A convenient method for short-process preparation of high-performance titanium alloy components and titanium alloy

Abstract

A convenient method for preparing high-performance titanium alloy components using a short-process process and the titanium alloy itself are disclosed, relating to the field of additive manufacturing of metal materials. The method includes: S1: loading titanium alloy powder into a powder feeder; S2: fixing a substrate on a forming chamber worktable; S3: using a laser as a heat source to melt the titanium alloy powder and deposit it layer by layer onto the substrate; after each layer is deposited, a set time interval is observed before depositing the next layer; S4: after depositing 2-3 layers, the laser powder feeder is removed, and the deposited layers are rolled; S5: repeating steps S3 and S4 to obtain the titanium alloy component. In the laser additive manufacturing process of titanium alloy forming, plastic deformation is introduced, breaking up columnar grains and increasing the distortion energy of the α-phase interface in the thin sheets. Simultaneously, under the subsequent forming thermal cycle, the α-phase in the thin sheets coarsens and spheroidizes to obtain a three-phase microstructure, eliminating the need for subsequent heat treatment and giving the component excellent strength, toughness, and low plasticity anisotropy.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing of metallic materials, and in particular to a convenient method for preparing high-performance titanium alloy components using a short process and the titanium alloy itself. Background Technology

[0002] Titanium alloys possess high specific strength, excellent high-temperature performance, and good corrosion resistance, making them widely used in the manufacture of large and complex aerospace components such as launch vehicle strap-on joints, aircraft panels, and aircraft load-bearing frames. Their usage is a crucial indicator of aircraft performance. Traditional manufacturing methods for large and complex aerospace titanium alloy components employ a "casting + forging + machining + welding" approach, which suffers from long manufacturing cycles, high costs, and low material utilization, hindering the widespread application of titanium alloy components in the aerospace field. Laser additive manufacturing technology, using a laser as a heat source, deposits metal powder layer by layer along a planned path to form dense metal components, followed by minimal machining to obtain high-performance metal components, providing a new solution for the manufacture of large titanium alloy components.

[0003] The three-phase microstructure of titanium alloy consists of primary α phase (α... P ), spheroidized α phase (α G ) and secondary α phase (α S The structure is composed of high-power laser additive manufacturing of titanium alloys with good strength, toughness and high-temperature performance, and good comprehensive performance, making it an ideal structure for engineering applications. The forming power of high-power laser additive manufacturing of titanium alloys is greater than 5.5kW, the layer thickness is generally greater than 1.5mm, the alloy has coarse columnar crystals and intragranular bundle domain structure, and the strength and toughness of the final component are slightly lower than those of forgings. The plasticity of transverse and longitudinal samples is anisotropic. These problems seriously restrict the promotion and application of high-power laser additive manufacturing of titanium alloy components in the aerospace field. Improving the strength and toughness of such components and eliminating plastic anisotropy by adopting appropriate process methods has important engineering application value. At present, researchers mainly use the following two methods to regulate the performance of high-power laser additive manufacturing of titanium alloy components. First, add nucleating particles such as B and Si to the titanium alloy to increase the supercooling of the titanium alloy composition, promote the transformation of columnar grains to equiaxed grains, and obtain fully equiaxed grains and intragranular biphase structure (Precision Forming Engineering, 2019, 11(4): 1-8). Second, during the laser additive manufacturing process, the deposited layer is plastically deformed by ultrasonic impact or layer-by-layer forging, causing recrystallization of the original deposited layer during subsequent forming. After forming, high-temperature solution heat treatment is applied to obtain equiaxed grains and an intragranular dual-phase microstructure (Nature Communions 11, 142 (2020)). The above research provides a new solution for controlling the microstructure of titanium alloy components manufactured using high-power laser additive manufacturing. However, related studies have not yielded a three-phase microstructure of titanium alloys. How to prepare a three-phase microstructure with good overall performance is a challenge facing the engineering application of high-power laser additive manufacturing of titanium alloy components. Summary of the Invention

[0004] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide a convenient method for preparing high-performance titanium alloy components and titanium alloys through a short process. This method can introduce plastic deformation during the laser additive manufacturing of titanium alloys, break columnar grains, and improve the distortion energy of the α phase interface of thin sheets. At the same time, under the action of subsequent forming thermal cycling, the α phase of the thin sheets coarsens and spheroidizes to obtain a three-state structure, without the need for subsequent heat treatment, so that the components have good strength, toughness and low plasticity anisotropy.

