A high temperature resistant titanium alloy and its preparation method and application

Abstract

The present invention belongs to the technical field of titanium alloys, and specifically relates to a high-temperature resistant titanium alloy, a preparation method thereof and an application thereof. The high-temperature resistant titanium alloy provided by the present invention comprises the following elemental components in percentage by mass: 6% Al, 4.8% Nb, 0.5% Si and the remainder Ti. The present invention adds 0.5% Si to the titanium alloy to improve the high-temperature performance and creep resistance of the alloy; Nb, as a β-stabilizing element of the Ti alloy, can increase the content of β phase in the alloy, thereby improving the plasticity of the alloy; the Nb element can also increase the solubility and solid solution stability of Si. The present invention improves the high-temperature resistance of the titanium alloy by limiting the mass percentages of silicon and niobium to 0.5% and 4.8%, so that the titanium alloy can maintain good mechanical properties after long-term service in a high-temperature (600°C) environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloys, and in particular relates to a high temperature resistant titanium alloy and a preparation method and application thereof. Background Art

[0002] Titanium alloys have excellent properties such as high specific strength, good corrosion resistance and biocompatibility, and are widely used in aerospace, deep-sea mining, medical equipment and other fields. With the advancement of science and technology, the application environment of titanium alloys is becoming more and more complex. Especially with the rapid development of the new generation of aerospace vehicles, the service environment of key titanium alloy structural parts is becoming more severe (high temperature), so the performance requirements of titanium alloys are also getting higher and higher, especially the mechanical properties at high temperatures. However, the existing Ti-Al-Nb-Si alloy has excellent yield strength, tensile strength and elongation at room temperature, but its yield strength, tensile strength and elongation in high temperature (600℃) environment are poor. Summary of the invention

[0003] In view of this, the present invention provides a high-temperature resistant titanium alloy and a preparation method and application thereof. The high-temperature resistant titanium alloy provided by the present invention still has high yield strength, tensile strength and elongation in a high-temperature environment of 600°C.

[0004] In order to solve the above technical problems, the present invention provides a high temperature resistant titanium alloy, comprising the following element components in percentage by mass:

[0005]

[0006] The present invention also provides a method for preparing the high temperature resistant titanium alloy described in the above technical solution, comprising the following steps:

[0007] Mixing titanium powder, niobium powder, aluminum powder and silicon powder to obtain a mixed material;

[0008] The mixed material is 3D printed to obtain the high temperature resistant titanium alloy.

[0009] Preferably, the average particle size of the titanium powder, niobium powder, aluminum powder and silicon powder is independently 15 to 53 μm.

[0010] Preferably, the mixing is carried out under the condition of mechanical stirring, the rotation speed of the mechanical stirring is 60 to 90 r / min, and the time of the mechanical stirring is 1.5 to 2.5 h.

[0011] Preferably, after the mixing, the further step includes: drying the mixed system to obtain a mixed material; the drying temperature is 90 to 110° C., and the drying time is 1.8 to 2.2 hours.

[0012] Preferably, the 3D printing includes laser selective melting printing.

[0013] Preferably, when the equipment used for laser selective melting printing is BLT-S210, the printing parameters are as follows: laser power 155w, scanning speed 1200mm / s, layer thickness 0.03mm, scanning spacing 0.1mm, scanning rotation increment 67°

[0014] The present invention also provides applications of the high temperature resistant titanium alloy described in the above technical solution or the high temperature resistant titanium alloy prepared by the preparation method described in the above technical solution in the fields of aviation, aerospace and deep sea exploration.

[0015] The present invention provides a high temperature resistant titanium alloy, comprising the following element components in percentage by mass: 6% Al, 4.8% Nb, 0.5% Si and the balance Ti. In the present invention, Al is used as an α-stabilizing metal element of the Ti alloy to play a role in solid solution strengthening and improve the specific strength of the Ti alloy. In order to prevent α 2 (Ti 3 Al) phase is formed, which causes the brittleness of the material. The present invention limits the mass content of Al in the titanium alloy to 6wt%. At the same time, adding 0.5% Si to the titanium alloy improves the high temperature performance and creep resistance of the alloy; Nb, as a β-stabilizing element of the Ti alloy, can increase the content of β phase in the alloy, thereby improving the plasticity of the alloy; the Nb element can also increase the solubility and solid solution stability of Si. The present invention improves the high temperature resistance of the titanium alloy by limiting the mass percentage of silicon and niobium to 0.5% and 4.8%, so that the titanium alloy can maintain good mechanical properties in long-term service in a high temperature (600°C) environment. It can be seen from the test results of the embodiment that the high temperature resistant titanium alloy provided by the present invention has a yield strength of 782MPa, a tensile strength of 840MPa, and an elongation of 16% at high temperature (600°C). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is the stress-strain curve of the titanium alloy of Example 1 and Comparative Examples 1 and 2 at room temperature;

