Ultrahigh-temperature bearing alloy and preparation method thereof

Abstract

The invention relates to an ultrahigh-temperature bearing alloy and a preparation method thereof. The ultrahigh-temperature bearing alloy is prepared from the following chemical components in percentage by weight: 0.02 percent to 4.0 percent of C, 16.0 percent to 19.0 percent of Cr, 30.0 percent to 35.0 percent of Mo, 30.0 percent to 34.0 percent of Nb, 16.5 percent to 18.5 percent of V and inevitable impurities, a matrix in a microstructure of the ultrahigh-temperature bearing alloy is a BCC crystal structure with high mixing entropy, and NbC and Nb / VC precipitated phases are uniformly distributed on the BCC matrix. The method has the beneficial effects that the stability of a high-temperature structure is guaranteed based on the entropy effect on thermodynamics, meanwhile, the high-temperature hardness and the high-temperature strength of the high-temperature bearing are improved through Nb / VC high-carbide strengthening, and the material service performance requirements of stable structure, high hardness and high wear resistance of the high-temperature bearing at a high temperature are met.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature bearing materials, and particularly to ultra-high temperature bearing alloys and their preparation methods. Background Art

[0002] With the rapid development of fields such as aerospace and medical treatment, the demand for high-temperature bearing materials with high temperature resistance and better performance is becoming increasingly urgent. Currently, the service temperature of high-temperature bearing steels represented by Cr14Mo4V does not exceed 524°C, while the service temperatures of 55 alloy and Cr40Al3Ti nickel-based high-temperature bearing alloys do not exceed 600°C. After the service temperature exceeds 600°C, the microstructure changes, and it cannot meet the service requirements of high strength and high hardness for bearing materials. There is an urgent need to develop new high-temperature-resistant bearing materials.

[0003] Refractory high-entropy alloys containing high-melting-point elements such as Mo, V, and Nb have become new potential materials for manufacturing components for extreme temperature service due to their high melting points, high strength, and high hardness.

[0004] Patent CN13088787A discloses a single-phase WNbMoTaZr-based refractory high-entropy alloy and its preparation method. Its elemental composition includes W, Nb, Mo, Ta, and Zr, and the molar ratio of W, Nb, Mo, Ta, and Zr is 1:1:1:1:0.1 - 0.5. The average hardness of the alloy is 546HV, the room temperature yield strength reaches 1584 Mpa, and the compression plasticity is about 8.4%. It has good thermal stability in the range from room temperature to 1400°C. However, its high-temperature strength and hardness data are not reported.

[0005] Patent CN114606424A discloses a high-strength and high-toughness Mo-Nb-Ta-Hf-Zr refractory high-entropy alloy and its preparation method. The expression of the Mo-Nb-Ta-Hf-Zr refractory high-entropy alloy is MoxNbyTazHfuZrv, where x, y, z, u, and v are the molar percentages of the elements, satisfying x + y + z + u + v = 1; among them: 0.05 < x < 0.3, 0.4 < y + z < 0.5, 0.25 < u + v < 0.45. The yield strength at 1000°C is 700 - 1100 MPa, and the compression strength is 770 - 1800 MPa. However, its high-temperature hardness data are not reported.

[0006] In summary, aiming at the characteristics of high hardness, high temperature resistance, and structural stability of high-temperature bearing materials, developing and preparing a new bearing alloy with high yield strength, high hardness, and high wear resistance at 1000°C is a technical problem that亟待解决 (urgently needs to be solved). Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide an ultra-high temperature bearing alloy with high yield strength, high hardness and high wear resistance and a preparation method thereof.

[0008] The ultra-high temperature bearing alloy provided by the present invention has the following technical solutions:

[0009] An ultra-high temperature bearing alloy, the chemical composition of which comprises, by weight percentage, C0.02%-4.0%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities; in the microstructure of the ultra-high temperature bearing alloy, the matrix is ​​a BCC crystal structure with high mixing entropy, and NbC and Nb / VC precipitated phases are uniformly distributed on the BCC matrix.

[0010] Furthermore, the volume percentage of NbC and Nb / VC precipitated phases on the BCC matrix is ​​0%-40%, and the average size of the NbC and Nb / VC precipitated phases is 3-30 μm.

