Preparation method and application of short-process metastable titanium alloy

Abstract

The invention discloses a preparation method and application of a short-process metastable titanium alloy. The plasma technology is utilized, the preparation process of the titanium alloy is optimized, and the product quality and the production efficiency are improved. The method specifically comprises the following steps: firstly, quickly and uniformly melting a titanium alloy raw material in a closed container protected by inert gas through a high-frequency plasma generator, and then atomizing liquid titanium alloy into spherical powder with uniform granularity by utilizing a centrifugal atomization technology; and after screening, the powder is subjected to solution treatment to optimize the organization structure, and finally the high-quality titanium alloy is prepared through a powder metallurgy method. Compared with a traditional titanium alloy preparation method, the method is short in technological process, high in product quality and high in production efficiency. The prepared titanium alloy not only has excellent mechanical property and corrosion resistance, but also meets the requirements of the fields of aviation, aerospace, petroleum, chemical engineering and the like on high-strength and high-corrosion-resistance materials. And good environmental adaptability and operability are achieved, and a new way is provided for industrial production of titanium alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloys, in particular to the preparation of a metastable beta titanium alloy, and specifically is a method for preparing a short-flow metastable titanium alloy by adopting plasma technology. Background Art

[0002] Metal alloys are widely used in aerospace, automobile manufacturing, electronic equipment and other fields. In the preparation of metal alloys, in order to improve the strength and toughness of the materials, methods such as adding alloying elements, heat treatment, and cold working are usually used. For example, the heat resistance and oxidation resistance of the alloy can be improved by adding elements such as molybdenum and chromium; the microstructure of the alloy can be changed by heat treatment, thereby improving its strength and toughness; and the grains of the alloy can be refined by cold working, thereby improving its strength. Although existing metal alloy processing technologies have been able to achieve material strengthening and performance optimization, there are still some problems and challenges. First of all, existing metal alloy preparation technologies have limitations in improving the strength and toughness of materials. In addition, the preparation method is complicated and the process is long, making it difficult to apply on a large scale.

[0003] Titanium and titanium alloys have become important structural materials due to their excellent properties such as low density, high specific strength, excellent fatigue performance, and corrosion resistance. Metastable β titanium alloys are mainly composed of β phase solid solution and a small amount of balanced α phase. They have the highest strengthening effect and have high strength without heat treatment. After quenching and aging, the alloy is further strengthened to meet high-strength application fields. However, traditional metastable titanium alloy preparation methods usually include multiple steps such as smelting, casting, forging, and rolling. These steps are not only time-consuming and labor-intensive, but also difficult to accurately control the composition and organizational structure of the alloy, thus affecting the final performance of the titanium alloy. Summary of the invention

[0004] The present invention provides a short-process metastable titanium alloy and a preparation method thereof. The method utilizes plasma technology, combines centrifugal atomization, powder screening, heat treatment and plate preparation processes, optimizes the preparation process, shortens the process, and improves product quality and production efficiency.