[0005] The technical solution provided in this application is as follows:

[0006] A convenient method for fabricating high-performance titanium alloy components using a short-process method includes:

[0007] S1: Load titanium alloy powder into the powder feeder;

[0008] S2: Fix the substrate on the molding chamber worktable;

[0009] S3: When the water and oxygen content in the forming chamber is lower than 50ppm, the titanium alloy powder is melted and deposited onto the substrate layer by layer using a laser as a heat source; after one layer is deposited, the next layer is deposited after a set time interval.

[0010] S4: After continuously depositing 2 to 3 layers, remove the laser powder feeding head and roll the deposited layer;

[0011] S5: Repeat steps S3 and S4 to obtain the titanium alloy component.

[0012] Preferably, in step S3, the laser additive manufacturing parameters during deposition are: laser power 5.5-8.0kW, scanning speed 1600-2000mm / min, spot diameter 6-10mm, overlap rate 55%-65%, powder feeding rate 35-45g / min, and the layer height of the single-layer titanium alloy deposition layer obtained by deposition is 1-2mm.

[0013] Preferably, in step S3, during deposition, the energy density of the titanium alloy deposition layer in the deposition zone is 35–45 J / mm². 2 The overlap ratio is 55%–65% to ensure that the cooling rate of the formed solid-liquid molten pool is 10. 2.8 ~10 3.5 K / s.

[0014] Preferably, in step S3, the deposited layer has a height of 2-3 mm and a dislocation density greater than 10. -22 m -2The titanium alloy sample contains columnar grains with a volume fraction of 100% and a width of 985–1825 μm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.15–1.75 μm.

[0015] Preferably, in step S4, the rolling process parameters are: rolling reduction force of 15-25kN, reduction layer height of 0.5-1.0mm, and rolling speed of 150-350mm / min.

[0016] Rolling breaks down the coarse columnar grains of the original deposited layer, allowing sufficient distortion energy to be stored within the fine micron-sized α-phase. Under subsequent thermal cycling (i.e., the heat generated during each subsequent deposition, i.e., laser additive manufacturing), alloying elements diffuse and migrate within the fine micron-sized α-phase, causing the original α / β interface to become unstable and fracture, forming a new α-phase. Simultaneously, the α-phase coarsens, spheroidizes, and aggregates to form fine α-phase grains. S This allows for the direct acquisition of high-performance titanium alloy components that can be used immediately, reducing the number of manufacturing steps required for large titanium alloy components and lowering manufacturing costs.

[0017] Preferably, in step S3, the time is set to 10-20 minutes.

[0018] Preferably, in step S1, the particle size of the titanium alloy powder is 45–295 μm; the oxygen content of the titanium alloy powder is greater than 0.12 wt%.

[0019] Preferably, in step S1, the [Al] equivalent in the titanium alloy powder is in the range of 2.7 to 6.5.

[0020] Preferably, in step S2, the argon purity content in the forming chamber is not less than 99.99%.

[0021] A high-strength and high-toughness titanium alloy is obtained by any of the above-described methods for the convenient preparation of high-performance titanium alloy components using a short-process approach.

[0022] This invention proposes a convenient short-process method for preparing high-performance titanium alloy components and the titanium alloy itself. The main idea is to control the deposition parameters of the titanium alloy to prepare columnar grains with a layer height of 1-2 mm, a volume fraction of 100%, and a width of 985-1825 μm, and micron-sized flakes with a volume fraction of 100% and a width of 1.15-1.75 μm, with a dislocation density greater than 102. -22 m -2 Titanium alloy samples were obtained; based on this, a rolling device was used to break up the coarse columnar grains, so that the deposited layer obtained long strips of α with a width of no more than 2.67 μm. P Phase, α with a diameter not greater than 6.84 μm GThe phase and volume fraction of α are 47%–58%. S This allows for the direct acquisition of high-performance titanium alloy components that can be used directly.