[0011] Furthermore, the ultra-high temperature bearing alloy has a stable structure from room temperature to 1000°C, a room temperature hardness ≥58HRC, a high temperature hardness at 800°C ≥51HRC, and a high temperature hardness at 1000°C ≥49HRC.

[0012] Furthermore, the ultra-high temperature bearing alloy has a high temperature compressive strength of ≥2095 MPa and a compressive engineering strain of ≥20% at 800°C; and has a high temperature compressive strength of ≥1219 MPa and a compressive engineering strain of ≥30% at 1000°C.

[0013] Furthermore, the chemical composition of the alloy comprises, by weight percentage, C 0.02%-0.05%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0%-34.0%, V 16.5%-18.5% and inevitable impurities.

[0014] Furthermore, the chemical composition of the alloy comprises, by weight percentage, C 0.6-0.8%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities.

[0015] Furthermore, the chemical composition of the alloy comprises, by weight percentage, C 3.0-4.0%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities.

[0016] Furthermore, the alloy is prepared by vacuum induction melting method or vacuum arc melting method, and is repeatedly melted and solidified 8-10 times to ensure the uniformity of the structure.

[0017] Furthermore, the raw materials prepared according to the composition ratio were placed in a DHL400 high vacuum non-consumable arc furnace and evacuated to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc melted. The alloy ingot at each workstation is kept for 1 minute after being completely melted, and the melting temperature is maintained between 2100℃ and 2200℃. After the melting is completed, it is cooled with a water-cooled copper mold.

[0018] The implementation of the present invention includes the following technical effects:

[0019] The ultra-high temperature bearing alloy of the present invention ensures its high temperature structural stability based on the entropy effect in thermodynamics, and at the same time improves its high temperature hardness and high temperature strength through Nb / VC high carbide strengthening, so as to meet the service performance requirements of high temperature bearings with stable organizational structure, high hardness and high wear resistance at high temperature. The alloy based on the BCC matrix has the characteristics of ultra-high temperature (room temperature to 1000℃) stable organization, high temperature and high hardness (800℃ high temperature hardness ≥51HRC, 1000℃ high temperature hardness ≥49HRC), high strength (800℃ compression strength ≥2095MPa, 1000℃ compression strength ≥1219MPa), and high strength and plasticity. The new high entropy alloy is a potential new high entropy bearing alloy material, which solves the problem of insufficient strength and hardness of existing high temperature bearing alloys when serving at ultra-high temperatures of 800℃-1000℃, and can greatly promote the rapid scale development of hot end materials and related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a typical microstructure diagram of the ultra-high temperature bearing alloy obtained in Example 3.

[0021] Figure 2 This is a typical microstructure diagram of the ultra-high temperature bearing alloy obtained in Example 1.

[0022] Figure 3 This is a typical microstructure diagram of the ultra-high temperature bearing alloy obtained in Example 2.

[0023] Figure 4 This is a typical microstructure diagram of the ultra-high temperature bearing alloy obtained in Example 3.

[0024] Figure 5 The differential thermal analysis (DSC) curves of Example 1 and Example 2 are shown in FIG.

[0025] Figure 6 This is the high temperature compressive stress-strain curve of Example 2 at 800°C and 1000°C.

[0026] Figure 7 This is the high temperature compressive stress-strain curve of Example 3 at 800°C. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below in conjunction with embodiments and drawings. It should be pointed out that the described embodiments are only intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0028] Example 1

[0029] The chemical composition and weight percentage of the ultra-high temperature bearing alloy of this embodiment are: C 0.02%-0.05%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities. The preparation method is to put the raw materials prepared according to the component ratio into a DHL400 high vacuum non-consumable arc furnace, and evacuate to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc-melted. The alloy ingots of each station are kept for 1 minute after being completely melted. In order to ensure the uniformity of alloy composition, the ingots are turned over and melted 8-10 times. The melting temperature is kept between 2100℃-2200℃. After the melting is completed, the copper mold is cooled with water cooling. After the melting is completed, samples are taken to test the chemical composition and other tests are performed.