[0005] In order to achieve the above purpose, this technical solution mainly adopts the following technical means: A method for preparing a short-process metastable titanium alloy comprises the following steps: (1) Raw material preparation: Select a titanium alloy raw material that contains at least one β-phase stabilizing element, such as Mo, Zr or Nb, to meet the composition requirements of the metastable titanium alloy; (2) Plasma melting: In a closed container protected by inert gas, a high-frequency plasma generator with an operating frequency between 20 and 50 kHz is used to generate high-temperature plasma to melt the titanium alloy raw material into liquid. The melting temperature is controlled between 1500 and 2500 °C. (3) Centrifugal atomization: The molten titanium alloy liquid is sprayed into a rotating centrifugal chamber through a nozzle at high speed. The speed of the centrifugal chamber is controlled between 1500 and 3000 rpm. The diameter of the nozzle is 0.5 to 2 mm. The liquid titanium alloy is atomized into tiny droplets using centrifugal force to form spherical titanium alloy powder with uniform particle size distribution. The average particle size of the powder is controlled between 30 and 100 μm. (4) Powder screening and collection: The titanium alloy powder obtained by atomization is screened to remove particles with a particle size less than 10 μm or greater than 150 μm, and a more uniform spherical titanium alloy powder with a particle size between 10 μm and 150 μm is obtained; (5) Heat treatment: The spherical titanium alloy powder after screening is subjected to solution treatment at a temperature between 900 and 1100 °C for a holding time of 1 to 4 hours, followed by aging treatment at a temperature between 400 and 600 °C for a holding time of 4 to 8 hours to optimize the microstructure and performance of the alloy; (6) Plate preparation: The heat-treated titanium alloy powder is prepared into a plate by a powder metallurgy method, such as hot pressing sintering or hot isostatic pressing. The sintering temperature is controlled between 1200 and 1800 °C, the pressure is controlled between 30 and 60 MPa, and the insulation time is 1 to 2.5 hours.

[0006] In step (1), the specific composition of the titanium alloy raw material is as follows by mass percentage: Mo is 10% to 20%, Zr is 3% to 8%, Nb is 0-2%, and the balance is Ti, and possible trace alloying elements such as Fe, Al, V, with the total amount not exceeding 5%.

[0007] In step (2), the inert gas is argon and / or helium, and the oxygen content in the sealed container protected by the inert gas is less than 0.05% to ensure that the titanium alloy raw material is not oxidized during the smelting process.

[0008] In step (4), in the powder screening and collection step, a vibrating screen or an air flow classifier is used for screening to ensure the uniformity of the powder particle size.

[0009] In step (6), in the plate preparation step, by adjusting the sintering temperature, pressure and holding time, a titanium alloy plate with a thickness between 1 mm and 5 mm and performance that meets the high strength and high corrosion resistance requirements of aviation, aerospace, petroleum, chemical industry and other fields can be prepared.

[0010] The obtained plate has excellent mechanical properties and corrosion resistance, with a tensile strength of not less than 900 MPa, a yield strength of not less than 800 MPa, and a corrosion rate in 3.5% NaCl solution of less than 0.05 mm / year.

[0011] The beneficial effects of the present invention are:

[0012] (1) Short process flow: The present invention adopts plasma melting and centrifugal atomization technology to directly melt the titanium alloy raw material into liquid and atomize it into powder, eliminating the traditional complex processes such as ingot forging and multi-pass hot rolling, thus significantly shortening the process flow.

[0013] (2) High product quality: The high temperature of plasma can ensure that the raw materials melt quickly and evenly, avoid chemical reactions with the container wall, and improve the purity of the titanium alloy. At the same time, centrifugal atomization technology can produce titanium alloy powder with uniform particle size and high sphericity, providing a basis for the preparation of high-quality plates.

[0014] (3) High production efficiency: The present invention is conducive to the use of automated production equipment, which can achieve continuous production and improve production efficiency. At the same time, due to the short process flow, energy consumption and production costs are reduced.

[0015] (4) Broad application prospects: The prepared short-flow metastable titanium alloy plate has excellent mechanical properties and corrosion resistance, and can be used in application scenarios with high strength and high corrosion resistance requirements in the fields of aviation, aerospace, petroleum, chemical industry, etc. DETAILED DESCRIPTION

[0016] Example 1

[0017] (1) Raw material preparation: A titanium alloy raw material was selected, whose composition was Ti-15Mo-5Zr (mass percentage), which is a typical metastable titanium alloy composition with good strength and corrosion resistance.

[0018] (2) Plasma melting: In a closed container protected by argon, a high-frequency plasma generator with a frequency of 30 kHz is used to melt the titanium alloy raw material into a liquid at a temperature of 2000 °C. During the melting process, the flow rate of argon is controlled at 10L / min to ensure the inertness of the melting environment.