[0023] In summary, this application includes at least the following beneficial technical effects:

[0024] (1) This invention can directly form high-performance complex titanium alloy components without molds. Compared with the prior art, it can achieve high-performance, short-process and low-cost manufacturing of titanium alloy components without multiple plastic processing and heat treatment.

[0025] (2) The present invention adopts the “forming parameter control + interval rolling” scheme, which can directly produce large and complex titanium alloy components with high strength and toughness without subsequent heat treatment, realize the optimal comprehensive performance of titanium alloy, and provide a new solution for the manufacturing of titanium alloy components. Attached Figure Description

[0026] Figure 1 The TC11 titanium alloy components manufactured by laser additive manufacturing exhibit columnar grains and intragranular dual-phase microstructure; wherein, (a) the macrostructure is characterized by coarse isometric grains, and (b) the microstructure is characterized by fine lamellar microstructure.

[0027] Figure 2 The laser additive manufacturing of TC11 titanium alloy components exhibits equiaxed grains and a special three-state microstructure; wherein, (a) the macrostructure is equiaxed grains, and (b) the microstructure is a three-state microstructure. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely all examples. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] A convenient method for preparing high-performance titanium alloy components using a short process, comprising the following steps:

[0030] The first step is to load titanium alloy powder with a particle size of 45-295μm into the feeding bucket. The oxygen content of the powder must be greater than 0.12wt%.

[0031] The second step is to fix the titanium alloy substrate on the forming chamber worktable filled with argon gas, with the argon gas purity content in the forming chamber not less than 99.99%.

[0032] The third step is to melt the titanium alloy powder and deposit it layer by layer on the substrate when the water and oxygen content in the forming chamber is lower than 50 ppm. After one layer is deposited, the deposition layer is cooled for 10 to 20 minutes before the next layer is deposited.

[0033] In the high-power laser deposition process, the energy density of the titanium alloy deposition layer is controlled to be 35–45 J / mm². 2 The overlap ratio is 35%–45%, resulting in a cooling rate of 10 for the formed solid-liquid molten pool. 2.8 ~10 3.5 K / s, deposition yielded layers with a height of 1–2 mm and a dislocation density greater than 10. -22 m -2 The titanium alloy sample contains columnar grains with a volume fraction of 100% and a width of 985–1825 μm. The columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.15–1.75 μm, which provide sufficient driving force for subsequent macroscopic and microscopic structure control.

[0034] The fourth step is to remove the laser powder feeding head after 2 to 3 layers have been deposited, and then use a rolling device to roll the deposited layer to obtain equiaxed grains with a width of no more than 1865 μm and thin sheet structures with a width of no more than 1.86 μm.

[0035] In the fourth step, the rolling process parameters are as follows: rolling reduction force is 15-25kN, reduction layer height is 0.5-1.0mm, and rolling speed is 150-350mm / min;

[0036] Fifth, repeat steps three and four to continuously process and shape equiaxed grains with a width not exceeding 589 μm and elongated α-grains of 2.67 μm. P Phase, α with a diameter not greater than 6.84 μm G The phase and volume fraction of α are 47%–58%. S This technology enables the high-power laser additive manufacturing of titanium alloy components to meet the application requirements.

[0037] The titanium alloys used in the following examples are all TC11 titanium alloys with an [Al] equivalent of 3.5.

[0038] Example 1

[0039] A convenient method for preparing high-performance titanium alloy components using a short process includes the following steps:

[0040] The first step is to load titanium alloy powder with a particle size of 50μm into the feeding bucket, with an oxygen content of 0.14wt%.

[0041] The second step is to fix the titanium alloy substrate on the forming chamber worktable filled with argon gas, with the argon gas purity content in the forming chamber not less than 99.99%.

