatic pressing is 1230-1250 ℃ and the pressure is 175MPa. After being cooled to 900 ℃ in the furnace, it is subjected to homogenization annealing for 48 hours and then furnace cooled to room temperature. S3. Wire cutting of billet: The alloy ingot prepared in S2 is cut into rectangular billets using an electric discharge wire cutting machine. The dimensions of the billets are 80 mm × 60 mm × 15 mm (length × width × height). S4. Coating treatment: The rectangular blank prepared in S3 is coated with 304 stainless steel or TC4 titanium alloy material. The thickness ratio of the upper and lower cover plates of the coating material to the blank thickness is 1~1.2:1, and the width of the frame is 18~22 mm. A 1.4~1.6 mm thick layer of ZrO powder is filled at the coating interface as a release agent. After vacuuming, it is sealed by welding. S5. High temperature treatment: The coated blank prepared in S4 is heated to 1240~1260 ℃ and held at that temperature for 1 h~2 h under vacuum or argon protection. S6. High-temperature hot rolling treatment: The cladding billet prepared in S5 is subjected to near-isothermal synchronous rolling with one pass and one tempering. The rolling temperature is 1230~1250 ℃, the rolling speed is 80~100 mm / s, the reduction per pass is controlled at 15~25%, and the billet is held in a vacuum heat treatment furnace at 1230 ℃ for 15 min between each pass. After 6 passes of hot rolling, the billet is cooled to 900 ℃ in the furnace and held for 4 h, and then air-cooled to room temperature. The deformation during rolling is controlled at 80~90%, and the plate thickness is 2~4 mm. In S6, before the high-temperature hot rolling treatment, the rolls are preheated to 150~200 ℃ by induction heating or electric heating wire, and the surface of the cladding billet is covered with heat-insulating asbestos cloth during the high-temperature hot rolling treatment. S7. Electrical pulse heat treatment: After the plate prepared in S6 is taken out of the package, it is subjected to electrical pulse heat treatment. The electrical pulse heating temperature is 1300~1330 ℃ and the heating time is set to 30~40 s. Then it is air-cooled to room temperature to obtain a lightweight and high-strength TiAlNbB multi-principal element alloy plate.

2. The preparation method according to claim 1, characterized in that, The smelting method used in S1 is one of plasma cold hearth furnace smelting, vacuum arc smelting, or induction solidification smelting.

3. The preparation method according to claim 1, characterized in that, In S4, the thickness ratio of the upper and lower cover plates of the covering material to the blank thickness is 1.2:1, and the width of the frame is 20 mm.

4. The preparation method according to claim 1, characterized in that, In step S4, a 1.5 mm thick layer of ZrO powder is filled at the coating interface.

5. The preparation method according to claim 1, characterized in that, In step S4, the ZrO stripping agent has a purity of 99.5% and a particle size of 20 μm.

6. The preparation method according to claim 1, characterized in that, In step S5, the cladding blank prepared in step S4 is heated to 1250 °C and kept at that temperature for 1 h under vacuum or argon protection.

7. The preparation method according to claim 1, characterized in that, In S7, during the electric pulse heat treatment process, a double platinum-rhodium thermocouple wire is used to simultaneously detect the temperature change of the sample surface.

8. The preparation method according to claim 1, characterized in that, In the S7, the microstructure of the lightweight and high-strength TiAlNbB multi-principal-element alloy plate is a uniform and fine (α2+γ) near-lamellar structure with lamellar cluster size of 13~18 μm; the room temperature yield strength and tensile strength reach 860~935 MPa and 950~998 MPa, respectively, and the room temperature total elongation reaches 3.0~3.8%.

9. Lightweight, high-strength TiAlNbB multi-principal-element alloy plate prepared by the preparation method according to any one of claims 1 to 8.

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