Deformable Co-based ultrahigh-temperature high-hardness bearing alloy and preparation method thereof

Abstract

The invention relates to a deformable Co-based ultrahigh-temperature high-hardness bearing alloy and a preparation method thereof. The deformable Co-based ultrahigh-temperature high-hardness bearing alloy is prepared from the following chemical components in percentage by weight: 2.0 percent to 3.0 percent of C, 25.0 percent to 35.0 percent of Cr, 16.0 percent to 22.0 percent of W, 0.1 percent to 1.0 percent of Nb, 0.5 percent to 3.0 percent of Mo and the balance of Co and inevitable impurities. The novel Co-based alloy has the beneficial effects that the ultrahigh temperature, high hardness and high strength of the novel Co-based alloy are realized through the design of higher C, W and Cr, carbides and matrixes are regulated and controlled through the design of alloys such as Nb, the stability of a precipitated phase is improved, and meanwhile, the high-temperature deformability of the novel Co-based alloy is realized. The novel deformable Co-based high-temperature and high-hardness alloy is a novel bearing alloy material with potential, and is expected to solve the problem that the existing high-temperature bearing alloy is insufficient in strength and hardness when serving at the ultra-high temperature of 600-800 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature bearing materials, and in particular to a deformable Co-based ultra-high-temperature high-hardness bearing alloy and a preparation method thereof. Background Art

[0002] With the rapid development of aerospace, medical and other fields, the demand for high-temperature bearing materials with high temperature resistance and better performance is becoming more and more urgent. At present, the service temperature of typical high-temperature bearing steel does not exceed 600℃. When the service temperature exceeds 600℃, due to the degradation of organizational transformation, the hardness decreases and cannot meet the strength and hardness requirements of bearing materials. It is urgent to develop high-temperature and high-hardness alloys and materials.

[0003] At present, high-temperature materials in service above 600°C are mainly Ni-based alloys and Co-based high-temperature alloys. Taking the use of structural materials as an example, Ni-based high-temperature alloy structural materials are widely used. For example, the compressive yield strength of Inconel 718 at 800°C is only 750MPa. Most high-temperature structural materials focus on structural properties such as strength and plasticity. The high-temperature hardness is generally low and the wear performance is poor, which makes it difficult to meet the long-term service requirements of bearings with high stress loads.

[0004] Cobalt alloys with higher hardness, such as Stellite 20 alloy, have a hardness of only 245HV at ultra-high temperature of 800℃, and Stellite 100 alloy has the highest thermal hardness, which can reach 45HRC. They are non-deformable alloys and cannot be machined. They are often used for surface surfacing by surfacing welding. It is urgent to develop higher hardness, deformable Co-based ultra-high temperature and high hardness bearing alloys.

[0005] In summary, in response to the demand for high hardness, high temperature resistance and structural stability of ultra-high temperature bearing materials, the motivation for the invention is to develop a new deformable Co-based ultra-high temperature and high hardness bearing alloy. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a deformable Co-based ultra-high temperature and high hardness bearing alloy having high hardness, high strength and high plasticity and a preparation method thereof.

[0007] The present invention provides a deformable Co-based ultra-high temperature and high hardness bearing alloy and a preparation method thereof, and the technical scheme thereof is as follows:

[0008] A deformable Co-based ultra-high temperature and high hardness bearing alloy, the chemical composition of which comprises, by weight percentage, 2.0%-3.0% C, 25.0%-35.0% Cr, 16.0%-22.0% W, 0.1%-1.0% Nb, 0.5%-3.0% Mo, and the balance is Co and unavoidable impurities.

[0009] Furthermore, the chemical composition of the alloy includes, by weight percentage: C 2.3%-2.7%, Cr 28.0%-32.0%, W 18.0%-20.0%, Nb 0.3-0.8%, and Mo 1.0%-2.0%.

[0010] Furthermore, the microstructure of the bearing alloy includes an FCC matrix and a carbide precipitation phase with a granular and lamellar distribution of (W, Cr)7C3 structure.

[0011] Furthermore, the bearing alloy has a high temperature hardness of 48-54HRC at 800°C, and a compressive deformation of 27%-30% at 800°C and a compressive strength of 1460MPa.

[0012] Further, it is prepared by a vacuum arc melting method or a vacuum induction melting method.

[0013] Further, the method steps of vacuum arc melting Co-based ultra-high temperature and high hardness bearing alloy are as follows:

[0014] Step 1: According to the ratio of each element in the alloy, high-purity alloy raw materials are used for batching, and the prepared raw materials are placed in a vacuum arc melting furnace;

[0015] Step 2: Vacuum to 5×10 -3 After the pressure reaches -0.05 MPa, argon gas is introduced into the vacuum chamber to the chamber pressure of -0.05 MPa, and the raw materials are arc-melted. The alloy ingots at each station are kept for 1-3 minutes after being completely melted, and the melting temperature is kept between 1350-1400°C;

[0016] Step 3: In order to ensure the uniformity of the alloy composition, the ingot is turned over and melted 7-8 times, and repeated melting and solidification are performed to ensure the uniformity of the structure. After the melting is completed, it is cooled with a water-cooled copper mold.