[0042] The third step is to melt the titanium alloy powder with a laser as a heat source and deposit it layer by layer on the substrate after the water and oxygen content in the forming chamber is lower than 50 ppm. After one layer is deposited, the deposition layer is cooled for 20 minutes before the next layer is deposited.

[0043] The parameters for laser additive manufacturing during deposition are as follows: laser power 5.5kW, scanning speed 1600mm / min, spot diameter 6mm, overlap ratio 35%, and powder feed rate 35g / min; the resulting monolayer deposition layer has a height of 1mm and a dislocation density of 102. -21.5 m -2 The deposited layer contains columnar grains with a volume fraction of 100% and a width of 1000 μm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.68 μm.

[0044] In the fourth step, after two layers have been deposited consecutively, the laser powder feeding head is removed, and the deposited layer is rolled using a rolling device. The rolling process parameters are as follows: rolling reduction force is 15kN, reduction layer height is 0.5mm, and rolling speed is 150mm / min. At this time, the deposited layer obtains equiaxed grains with a diameter of 1250μm and a lamellar structure with a width of 1.15μm.

[0045] Fifth, repeat steps three and four, continuously processing to obtain equiaxed grains with a width of 550 μm and strips with a width of 2.67 μm and a volume fraction of 35% α. P Phase, 6.8 μm in diameter and α with a volume fraction of 20%. G Phase, 11.8 μm wide and 55% by volume α S This technology enables the high-power laser additive manufacturing of titanium alloy components to meet the application requirements.

[0046] Example 2

[0047] A convenient method for preparing high-performance titanium alloy components using a short process includes the following steps:

[0048] The first step is to load titanium alloy powder with a particle size of 245μm into the powder feeding hopper, with an oxygen content of 0.16wt%.

[0049] The second step is to fix the titanium alloy substrate on the forming chamber worktable filled with argon gas, with the argon gas purity content in the forming chamber not less than 99.99%.

[0050] The third step is to melt the titanium alloy powder with a laser as a heat source and deposit it layer by layer on the substrate after the water and oxygen content in the forming chamber is lower than 50 ppm. After one layer is deposited, the deposition layer is cooled for 10 minutes before the next layer is deposited.

[0051] The parameters for laser additive manufacturing during deposition are as follows: laser power 8.0kW, scanning speed 2000mm / min, spot diameter 10mm, overlap ratio 45%, and powder feed rate 45g / min; the resulting monolayer deposition layer has a height of 2mm and a dislocation density of 102. -21.8 m -2 The deposited layer contains columnar grains with a volume fraction of 100% and a width of 1000 μm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.52 μm.

[0052] The fourth step is to remove the laser powder feeding head after three layers have been deposited, and then use a rolling device to roll the deposited layers. The rolling process parameters are as follows: rolling pressure is 25kN, the lower layer height is 1.0mm, and the rolling speed is 350mm / min.

[0053] Fifth, repeat steps three and four to continuously process and shape equiaxed grains with a width of 520 μm and long strips with a width of 2.36 μm and a volume fraction of 28%. P Phase, 6.24 μm in diameter and α with a volume fraction of 25% G Phase, with a width of 12.5 μm and a volume fraction of 47% α S This technology enables the high-power laser additive manufacturing of titanium alloy components to meet the application requirements.

[0054] Example 3

[0055] A convenient method for preparing high-performance titanium alloy components using a short process includes the following steps:

[0056] The first step is to load titanium alloy powder with a particle size of 200μm into the feeding bucket, with an oxygen content of 0.17wt%.

[0057] The second step is to fix the titanium alloy substrate on the forming chamber worktable filled with argon gas, with the argon gas purity content in the forming chamber not less than 99.99%.

[0058] The third step is to melt the titanium alloy powder with a laser as a heat source and deposit it layer by layer on the substrate after the water and oxygen content in the forming chamber is lower than 50 ppm. After one layer is deposited, the deposition layer is cooled for 15 minutes before the next layer is deposited.

