Preparation method of high-temperature / high-strength / high-toughness heterogeneous structure Ti6Al4V alloy

Abstract

The application discloses a preparation method of a high-temperature / high-strength / high-toughness heterogeneous structure Ti6Al4V alloy, which takes a Ti6Al4V alloy forge piece as a matrix, takes Ti6Al4V alloy powder and Ti6.5Al3,5Mo1,5Zr0.3Si alloy powder as deposition materials, controls the alloy powder output by adjusting the rotating speed of a powder feeding barrel, continuously changes the Ti6.5Al3,5Mo1,5Zr0.3Si mass percentage doped into the Ti6Al4V powder in the thickness direction, and prepares a symmetric gradient heterogeneous structure titanium alloy by laser deposition. The application fully utilizes the high specific strength of the Ti6Al4V alloy and the high-temperature characteristics of the Ti6.5Al3,5Mo1,5Zr0.3Si alloy, and the heterogeneous structure Ti6Al4V alloy prepared by the method has excellent tensile strength and impact toughness. The application is suitable for the preparation process of the 3D printing heterogeneous structure Ti6Al4V alloy which is easy to realize.

Description

Technical Field

[0001] This invention relates to a method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy, belonging to the field of alloy materials technology. Background Technology

[0002] Ti6Al4V alloy is the most widely used medium-strength titanium alloy. It has relatively stable microstructure and properties, and possesses high specific strength, high yield strength ratio, and good corrosion resistance. In the aerospace field, it is mainly used to manufacture engine fans and compressor discs and blades, as well as important load-bearing components such as beams, joints, and bulkheads in aircraft structures. With the rapid development of aerospace technology, high-energy equipment places increasingly higher demands on the performance of titanium alloys, especially the need for high temperature, high strength, and high toughness. However, high-temperature titanium alloys, high-strength titanium alloys, and high-toughness titanium alloys have limited properties and can only be used within specific temperature and stress ranges. They cannot simultaneously meet the performance requirements of high temperature, high strength, and high toughness, and cannot achieve the service goals of high temperature gradients and high stress gradients in different parts of key components. Therefore, some scholars have proposed controlling the microstructures of various characteristic sizes to generate strain gradients between heterogeneous structures under stress, thereby breaking through the traditional inverse relationship of "strength-toughness" in materials and enabling heterogeneous structures to obtain excellent comprehensive mechanical properties.

[0003] Controllable fabrication of heterostructured titanium alloys is key to optimizing heterostructures. Laser deposition, with its layer-by-layer deposition characteristics, enables controllable fabrication of microstructures. Furthermore, this method is efficient and simple, making it a crucial approach for preparing heterostructured metallic materials. Since Ti6.5Al3.5Mo1.5Zr0.3Si alloy is a high-temperature titanium alloy developed in my country, controlling and fully utilizing the high strength and high toughness of Ti6Al4V alloy, as well as the high-temperature properties of Ti6.5Al3.5Mo1.5Zr0.3Si alloy, to obtain a high-temperature / high-strength / high-toughness titanium alloy is of paramount importance.

[0004] CN108941552B discloses a Ti / Ti6Al4V composite material with continuously gradient composition prepared by 3D printing technology. The substrate is Ti, and the powder is Ti6Al4V. However, the first layer is formed by cladding the substrate with a laser beam or electron beam, followed by feeding Ti6Al4V powder onto the cladding position, creating the first cladding layer. The second layer is formed by scanning the first cladding layer with a laser beam, followed by feeding Ti6Al4V powder onto the same laser-scanned position, creating the second gradient layer, and so on. This gradient material prepared by 3D printing uses only one type of Ti6Al4V powder, but the laser beam cladding first causes a high dilution effect, changing the Al and V content and thus altering the sample composition. However, firing the laser first is equivalent to dry-burning the substrate or the next cladding layer, which easily leads to cracks, increased dilution, and decreased performance. Normally, the powder is fired first, followed by the laser. Summary of the Invention

[0005] The purpose of this invention is to improve the performance of Ti6Al4V alloy by providing a method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy, and an easily implementable 3D printing process for preparing the heterostructure Ti6Al4V alloy.

