A short-process preparation method for metastable titanium alloy and its application

Abstract

The present invention discloses a short-process preparation method for metastable titanium alloy and its application. Plasma technology is used to optimize the preparation process of titanium alloys, and improve product quality and production efficiency. Specifically, a high-frequency plasma generator is used to quickly and evenly melt the titanium alloy raw material in a closed container protected by inert gas, and then the liquid titanium alloy is atomized into a spherical powder with uniform particle size using centrifugal atomization technology; after screening, the powder is subjected to solid solution treatment to optimize the organizational structure, and finally a high-quality titanium alloy is made through a powder metallurgy method. Compared with traditional titanium alloy preparation methods, the present invention has a short process flow, high product quality, and high production efficiency. The prepared titanium alloy not only has excellent mechanical and corrosion resistance properties, but also meets the needs of aviation, aerospace, petroleum, chemical and other fields for high-strength, high-corrosion-resistant materials. It also has good environmental adaptability and operability, providing a new way for the industrial production of titanium alloys.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloys, in particular to the preparation of metastable beta titanium alloys, and specifically to a method for preparing short-flow metastable titanium alloys 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 adopted. For example, by adding elements such as molybdenum and chromium, the heat resistance and oxidation resistance of the alloy can be improved; by heat treatment, the microstructure of the alloy can be changed, thereby improving its strength and toughness; by cold working, the grain size of the alloy can be refined, 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 complex and the process is long, making it difficult to apply on a large scale.

[0003] Titanium and its 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 equilibrium 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 the requirements of high-strength applications. However, traditional methods for preparing metastable titanium alloys 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 microstructure 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, combined with centrifugal atomization, powder screening, heat treatment and plate preparation processes, to optimize the preparation process, shorten the process, and improve product quality and production efficiency.

[0005] In order to achieve the above objectives, this technical solution mainly adopts the following technical means:

[0006] A short-process method for preparing a metastable titanium alloy comprises the following steps:

[0007] (1) Raw material preparation: Select titanium alloy raw materials containing at least one β-phase stabilizing element, such as Mo, Zr or Nb, to meet the composition requirements of metastable titanium alloy;

[0008] (2) Plasma melting: In a sealed 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.

[0009] (3) Centrifugal atomization: The molten titanium alloy liquid is sprayed into a rotating centrifugal chamber at high speed through a nozzle. 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 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.

[0010] (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;

[0011] (5) Heat treatment: The spherical titanium alloy powder after screening is subjected to solution treatment. The solution treatment temperature is controlled between 900 and 1100 °C and the holding time is 1 to 4 hours. It is then subjected to aging treatment. The aging treatment temperature is controlled between 400 and 600 °C and the holding time is 4 to 8 hours to optimize the microstructure and performance of the alloy.

[0012] (6) Plate preparation: The heat-treated titanium alloy powder is prepared into plates through powder metallurgy methods, 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 holding time is 1 to 2.5 hours.

[0013] 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, and V, with the total amount not exceeding 5%.

[0014] 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 lower than 0.05% to ensure that the titanium alloy raw material is not oxidized during the smelting process.

[0015] 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.

[0016] 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 and other fields can be prepared.

[0017] 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 of less than 0.05 mm / year in 3.5% NaCl solution.

[0018] The beneficial effects of the present invention are:

[0019] (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.

[0020] (2) High product quality: The high temperature of plasma can ensure that the raw materials are melted quickly and evenly, avoiding chemical reactions with the container wall and improving 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.

[0021] (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.

[0022] (4) Broad application prospects: The prepared short-flow metastable titanium alloy plate has excellent mechanical properties and corrosion resistance, and can be used in applications requiring high strength and high corrosion resistance in the fields of aviation, aerospace, petroleum, and chemical industry. DETAILED DESCRIPTION

[0023] Example 1

[0024] (1) Raw material preparation: Select titanium alloy raw material, whose composition is Ti-15Mo-5Zr (mass percentage), which is a typical metastable titanium alloy composition with good strength and corrosion resistance.

[0025] (2) Plasma melting: In a sealed 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.

[0026] (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 rotating at a speed of 2500 rpm. 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.

[0027] (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.

[0028] (5) Heat treatment: The spherical titanium alloy powder after screening was solution treated at 1000°C for 2 hours, and then aged at 500°C for 6 hours.

[0029] (6) Plate preparation: The heat-treated titanium alloy powder was prepared into plates by hot pressing at a sintering temperature of 1300°C, a pressure of 40 MPa, and a holding time of 1.5 hours. The resulting titanium alloy plate had 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 a 3.5% NaCl solution.

[0030] Example 2

[0031] (1) Raw material preparation: The titanium alloy raw material is selected, and its composition is Ti-12Mo-6Zr-2Nb (mass percentage), which is a metastable titanium alloy containing multiple β-phase stabilizing elements and has higher strength and corrosion resistance.

[0032] (2) Plasma melting: In a sealed 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.

[0033] (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.

[0034] (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.

[0035] (5) Heat treatment: The spherical titanium alloy powder after screening was solution treated at 1100°C for 3 hours, and then aged at 450°C for 8 hours.

[0036] (6) Plate preparation: The heat-treated titanium alloy powder was prepared into plates by hot isostatic pressing (HIP) at a sintering temperature of 1350°C, a pressure of 50 MPa, and a holding time of 2 hours. The resulting titanium alloy plate had 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 a 3.5% NaCl solution.

[0037] Example 3

[0038] (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.

[0039] (2) Plasma melting: In a sealed 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 12 L / min.

[0040] (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.

[0041] (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 with unsatisfactory particle size.

[0042] (5) Heat treatment: The spherical titanium alloy powder after screening was solution treated at 950 °C for 4 hours, and then aged at 420 °C for 7 hours.

[0043] (6) Plate preparation: The heat-treated titanium alloy powder was prepared into plates by hot pressing at a sintering temperature of 1800°C, a pressure of 60 MPa, and a holding time of 2.5 hours. The resulting 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 a 3.5% NaCl solution.

[0044] The above embodiments are only used to illustrate the specific implementation of the present invention and do not limit the scope of protection of the present invention. In actual 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 titanium alloy raw materials, the specific composition of the titanium alloy raw materials is as follows: Mo is 10% to 20%, Zr is 3% to 8%, Nb is 0-2%, and the balance is Ti and trace alloying elements, wherein the total amount of Fe, Al and V in the trace alloying elements does not exceed 5%; (2) Plasma melting: In a sealed container protected by inert gas, a high-frequency plasma generator is used to generate high-temperature plasma to melt the titanium alloy raw materials 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 plates by a powder metallurgy method, wherein the powder metallurgy method is hot pressing sintering or hot isostatic pressing, the sintering temperature is controlled between 1200~1800℃, the pressure is controlled between 30~60MPa, and the holding time is 1~2.5 hours.

2. The preparation method according to claim 1, wherein 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%.

3. The preparation method according to claim 1, wherein In step (2), the operating frequency of the high-frequency plasma generator is between 20 and 50 kHz; and the melting temperature is controlled between 1500 and 2500°C.

4. The preparation method according to claim 1, wherein 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.

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

6. The preparation method according to claim 1, wherein 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.

7. The preparation method according to claim 1, wherein In step (6), the thickness of the obtained plate is between 1 mm and 5 mm.

8. 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 7, 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.