[0059] The parameters for laser additive manufacturing during deposition are as follows: laser power 6.5kW, scanning speed 1800mm / min, spot diameter 8mm, overlap ratio 40%, and powder feed rate 40g / min; the resulting monolayer deposition layer has a height of 1.8mm and a dislocation density of 102. -21.2 m -2The deposited layer contains columnar grains with a volume fraction of 100% and a width of 1000 μm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.38 μm.

[0060] The fourth step is to remove the laser powder feeding head after three layers have been deposited, and then use a rolling device to roll the deposited layers. The rolling process parameters are as follows: rolling pressure is 20kN, the lower layer height is 0.8mm, and the rolling speed is 250mm / min.

[0061] Fifth, repeat steps three and four to continuously process and shape equiaxed grains with a width of 575 μm and long strips with a width of 2.87 μm and a volume fraction of 22%. P Phase, 5.85 μm in diameter and 26% by volume α G Phase, with a width of 11.5 μm and a volume fraction of 52% α S This technology enables the high-power laser additive manufacturing of titanium alloy components to meet the application requirements.

[0062] Example 4

[0063] The only difference from Example 1 is that in the third step, the cooling time interval of the deposited layer is 10 minutes.

[0064] Example 5

[0065] The only difference from Example 1 is that in the third step, the cooling time interval of the deposited layer is 18 minutes.

[0066] Example 6

[0067] The only difference from Example 1 is that in the third step, the parameters for laser additive manufacturing are as follows: laser power 7.2kW, scanning speed 1850mm / min, spot diameter 6mm, overlap rate 62%, and powder feed rate 42g / min; the obtained monolayer deposition layer has a layer height of 1.6mm and a dislocation density of 102. -21 m -2 The deposited layer contains columnar grains with a volume fraction of 100% and a width of 1656 μm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.45 μm.

[0068] Example 7

[0069] The only difference from Example 1 is that in the third step, the laser additive manufacturing parameters are as follows: laser power 6.8kW, scanning speed 1750mm / min, spot diameter 6mm, overlap rate 41%, and powder feed rate 38g / min; the obtained monolayer deposition layer has a layer height of 1.4mm and a dislocation density of 102. -21.4 m -2The deposited layer contains columnar grains with a volume fraction of 100% and a width of 1236 μm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.25 μm.

[0070] Example 8

[0071] The only difference from Example 1 is that in the fourth step, the height of the lower layer is 0.5 mm, and the deposited layer obtains equiaxed grains with a width of 1648 μm and lamellar structures with a width of 1.23 μm.

[0072] Example 9

[0073] The only difference from Example 1 is that in the fourth step, the height of the lower layer is 1.0 mm, and the deposited layer obtains equiaxed grains with a width of 1468 μm and lamellar structures with a width of 1.36 μm.

[0074] Comparative Example

[0075] The only difference from Example 1 is that the comparative titanium alloy sample was obtained by laser additive manufacturing in the third step.

[0076] The microstructure of the comparative sample is Figure 1 The microstructure of the titanium alloy finally obtained in Example 1 was observed, and the following results were obtained. Figure 2 The tensile strength R of the titanium alloys obtained in the above embodiments and comparative examples was measured. m Yield strength R p0.2 The cross-sectional elongation A (%) was tested, and the test results are shown in Table 1.

[0077] Table 1 Comparison of average room temperature tensile properties of laser additively manufactured TC11 titanium alloy components

[0078]

[0079]

[0080] As shown in Table 1, the comparative sample deposited using the conventional high-power deposition method exhibits a fine, lamellar structure, resulting in lower tensile properties than the standard and significant differences in the sectional elongation A between the two directions (indicating plastic anisotropy). Using the method of this invention, the sample exhibits a special three-phase structure, superior tensile properties compared to the standard, and no plastic anisotropy between the two directions.