[0017] Further, the method steps of vacuum induction melting Co-based ultra-high temperature and high hardness bearing alloy are as follows:

[0018] Step 1: According to the ratio of each element in the alloy, high-purity alloy raw materials are used for batching, and the ingredients, crucible and mold are cleaned to ensure the high purity of the alloy;

[0019] Step 2: Load the prepared raw materials into the vacuum induction melting furnace and evacuate to 5×10 -3 After Pa, electricity is sent to melt, the melting temperature is maintained between 1350-1400℃, and high-purity argon gas with a purity of not less than 99.9% is filled for protection. Auxiliary materials are added, and after refining, the temperature is reduced for casting. After the mold is cooled, the mold is removed and demolded.

[0020] The implementation of the present invention includes the following technical effects:

[0021] The new deformable Co-based ultra-high temperature and high hardness bearing alloy designed by the present invention realizes ultra-high temperature, high hardness and high strength of the new Co-based alloy through higher C, high W and high Cr design, and regulates carbides and matrix through Nb and other alloy design, improves the stability of the precipitated phase, and realizes its high temperature deformation ability at the same time. The new deformable Co-based high temperature and high hardness alloy is a potential new bearing alloy material, which is expected to solve the problem of insufficient strength and hardness of existing high temperature bearing alloys when serving at ultra-high temperatures of 600-800℃, and can greatly promote the rapid scale development of hot end materials and related industries. The ultra-high temperature bearing alloy has the superior performance of stable organization in ultra-high temperature range (room temperature to 800℃), high temperature and high hardness (high temperature hardness of 48-54HRC at 800℃), and high strength (compression deformation of 27%-30% under the condition of 1460MPa compression strength at 800℃). BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the typical structure of the deformable Co-based ultra-high temperature bearing alloy in Example 1 of the present invention.

[0023] Figure 2 This is a high temperature compressive stress-strain curve of the deformable Co-based ultra-high temperature bearing alloy according to Example 1 of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] A deformable Co-based ultra-high temperature and high hardness bearing alloy of this embodiment, the chemical composition of the alloy includes by weight percentage: C 2.0%-3.0%, Cr 25.0%-35.0%, W 16.0%-22.0%, Nb 0.1-1.0%, Mo0.5%-3.0%, the balance is Co and inevitable impurities, the alloy is based on Co, the microstructure of the bearing alloy includes FCC matrix, and granular and lamellar distribution of (W, Cr)7C3 structure of carbide precipitation phase. Further, the chemical composition of the alloy includes by weight percentage: C 2.3%-2.7%, Cr 28.0%-32.0%, W 18.0%-20.0%, Nb 0.3-0.8%, Mo 1.0%-2.0%. Through the design of higher C, high W, and high Cr, the new Co-based alloy can achieve ultra-high temperature, high hardness, and high strength. Through the design of Nb and other alloys, the carbides and matrix are regulated to improve the stability of the precipitated phase and achieve its high-temperature deformation ability. Due to the characteristics of high hardness, high strength, and high plasticity, the high-temperature hardness and strength of the Co-based alloy are improved, breaking through the problem of the existing high-temperature and high-hardness Co-based alloy that cannot be deformed, and solving the problem of the existing high-temperature bearing alloy's organizational stability, strength, and hardness when serving at ultra-high temperatures of 600℃-800℃.

[0026] Example 1

[0027] The preparation method of the deformable Co-based ultra-high temperature and high hardness bearing alloy provided in this embodiment has the following specific preparation steps:

[0028] Step 1: According to the ratio of each element in the alloy, high-purity alloy raw materials are used for batching, and the prepared raw materials are placed in a vacuum arc melting furnace.

[0029] Step 2: Vacuum 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 1-3 minutes after being completely melted, and the melting temperature is kept between 1350-1400℃.

[0030] Step 3: In order to ensure the uniformity of the alloy composition, the ingot is turned over and melted 7-8 times, and repeated melting and solidification are performed to ensure the uniformity of the structure. After the melting is completed, it is cooled with a water-cooled copper mold.

[0031] Table 1 lists the chemical composition and weight percentage of the deformable Co-based ultrahigh temperature bearing alloy of Example 1. It can be seen from Tables 2 and 3 that the present invention can realize the preparation of the Co-based ultrahigh temperature bearing alloy by controlling the composition. The prepared ultrahigh temperature bearing alloy has a stable structure in an ultrahigh temperature range (room temperature to 800°C), a room temperature hardness of 59-64HRC, and a high temperature hardness of 48-54HRC at 800°C; Figure 1It is a typical microstructure of the new alloy, including FCC structure Co-based solid solution and granular and lamellar distribution of (W / Cr)7C3 structure carbide precipitation phase. Figure 2 It can be seen from the high temperature compression curve of the alloy that sample 5 has the characteristics of high hardness, high strength and high plasticity with a compressive strength of 1460MPa and a compressive deformation of 27% at 800°C.