[0006] The technical solution of the present invention is as follows: a method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy. The method uses a Ti6Al4V alloy forging as the substrate and Ti6.5Al3, 5Mo1, and 5Zr0.3Si alloy powder as deposition materials. The amount of alloy powder output is controlled by adjusting the rotation speed of the powder feeding barrel. The mass percentage of Ti6.5Al3, 5Mo1, and 5Zr0.3Si is continuously changed in the thickness direction and doped into the Ti6Al4V powder. A symmetrical gradient heterostructure titanium alloy is prepared by laser deposition.

[0007] A method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy, the specific steps of which are as follows:

[0008] (1) Material selection: Ti6Al4V alloy forgings are used as the substrate, and their surfaces are ground and cleaned; Ti6Al4V alloy powder and Ti6.5Al3, 5Mo1, and 5Zr0.3Si alloy powders are selected as deposition materials; the particle size of the Ti6Al4V alloy powder and Ti6.5Al3, 5Mo1, and 5Zr0.3Si alloy powders is 100~400 μm.

[0009] (2) Place the Ti6Al4V alloy forging in an argon-protected chamber.

[0010] (3) The Ti6Al4V alloy powder and Ti6.5Al3, 5Mo1 and 5Zr0.3Si alloy powder are fed to the Ti6Al4V alloy forging via a dual-path coaxial feeder.

[0011] (4) The powder output is controlled by adjusting the rotation speed of the powder feeding hopper; the mass percentages of Ti6.5Al3, 5Mo1, and 5Zr0.3Si are continuously changed in the thickness direction, and a heterostructure Ti6Al4V alloy is prepared by laser deposition technology;

[0012] (5) The obtained heterostructure Ti6Al4V alloy is placed in a heat treatment furnace for heat treatment.

[0013] The Ti6Al4V alloy forgings were ultrasonically cleaned with acetone and anhydrous ethanol after grinding.

[0014] The Ti6Al4V alloy forgings were prepared in an argon-protected chamber using a high-precision dual-path coaxial powder feeding system via laser deposition to create heterogeneous Ti6Al4V alloy forgings.

[0015] The particle size of the Ti6Al4V alloy powder and the Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy powder is 100~200 μm.

[0016] The powder output is controlled by adjusting the rotation speed of the powder feeding hopper. The mass percentages of Ti6.5Al3, 5Mo1, and 5Zr0.3Si are continuously changed along the thickness direction to 20wt.%, 40wt.%, 60wt.%, 80wt.%, 60%, 40%, and 20% of the total weight, respectively, with each deposition thickness being 4~6mm.

[0017] The laser deposition technology has the following specific process parameters: laser power of 6.6~7.0kW, scanning rate of 1000~1200mm / min, spot diameter of 7.3-7.6mm, scanning spacing of 3~5mm, powder feed rate of 1200~1300g / h, layer thickness of 0.8~1.0mm, powder feed gas flow rate of 13.5~14.0L / min, and coaxial optical path gas pressure of 0.4~0.6MPa.

[0018] The Ti6Al4V alloy heterostructure is subjected to a double annealing process. First, the titanium alloy component is placed in a heat treatment furnace at a temperature of 940~980℃ and held for 4~6 hours before being air-cooled to room temperature. Then, it is placed in a heat treatment furnace at a temperature of 580~620℃ and held for 4~6 hours before being air-cooled to room temperature.

[0019] The heterostructured Ti6Al4V alloy component has a strength greater than 1000 MPa and an impact toughness greater than 60 J / cm. 2 .

[0020] The beneficial effects of this invention are that it fully utilizes the high specific strength of Ti6Al4V alloy and the high-temperature characteristics of Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy to prepare heterostructured Ti6Al4V alloys. By designing a mixture of the two materials, the advantages of both are leveraged, resulting in an alloy with excellent tensile strength and impact toughness. This invention is simple to operate, and the selected process parameters have very low requirements for equipment and environment, closely aligning with practical engineering applications. This invention is applicable to easily implemented 3D printing processes for preparing heterostructured Ti6Al4V alloys. Attached Figure Description

[0021] Figure 1 SEM image of Ti6Al4V alloy powder;

[0022] Figure 2 SEM images of Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy powders;

[0023] Figure 3 These are grain boundaries of the Ti6Al4V alloy;

[0024] Figure 4 These are grain boundaries of the Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy;

[0025] Figure 5 The tensile results of the heterostructure Ti6Al4V alloy of this invention are shown.