[0017] Figure 2 This is a metallographic diagram of the high temperature resistant titanium alloy prepared in Example 1;

[0018] Figure 3 This is the SEM image of the high temperature resistant titanium alloy prepared in Example 1. DETAILED DESCRIPTION

[0019] The present invention provides a high temperature resistant titanium alloy, comprising the following element components in percentage by mass:

[0020]

[0021]

[0022] The present invention also provides a method for preparing the high temperature resistant titanium alloy described in the above technical solution, comprising the following steps:

[0023] Mixing titanium powder, niobium powder, aluminum powder and silicon powder to obtain a mixed material;

[0024] The mixed material is 3D printed to obtain the high temperature resistant titanium alloy.

[0025] The present invention mixes titanium powder, niobium powder, aluminum powder and silicon powder to obtain a mixed material. In the present invention, the titanium powder is preferably spherical; the average particle size of the titanium powder is preferably 15 to 53 μm, more preferably 20 to 40 μm. In the present invention, the niobium powder is preferably spherical; the average particle size of the niobium powder is preferably 15 to 53 μm, more preferably 20 to 45 μm. In the present invention, the aluminum powder is preferably spherical; the average particle size of the aluminum powder is preferably 15 to 53 μm, more preferably 25 to 50 μm. In the present invention, the silicon powder is preferably spherical; the average particle size of the silicon powder is preferably 15 to 53 μm, more preferably 23 to 48 μm.

[0026] In the present invention, the mixing is preferably carried out under the condition of mechanical stirring; the rotation speed of the mechanical stirring is preferably 60 to 90 r / min, more preferably 70 to 80 r / min; the time of the mechanical stirring is preferably 1.5 to 2.5 h, more preferably 2 h.

[0027] In the present invention, after the mixing, it is preferred that the mixed system is dried to obtain a mixed material. In the present invention, the drying temperature is preferably 90 to 110°C, more preferably 100°C; the drying time is preferably 1.8 to 2.2 hours, more preferably 2 hours. In the present invention, the drying is preferably carried out in a vacuum dryer. The present invention can improve the fluidity of the mixed material through drying, which is beneficial to the subsequent 3D printing.

[0028] After obtaining the mixed material, the present invention performs 3D printing on the mixed material to obtain the high temperature resistant titanium alloy. In the present invention, the 3D printing preferably includes laser selective melting printing (SLM). The present invention has no special requirements for the process conditions of the laser selective melting printing, as long as the density of the high temperature resistant titanium alloy can reach more than 99.9%. In an embodiment of the present invention, when the equipment used for the laser selective melting printing is BLT-S210, the printing parameters are as follows: laser power 155w, scanning speed 1200mm / s, layer thickness 0.03mm, scanning spacing 0.1mm, scanning rotation increment 67°.

[0029] The present invention preferably obtains the corresponding titanium alloy component by one-step molding according to the structural dimensions required by the titanium alloy.

[0030] The present invention adopts 3D printing to prepare titanium alloy, which can avoid the macro-segregation of elements that occurs in traditional casting methods and is conducive to the homogenization of alloy components. Because 3D printing uses a layer-by-layer stacking method to manufacture products, it can produce beautifully structured and complex formed parts; the utilization rate of raw materials for 3D printing can be close to 100% (excluding supports), avoiding waste of materials and energy, and saving costs; and 3D printing is an integrated printing assembly, which effectively avoids the assembly error between samples that leads to poor performance of the assembly.

[0031] The present invention adopts the SLM additive manufacturing technology to prepare titanium alloy materials by in-situ alloying method, which has the following advantages: (1) SLM technology can adjust the alloy composition ratio within a large range by controlling the amount of powder mixing, and quickly realize the alloy composition design; (2) The energy density of the laser heat source output adopted by SLM technology is large, which can quickly melt the refractory metal powder and quickly solidify it in a short time, greatly reducing the macro segregation of alloy elements and making the alloy composition more uniform.

[0032] The present invention also provides applications of the high temperature resistant titanium alloy described in the above technical solution or the high temperature resistant titanium alloy prepared by the preparation method described in the above technical solution in the fields of aviation, aerospace and deep sea exploration.

[0033] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0034] Example 1

[0035] Spherical titanium powder with an average particle size of 20 μm, spherical niobium powder with an average particle size of 20 μm, spherical aluminum powder with an average particle size of 25 μm and spherical silicon powder with an average particle size of 23 μm are mechanically stirred at a rotation speed of 80 r / min for 2 hours and then placed in a vacuum dryer for drying at 100° C. for 2 hours to obtain a mixed material; the mass percentage of aluminum in the mixed material is 6%, the mass percentage of niobium is 4.8%, and the mass percentage of silicon is 0.5%.