[0030] Example 2

[0031] The chemical composition and weight percentage of the ultra-high temperature bearing alloy of this embodiment are: C 0.6-0.8%, Cr16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities. The difference from Example 1 is that 0.6-0.8% C is added for alloying to improve its hardness and strength. The preparation method is to put the raw materials prepared according to the component ratio into a DHL400 high vacuum non-consumable arc furnace and evacuate to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc-melted. The alloy ingots of each station are kept for 1 minute after being completely melted. In order to ensure the uniformity of alloy composition, the ingots are turned over and melted 8-10 times. The melting temperature is kept between 2100℃-2200℃. After the melting is completed, the copper mold is cooled with water cooling. After the melting is completed, samples are taken to test the chemical composition and other tests are performed.

[0032] Example 3

[0033] The chemical composition and weight percentage of the ultra-high temperature bearing alloy of this embodiment are: C 3.0-4.0%, Cr16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities. Different from Examples 1 and 2, Example 3 adds 3.0-4.0% ultra-high content C element for alloying, which significantly improves its hardness and strength. The preparation method is to put the raw materials prepared according to the component ratio into a DHL400 high vacuum non-consumable arc furnace, evacuate to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc-melted. The alloy ingots of each station are kept for 1 minute after being completely melted. In order to ensure the uniformity of alloy composition, the ingots are turned over and melted 8-10 times. The melting temperature is kept between 2100℃-2200℃. After the melting is completed, the copper mold is cooled with water cooling. After the melting is completed, samples are taken to test the chemical composition and other tests are performed.

[0034] Example 4

[0035] The chemical composition and weight percentage of the ultra-high temperature bearing alloy of this embodiment are: C 1.0-2.0%, Cr17.0%-18.0%, Mo 34.0%-35.0%, Nb 30.0-31.0%, V 16.5%-18.5% and inevitable impurities. Different from Examples 1 and 2, Example 3 adds 3.0-4.0% ultra-high content C element for alloying, which significantly improves its hardness and strength. The preparation method is to put the raw materials prepared according to the component ratio into a DHL400 high vacuum non-consumable arc furnace, evacuate to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc-melted. The alloy ingots of each station are kept for 1 minute after being completely melted. In order to ensure the uniformity of alloy composition, the ingots are turned over and melted 8-10 times. The melting temperature is kept between 2100℃-2200℃. After the melting is completed, the copper mold is cooled with water cooling. After the melting is completed, samples are taken to test the chemical composition and other tests are performed.

[0036] Example 5

[0037] The chemical composition and weight percentage of the ultra-high temperature bearing alloy of this embodiment are: C 1.0-2.0%, Cr 18.0%-19.0%, Mo 30.0%-31.0%, Nb 33.0-34.0%, V 16.5%-18.5% and inevitable impurities. Different from Examples 1 and 2, Example 3 adds 3.0-4.0% ultra-high content C element for alloying, which significantly improves its hardness and strength. The preparation method is to put the raw materials prepared according to the component ratio into a DHL400 high vacuum non-consumable arc furnace, evacuate to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc-melted. The alloy ingots of each station are kept for 1 minute after being completely melted. In order to ensure the uniformity of alloy composition, the ingots are turned over and melted 8-10 times. The melting temperature is kept between 2100℃-2200℃. After the melting is completed, the copper mold is cooled with water cooling. After the melting is completed, samples are taken to test the chemical composition and other tests are performed.

[0038] Table 1 shows the chemical composition and weight percentage of the ultra-high temperature bearing alloys obtained in Examples 1-5.

[0039] Table 1 Chemical composition of ultra-high temperature bearing alloys of various embodiments, wt%

[0040]

[0041] Table 2 Room temperature hardness of ultra-high temperature bearing alloys of various embodiments, HRC

[0042]

[0043] Table 3 High temperature hardness of ultra-high temperature bearing alloy of Example 2, HRC

[0044]

[0045] As can be seen from Tables 2 and 3, the present invention can achieve an ultra-high temperature bearing alloy with uniform structure, high hardness and high strength and plasticity through component control, and produce a bearing alloy with stable structure in an ultra-high temperature range (room temperature to 1000°C), room temperature hardness ≥ 58HRC, 800°C high temperature hardness ≥ 51HRC, and 1000°C high temperature hardness ≥ 49HRC. It has the characteristics of high strength, high hardness, high strength and plasticity and stable structure.