[0026] Figure 6 The impact results of the heterostructure Ti6Al4V alloy of this invention;

[0027] Figure 7 This invention provides a preparation process for a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy. Detailed Implementation

[0028] Specific embodiments of the present invention are as follows: Figure 7 The process is shown below.

[0029] This embodiment describes a method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy, with the following specific steps:

[0030] (1) Material selection

[0031] Ti6Al4V alloy forgings were selected as the base material. After grinding, the surface was cleaned by ultrasonic cleaning with acetone and anhydrous ethanol.

[0032] Ti6Al4V alloy powder and Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy powder were selected as deposition materials; the particle size of Ti6Al4V alloy powder and Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy powder was 100~400um.

[0033] (2) Place the cleaned Ti6Al4V alloy forging in an argon-protected chamber.

[0034] (3) Ti6Al4V alloy powder and Ti6.5Al3, 5Mo1, and 5Zr0.3Si alloy powder are synchronously fed to the Ti6Al4V alloy forging in the argon protection chamber through a high-precision dual-path coaxial powder feeding system. The high-precision dual-path coaxial powder feeding system is connected to two powder feeders. The two types of powder are placed into the two powder feeders respectively. The powder feeding amount is controlled by adjusting the rotation speed of the powder feeders. The powder fed into the two powder feeders is combined into one powder tube and sent out, which is similar to a Y-shaped powder feeding tube, thereby achieving the requirements of different mass percentages of mixed powder.

[0035] Powder feeding rate 1200~1300g / h, layer thickness 0.8~1.0mm, powder feeding air flow rate 13.5~14.0L / min, coaxial optical path air pressure 0.4~0.6MPa.

[0036] (4) The powder output is controlled by adjusting the rotation speed of the powder feeding tank, and the mass percentage of Ti6.5Al3, 5Mo1, and 5Zr0.3Si is continuously changed in the thickness direction, with a deposition thickness of 4~6mm each time:

[0037] The first two layers consist of 80% Ti6Al4V and 20% Ti6.5Al3.5Mo1.5Zr0.3Si; the third and fourth layers consist of 60% Ti6Al4V and 40% Ti6.5Al3.5Mo1.5Zr0.3Si; the fifth and sixth layers consist of 40% Ti6Al4V and 60% Ti6.5Al3.5Mo1.5Zr0.3Si; the seventh and eighth layers consist of 20% Ti6Al4V and 80% Ti6.5Al3.5Mo1.5Zr0.3Si. Layers 9-10: 40% Ti6Al4V + 60% Ti6.5Al3.5Mo1.5Zr0.3Si; Layers 11-12: 60% Ti6Al4V + 40% Ti6.5Al3.5Mo1.5Zr0.3Si; Layers 13-14: 80% Ti6Al4V + 20% Ti6.5Al3.5Mo1.5Zr0.3Si.

[0038] In an argon-protected chamber, a heterostructured Ti6Al4V alloy was prepared by laser melting of alloy powder deposited onto a substrate.

[0039] In laser deposition, the laser power is 6.6~7.0kW, the scanning rate is 1000~1200mm / min, the spot diameter is 7.3-7.6mm, and the scanning spacing is 3~5mm.

[0040] (5) The obtained heterostructure Ti6Al4V alloy is placed in a heat treatment furnace for heat treatment. The Ti6Al4V alloy heterostructure is subjected to a double annealing process; first, the titanium alloy component is placed in a heat treatment furnace at a temperature of 940~980℃, held for 4~6h and then air-cooled to room temperature; then it is placed in a heat treatment furnace at a temperature of 580~620℃, held for 4~6h and then air-cooled to room temperature.