[0032] Table 1 Chemical composition of deformable Co-based ultrahigh temperature bearing alloy of Example 1, wt%

[0033]

[0034] Table 2 Room temperature hardness of deformable Co-based ultrahigh temperature bearing alloy of Example 1

[0035]

[0036] Table 3 800℃ high temperature hardness of deformable Co-based ultrahigh temperature bearing alloy of Example 1

[0037]

[0038] Example 2

[0039] The preparation method of the deformable Co-based ultra-high temperature and high hardness bearing alloy provided in this embodiment has the following specific preparation steps:

[0040] Step 1: According to the ratio of each element in the alloy, high-purity alloy raw materials are used for mixing, and the ingredients, crucible and mold are cleaned to ensure the high purity of the alloy.

[0041] Step 2: Load the prepared raw materials into the vacuum induction melting furnace and evacuate to 5×10 -3 After Pa, electricity is sent to melt, the melting temperature is maintained between 1350-1400℃, and high-purity argon gas with a purity of not less than 99.9% is filled for protection. Auxiliary materials are added, and after refining, the temperature is reduced for casting. After the mold is cooled, the mold is removed and demolded.

[0042] As shown in Table 4, the chemical composition and weight percentage test results of the deformable Co-based ultrahigh temperature bearing alloy of Example 2. As can be seen from Table 5, the present invention can realize the preparation of Co-based ultrahigh temperature bearing alloy through the combined control of composition and process, and the prepared ultrahigh temperature bearing alloy has a stable structure in an ultrahigh temperature range (room temperature to 800°C), a room temperature hardness greater than 60HRC, and a high temperature hardness of 800°C greater than 50HRC.

[0043] Table 4 Chemical composition of deformable Co-based ultrahigh temperature bearing alloy of Example 2, wt%

[0044]

[0045] Table 5 Room temperature and high temperature hardness of deformable Co-based ultrahigh temperature bearing alloy of Example 2

[0046]

[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. A deformable Co-based ultra-high temperature and high hardness bearing alloy, characterized in that: The chemical composition of the alloy includes, by weight percentage, C 2.0%-3.0%, Cr 25.0%-35.0%, W 16.0%-22.0%, Nb 0.1-1.0%, Mo 0.5%-3.0%, and the balance is Co and inevitable impurities.

2. The deformable Co-based ultra-high temperature and high hardness bearing alloy according to claim 1, characterized in that: The chemical composition of the alloy includes, by weight percentage: C 2.3%-2.7%, Cr 28.0%-32.0%, W 18.0%-20.0%, Nb 0.3-0.8%, and Mo 1.0%-2.0%.

3. The deformable Co-based ultra-high temperature and high hardness bearing alloy according to claim 1, characterized in that: The microstructure of the bearing alloy includes an FCC matrix and a carbide precipitation phase with a (W, Cr)7C3 structure distributed in a granular or lamellar manner.

4. The deformable Co-based ultra-high temperature and high hardness bearing alloy according to claim 1, characterized in that: The bearing alloy has a high temperature hardness of 48-54HRC at 800°C, and a compression deformation of 27%-30% at 800°C and a compression strength of 1460MPa.

5. The deformable Co-based ultra-high temperature and high hardness bearing alloy according to claim 1, characterized in that: Prepared by vacuum arc melting method or by vacuum induction melting method.

6. The deformable Co-based ultra-high temperature and high hardness bearing alloy according to claim 5, characterized in that: The method steps for vacuum arc melting Co-based ultra-high temperature and high hardness bearing alloy are as follows: Step 1: According to the ratio of each element in the alloy, high-purity alloy raw materials are used for batching, and the prepared raw materials are placed in a vacuum arc melting furnace; Step 2: Vacuum to 5×10 -3 After the pressure reaches -0.05 MPa, argon gas is introduced into the vacuum chamber to the chamber pressure of -0.05 MPa, and the raw materials are arc-melted. The alloy ingots at each station are kept for 1-3 minutes after being completely melted, and the melting temperature is kept between 1350-1400°C; Step 3: In order to ensure the uniformity of the alloy composition, the ingot is turned over and melted 7-8 times, and repeated melting and solidification are performed to ensure the uniformity of the structure. After the melting is completed, it is cooled with a water-cooled copper mold.

7. The deformable Co-based ultra-high temperature and high hardness bearing alloy according to claim 5, characterized in that: The method steps for vacuum induction melting of Co-based ultra-high temperature and high hardness bearing alloy are as follows: Step 1: According to the ratio of each element in the alloy, high-purity alloy raw materials are used for batching, and the ingredients, crucible and mold are cleaned to ensure the high purity of the alloy; Step 2: Load the prepared raw materials into the vacuum induction melting furnace and evacuate to 5×10 -3 After Pa, electricity is sent to melt, the melting temperature is maintained between 1350-1400℃, and high-purity argon gas with a purity of not less than 99.9% is filled for protection. Auxiliary materials are added, and after refining, the temperature is reduced for casting. After the mold is cooled, the mold is removed and demolded.

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