[0036] The mixed material was used as raw material for laser selective melting printing using BLT-S210 equipment to obtain titanium alloy; the printing parameters of the BLT-S210 equipment were: laser power 155w, scanning speed 1200mm / s, layer thickness 0.03mm, scanning spacing 0.1mm, and scanning rotation increment 67°.

[0037] Comparative Example 1

[0038] A titanium alloy is prepared according to the method of Example 1, except that the mass percentage of aluminum in the mixed material is 6%, the mass percentage of silicon is 0.4%, and the mass percentage of niobium is 8.8%.

[0039] Comparative Example 2

[0040] A titanium alloy is prepared according to the method of Example 1, except that the mass percentage of aluminum in the mixed material is 6%, the mass percentage of silicon is 0.3%, and the mass percentage of niobium is 12%.

[0041] The mechanical properties of the titanium alloys in Example 1 and Comparative Examples 1 to 2 were tested at 600°C according to GB / T228.1-2010, and the stress-strain curves were as follows: Figure 1 The yield strength, tensile strength and elongation at break calculated from the stress-strain curve are listed in Table 1.

[0042] Table 1 Mechanical properties of titanium alloys in Example 1 and Comparative Examples 1-2

[0043] Example Yield strength (MPa) Tensile strength(MPa) Elongation at break (%) Example 1 782 840 16 Comparative Example 1 747 783 4 Comparative Example 2 663 731 12.5

[0044] Combining Table 1 and Figure 1 It can be seen that the Ti-6Al-4.8Nb-0.5Si alloy provided in the embodiment of the present invention still has excellent yield strength, tensile strength and elongation at high temperature compared with the alloys of Comparative Examples 1 and 2. The titanium alloy provided by the present invention has good high-temperature mechanical properties. On the one hand, it can be attributed to the addition of Si elements. Reasonable addition of Si elements can improve the high-temperature performance and creep resistance of titanium alloys; on the other hand, it is attributed to the appropriate addition of Nb elements. Nb elements can improve the solubility and solid solution stability of Si. At the same time, Nb is a β-stabilizing element of titanium alloys. The appropriate addition of Nb elements can make the titanium alloy form a two-phase structure, improve the plasticity of the alloy, and under the joint action of specific contents of silicon and niobium, the titanium alloy still has excellent yield strength, tensile strength and elongation at high temperature.

[0045] The high temperature resistant titanium alloy prepared in Example 1 was corroded with Koll reagent for 2 minutes and then the corroded sample was observed using a metallographic microscope to obtain a metallographic image, as shown in FIG. Figure 2 The high temperature resistant titanium alloy prepared in Example 1 was observed by scanning electron microscope to obtain a SEM image, as shown in FIG. Figure 3 As shown. Figure 2 and Figure 3 It can be seen that no observable pore defects are found in the high temperature resistant titanium alloy structure prepared in Example 1, which provides a basis for improving high temperature resistance.

[0046] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A high temperature resistant titanium alloy, characterized in that: Includes the following elemental components in mass percentage: Al 6%； Nb 4.8%; Si 0.5%; Ti remainder; The preparation method of the high temperature resistant titanium alloy comprises the following steps: Mixing titanium powder, niobium powder, aluminum powder and silicon powder to obtain a mixed material; Performing 3D printing on the mixed material to obtain the high temperature resistant titanium alloy; The high temperature resistant titanium alloy has a yield strength of 782 MPa at 600° C., a tensile strength of 840 MPa, and an elongation of 16%.

2. The method for preparing the high temperature resistant titanium alloy according to claim 1, comprising the following steps: Mixing titanium powder, niobium powder, aluminum powder and silicon powder to obtain a mixed material; The mixed material is 3D printed to obtain the high temperature resistant titanium alloy.

3. The preparation method according to claim 2, characterized in that: The average particle sizes of the titanium powder, niobium powder, aluminum powder and silicon powder are independently 15-53 μm.

4. The preparation method according to claim 2 or 3, characterized in that: The mixing is carried out under the condition of mechanical stirring, the rotation speed of the mechanical stirring is 60-90 r / min, and the time of the mechanical stirring is 1.5-2.5 h.

5. The preparation method according to claim 4, characterized in that: After the mixing, the method further comprises: drying the mixed system to obtain a mixed material; the drying temperature is 90-110° C. and the drying time is 1.8-2.2 hours.

6. The preparation method according to claim 2, characterized in that: The 3D printing includes laser selective melting printing.

7. The preparation method according to claim 6, characterized in that: When the equipment used for laser selective melting printing is BLT-S210, the printing parameters are as follows: laser power 155W, scanning speed 1200mm / s, layer thickness 0.03mm, scanning spacing 0.1mm, scanning rotation increment 67°.

8. Application of the high temperature resistant titanium alloy according to claim 1 or the high temperature resistant titanium alloy prepared by the preparation method according to any one of claims 2 to 7 in the fields of aviation, aerospace and deep sea exploration.

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