[0041] Figure 1 and Figure 2 The characteristics of the Ti6Al4V alloy powder and the Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy powder selected in the embodiments of the present invention are shown respectively. As can be seen from the figure, the powders all exhibit good sphericity, with no satellite powders present, and the particle size is approximately 100~200 μm.

[0042] Figure 3 and Figure 4 The grain boundary results for Ti6Al4V alloy and Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy are shown respectively. It was found that the α-structure of Ti6Al4V alloy is relatively coarse, while the acicular α-structure of Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy is relatively fine. Without changing the α-structure, the content of Ti6.5Al3, 5Mo1, 5Zr0.3Si alloy gradually changes along the thickness direction, and the content of acicular α-lamellae gradually changes, thus maximizing the macroscopic non-uniformity of the gradient structure.

[0043] Figure 5 and Figure 6 The tensile and impact results are shown respectively. It is found that the tensile strength and impact performance of the heterostructure Ti6Al4V alloy after two heat treatments are higher than those of Ti6Al4V alloy and Ti6.5Al3, 5Mo1, 5Zr0.3Si, which shows that the gradient structure has an additional effect on the mechanical properties. Therefore, the heterostructure titanium alloy has better comprehensive strength and toughness than the homogeneous material.

Claims

1. A method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy, characterized in that, The method uses Ti6Al4V alloy forgings as the substrate, grinding and cleaning their surfaces; Ti6Al4V alloy powder with a particle size of 100~400um and Ti6.5Al3.5Mo1.5Zr0.3Si alloy powder as deposition materials, controlling the amount of alloy powder output by adjusting the rotation speed of the powder feeder, and continuously changing the mass percentage of Ti6.5Al3.5Mo1.5Zr0.3Si in the thickness direction to 20wt.%, 40wt.%, 60wt.%, 80wt.%, 60wt.%, 40wt.%, and 20wt.% of the total weight, with a deposition thickness of 4~6mm each time, doping into Ti6Al4V powder, and preparing a symmetrical gradient heterostructure titanium alloy by laser deposition; In an argon-protected chamber, Ti6Al4V alloy forgings are prepared by feeding Ti6Al4V alloy powder and Ti6.5Al3.5Mo1.5Zr0.3Si alloy powder onto the Ti6Al4V alloy forgings using a high-precision dual-path coaxial powder feeding system. The resulting heterogeneous Ti6Al4V alloy is then deposited via laser deposition. The high-precision dual-path coaxial powder feeding system has two powder feeders, into which the two powders are placed. The powder feeding rate is controlled by adjusting the rotation speed of the powder feeders, and a Y-shaped powder feeding tube is used to combine the powder from the two feeders into a single tube for output. The obtained heterostructured Ti6Al4V alloy was placed in a heat treatment furnace for heat treatment to obtain a high-temperature, high-strength, and high-toughness heterostructured Ti6Al4V alloy. The heterostructured Ti6Al4V alloy is subjected to a double annealing process: first, the titanium alloy component is placed in a heat treatment furnace at a temperature of 940~980℃, held for 4~6 hours, and then air-cooled to room temperature; then, it is placed in a heat treatment furnace at a temperature of 580~620℃, held for 4~6 hours, and then air-cooled to room temperature. The heterostructured Ti6Al4V alloy component has a strength greater than 1000 MPa and an impact toughness greater than 60 J / cm. 2 ; The laser deposition process parameters are as follows: laser power of 6.6~7.0kW, scanning rate of 1000~1200mm / min, spot diameter of 7.3-7.6mm, scanning spacing of 3~5mm, powder feed rate of 1200~1300g / h, layer thickness of 0.8~1.0mm, powder feed gas flow rate of 13.5~14.0L / min, and coaxial optical path gas pressure of 0.4~0.6MPa.

2. The method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy according to claim 1, characterized in that, The Ti6Al4V alloy forgings were ultrasonically cleaned with acetone and anhydrous ethanol after grinding.

3. The method for preparing a high-temperature / high-strength / high-toughness heterostructure Ti6Al4V alloy according to claim 1, characterized in that, The particle size of the Ti6Al4V alloy powder and the Ti6.5Al3.5Mo1.5Zr0.3Si alloy powder is 100~200um.

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