[0019] (3) Centrifugal atomization: The molten titanium alloy liquid is sprayed at high speed through a nozzle with a diameter of 1 mm into a centrifugal chamber with a rotation speed of 2500 rpm, and the liquid titanium alloy is atomized into tiny droplets by centrifugal force. The average particle size of the titanium alloy powder obtained after atomization is 50 μm.

[0020] (4) Powder screening and collection: The titanium alloy powder obtained by atomization is screened using a vibrating screen to remove particles with a particle size less than 20 μm and greater than 80 μm to obtain spherical titanium alloy powder with a more uniform particle size.

[0021] (5) Heat treatment: The sieved spherical titanium alloy powder is solution treated at 1000°C for 2 hours, and then aged at 500°C for 6 hours.

[0022] (6) Plate preparation: The heat-treated titanium alloy powder was prepared into plates by hot pressing sintering method, with the sintering temperature of 1300°C, the pressure of 40 MPa, and the holding time of 1.5 hours. The obtained titanium alloy plate has a thickness of 2 mm, a tensile strength of 950 MPa, a yield strength of 850 MPa, and a corrosion rate of 0.04 mm / year in 3.5% NaCl solution.

[0023] Example 2

[0024] (1) Raw material preparation: A titanium alloy raw material is selected, whose composition is Ti-12Mo-6Zr-2Nb (mass percentage). This is a metastable titanium alloy containing a variety of β-phase stabilizing elements and has higher strength and corrosion resistance.

[0025] (2) Plasma melting: In a closed container protected by helium, a high-frequency plasma generator with a frequency of 40 kHz is used to melt the titanium alloy raw material into a liquid at a temperature of 2200°C. During the melting process, the flow rate of helium is controlled at 15L / min.

[0026] (3) Centrifugal atomization: The molten titanium alloy liquid is sprayed at high speed through a nozzle with a diameter of 1.5 mm into a centrifugal chamber with a rotation speed of 3000 rpm. The average particle size of the titanium alloy powder obtained after atomization is 70 μm.

[0027] (4) Powder screening and collection: The titanium alloy powder obtained by atomization is screened using an air flow classifier to remove particles with a particle size less than 10 μm and greater than 120 μm.

[0028] (5) Heat treatment: The screened spherical titanium alloy powder was solution treated at 1100°C for 3 hours, and then aged at 450°C for 8 hours.

[0029] (6) Plate preparation: The heat-treated titanium alloy powder was prepared into plates by hot isostatic pressing, with a sintering temperature of 1350°C, a pressure of 50 MPa, and a holding time of 2 hours. The obtained titanium alloy plate has a thickness of 3 mm, a tensile strength of 1000 MPa, a yield strength of 900 MPa, and a corrosion rate of 0.03 mm / year in 3.5% NaCl solution.

[0030] Example 3

[0031] (1) Raw material preparation: A titanium alloy raw material was selected, whose composition was Ti-10Mo-8Zr-1Fe (mass percentage). This is a metastable titanium alloy containing trace alloying elements, which aims to improve the mechanical properties and corrosion resistance of the titanium alloy.

[0032] (2) Plasma melting: In a closed container protected by a mixture of argon and helium (volume ratio of 1:1), a high-frequency plasma generator with a frequency of 25 kHz is used to melt the titanium alloy raw material into a liquid at a temperature of 1800°C. During the melting process, the total flow rate of the mixed gas is controlled at 12L / min.

[0033] (3) Centrifugal atomization: The molten titanium alloy liquid is sprayed at high speed through a nozzle with a diameter of 0.8 mm into a centrifugal chamber with a rotation speed of 2000 rpm. The average particle size of the titanium alloy powder obtained after atomization is 40 μm.

[0034] (4) Powder screening and collection: The titanium alloy powder obtained by atomization is screened by combining a vibrating screen and an air flow classifier to remove particles whose particle size does not meet the requirements.