[0081] As shown in Table 1, when the laser power is too low (less than 5.5kW), the scanning rate is too low (less than 1600mm / min), and the interlayer interval time is too low (less than 10min), the heat input in the laser additive manufacturing process is too low, resulting in a dislocation density of less than 10. -22 m -2The initial sample cannot provide sufficient driving force for subsequent rolling deformation, easily resulting in coarse, thin lamellar structures. This leads to reduced tensile properties and higher plastic anisotropy. When the laser power is too high (greater than 8.0 kW), the scanning rate is too high (greater than 2000 mm / min), and the interlayer interval is too high (greater than 20 min), the heat input in the laser additive forming process is excessive, resulting in a dislocation density below 102. -22 m -2 The specimens tend to have coarse, thin lamellar structures, but exhibit low tensile properties and high plastic anisotropy. Furthermore, excessive heat input can lead to severe thermal stress accumulation during forming, resulting in cracking and rendering the specimens unsuitable for industrial production.

[0082] In step S3, laser additive manufacturing achieves a deposited layer with a dislocation density of less than 10. -22 m -2 At that time, a three-state microstructure could not be obtained through rolling. This application specifies that, under the defined parameters for laser additive manufacturing, the dislocation density of the deposited layer should not exceed 10-1 for obtaining a micron-sized sheet microstructure. -22 m 2 The dislocation density obtained in this application is 10. -22 m -2 ~10 -18 m 2 The deposited layer, after being rolled using the rolling process specified in this application, can produce high-performance short-process titanium alloy components; when the micron-sized flakes obtained in step S3 are less than 1.15 μm, the titanium alloy components are prone to cracking during the rolling process, and titanium alloy components cannot be prepared; when the width of the micron-sized flakes obtained in step S3 is greater than 1.75 μm, high-performance short-process titanium alloy components cannot be obtained.

[0083] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

[0084] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

Claims

1. A short-process method for preparing titanium alloy components, characterized in that, include: S1: Load titanium alloy powder into the powder feeder; S2: Fix the substrate on the molding chamber worktable; S3: When the water and oxygen content in the forming chamber is lower than 50ppm, the titanium alloy powder is melted and deposited onto the substrate layer by layer using a laser as a heat source; after one layer is deposited, the next layer is deposited after a set time interval. The laser additive manufacturing parameters during deposition are: laser power 5.5–8.0 kW, scanning speed 1600–2000 mm / min, spot diameter 6–10 mm, overlap rate 55%–65%, and powder feed rate 35–45 g / min; the layer height of the single-layer titanium alloy deposited layer is 1–2 mm. S4: After continuously depositing 2 to 3 layers, remove the laser powder feeding head and roll the deposited layer; The rolling process parameters are: rolling reduction force 15-25kN, reduction layer height 0.5-1.0mm, and rolling speed 150-350mm / min; S5: Repeat steps S3 and S4 to obtain the titanium alloy component; In step S3, during deposition, the energy density of the titanium alloy deposition layer deposition zone is 35~45 J / mm². 2 The cooling rate of the solid-liquid molten pool is 10. 2.8 ~10 3.5 K / s; In step S3, the titanium alloy sample contains columnar grains with a volume fraction of 100% and a width of 985~1825µm, and the columnar grains contain micron-sized flakes with a volume fraction of 100% and a width of 1.15~1.75µm. In step S4, rolling causes the deposited layer to obtain equiaxed grains with a width of no more than 1865µm and lamellar structures with a width of no more than 1.86µm.

2. The method for preparing a short-process titanium alloy component according to claim 1, characterized in that, In step S3, the time is set to 10-20 minutes.

3. The method for preparing a short-process titanium alloy component according to claim 1, characterized in that, In step S1, the particle size of the titanium alloy powder is 45–295 µm.

4. The method for preparing a short-process titanium alloy component according to claim 1, characterized in that, In step S1, the oxygen content of the titanium alloy powder is greater than 0.12 wt%.

5. The method for preparing a short-process titanium alloy component according to claim 1, characterized in that, In step S1, the [Al] equivalent in the titanium alloy powder is in the range of 2.7 to 6.

5.

6. The method for preparing a short-process titanium alloy component according to claim 1, characterized in that, In step S2, the argon purity content in the forming chamber is not less than 99.99%.

7. A titanium alloy, characterized in that, The titanium alloy component is obtained according to any one of claims 1-6.

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