[0046] Attached Figure 1 and attached Figure 4 This is a typical organization diagram of the ultrahigh temperature bearing alloy obtained in Example 3, wherein the volume percentage of the BCC matrix is ​​about 60%, the volume percentage of the NbC and Nb / VC precipitated phases is about 40%, and the average size is 30 μm. Figure 2This is a typical organization diagram of the ultrahigh temperature bearing alloy obtained in Example 1, which is a BCC matrix without obvious precipitation phase. Figure 3 This is a typical organization diagram of the ultrahigh temperature bearing alloy obtained in Example 2, which is a BCC matrix and NbC precipitation phase. The volume percentage of the precipitation phase is about 10%, and the average size is about 3 μm. Figure 5 The DSC curves of thermal differential analysis of Examples 1 and 2 show that the sample of Example 1 has a stable structure in the range of 0-1040°C and a precipitation transformation in the range of 1044-1100°C; the sample of Example 2 with the addition of the C element has a stable structure in the range of 0-1400°C, indicating that the obtained ultra-high temperature bearing alloy has high structural stability in the range of 0-1000°C. Figure 6 The high temperature compressive stress-strain curves at 800°C and 1000°C of Example 2 are shown. The ultra-high temperature bearing alloy has a high temperature compressive strength of 2095MPa and a compressive engineering strain of 20% at 800°C, and a compressive strength of 1219MPa and a compressive engineering strain of >30% at 1000°C, indicating that the ultra-high temperature bearing alloy has high strength and good plasticity at 800°C-1000°C. Figure 7 The high temperature compressive stress-strain curve of Example 3 at 800°C. With the increase of C element, the compressive strength is further improved, and the high temperature compressive strength at 800°C is 2328MPa and the compressive engineering strain is 24%. The above data can show that the high carbon ultra-high temperature bearing alloy has higher strength at high temperature and good plasticity. The data of other examples will not be repeated.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An ultra-high temperature bearing alloy, characterized in that: The chemical composition of the alloy includes, by weight percentage, C0.02%-4.0%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V16.5%-18.5% and inevitable impurities; in the microstructure of the ultra-high temperature bearing alloy, the matrix is ​​a BCC crystal structure with high mixing entropy, and NbC and Nb / VC precipitation phases are distributed on the BCC matrix.

2. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The volume percentage of NbC and Nb / VC precipitated phases on the BCC matrix is ​​0%-40%, and the average size of the NbC and Nb / VC precipitated phases is 3-30 μm.

3. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The ultra-high temperature bearing alloy has a stable structure from room temperature to 1000°C, a room temperature hardness of ≥58HRC, a high temperature hardness of 800°C of ≥51HRC, and a high temperature hardness of 1000°C of ≥49HRC.

4. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The ultra-high temperature bearing alloy has a high temperature compressive strength of ≥2095 MPa and a compressive engineering strain of ≥20% at 800°C; and has a high temperature compressive strength of ≥1219 MPa and a compressive engineering strain of ≥30% at 1000°C.

5. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The chemical composition of the alloy includes, by weight percentage, C 0.02-0.05%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities.

6. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The chemical composition of the alloy includes, by weight percentage, C 0.6-0.8%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities.

7. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The chemical composition of the alloy includes, by weight percentage, C 3.0-4.0%, Cr 16.0%-19.0%, Mo 30.0%-35.0%, Nb 30.0-34.0%, V 16.5%-18.5% and inevitable impurities.

8. The ultrahigh temperature bearing alloy according to claim 1, characterized in that: The alloy is prepared by vacuum induction melting or vacuum arc melting, and the alloy is repeatedly melted and solidified 8-10 times to ensure the uniformity of the structure.

9. The ultrahigh temperature bearing alloy according to claim 8, characterized in that: The raw materials prepared according to the composition ratio were placed in a DHL400 high vacuum non-consumable arc furnace and evacuated to 5×10 -3 Pa, argon gas is introduced into the vacuum chamber until the chamber pressure is -0.05MPa, and the raw materials are arc melted. The alloy ingot at each workstation is kept for 1 minute after being completely melted, and the melting temperature is maintained between 2100℃ and 2200℃. After the melting is completed, it is cooled with a water-cooled copper mold.

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