[0035] (5) Heat treatment: The sieved spherical titanium alloy powder was solution treated at 950°C for 4 hours, and then aged at 420°C for 7 hours.

[0036] (6) Plate preparation: The heat-treated titanium alloy powder was prepared into plates by hot pressing sintering method, with the sintering temperature being 1800°C, the pressure being 60 MPa, and the holding time being 2.5 hours. The obtained titanium alloy plate had a thickness of 2.5 mm, a tensile strength of 1600 MPa, a yield strength of 980 MPa, and a corrosion rate of 0.045 mm / year in 3.5% NaCl solution.

[0037] The above embodiments are only used to illustrate the specific implementation of the present invention and do not limit the protection scope of the present invention. In practical applications, the parameters in the embodiments can be adjusted and optimized according to specific needs and conditions.

Claims

1. A method for preparing a short-process metastable titanium alloy, characterized in that: The steps include: (1) Raw material preparation: Select a titanium alloy raw material containing at least one β-phase stabilizing element, Mo, Zr or Nb; (2) Plasma melting: In a closed container protected by inert gas, a high-frequency plasma generator is used to generate high-temperature plasma to melt the titanium alloy raw material into liquid; (3) Centrifugal atomization: The molten titanium alloy liquid is sprayed into a rotating centrifugal chamber at high speed through a nozzle, and the liquid titanium alloy is atomized into tiny droplets by centrifugal force to form spherical titanium alloy powder with uniform particle size distribution. The average particle size of the powder is controlled between 30 and 100 μm. (4) Powder screening and collection: The titanium alloy powder obtained by atomization is screened to remove particles with a particle size less than 10 μm or greater than 150 μm, and a more uniform spherical titanium alloy powder with a particle size between 10 μm and 150 μm is obtained; (5) Heat treatment: The spherical titanium alloy powder after screening is subjected to solution treatment and then aging treatment; (6) Plate preparation: The heat-treated titanium alloy powder is prepared into a plate by a powder metallurgy method. The sintering temperature is controlled between 1200 and 1800°C, the pressure is controlled between 30 and 60 MPa, and the insulation time is 1 to 2.5 hours.

2. The preparation method according to claim 1, characterized in that In step (1), the specific composition of the titanium alloy raw material is as follows by mass percentage: Mo is 10% to 20%, Zr is 3% to 8%, Nb is 0-2%, and the balance is Ti and trace alloying elements, and the total amount of Fe, Al and V does not exceed 5%.

3. The preparation method according to claim 1, characterized in that: In step (2), the inert gas is argon and / or helium, and the oxygen content in the sealed container protected by the inert gas is less than 0.05%.

4. The preparation method according to claim 1, characterized in that: In step (2), the operating frequency of the high-frequency plasma generator is between 20 and 50 kHz; and the smelting temperature is controlled between 1500 and 2500°C.

5. The preparation method according to claim 1, characterized in that: In step (3), the rotation speed of the centrifugal chamber is controlled between 1500 and 3000 rpm, and the diameter of the nozzle is 0.5 to 2 mm.

6. The preparation method according to claim 1, characterized in that: In step (4), in the powder screening and collection step, a vibrating screen or an air flow classifier is used for screening.

7. The preparation method according to claim 1, characterized in that: In step (5), the temperature of the solution treatment is controlled between 900 and 1100° C., and the holding time is 1 to 4 hours; the temperature of the aging treatment is controlled between 400 and 600° C., and the holding time is 4 to 8 hours.

8. The preparation method according to claim 1, characterized in that: In step (6), the thickness of the obtained plate is between 1 mm and 5 mm, and the powder metallurgy method is hot pressing sintering or hot isostatic pressing.

9. A short process metastable titanium alloy, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8, has a tensile strength of not less than 900 MPa, a yield strength of not less than 800 MPa, and a corrosion rate in a 3.5% NaCl solution of less than 0.05 mm / year.