A rare earth-containing aviation bearing steel with excellent impact toughness and its preparation method

Abstract

The present invention belongs to the technical field of alloy materials, and particularly relates to a rare-earth-containing aviation bearing steel with excellent impact toughness and a preparation method thereof. The rare-earth-containing aviation bearing steel with excellent impact toughness has the following chemical components by mass percentage: C 0.80% - 0.85%, Mn 0.15% - 0.35%, Cr 4.00% - 4.25%, Mo 4.00% - 4.50%, V 0.90% - 1.10%, RE 0.04% - 0.09%, Ni 0.10% - 0.30%, Si 0.10% - 0.30%, W 0.20% - 0.50%, Nb 0.01% - 0.02%, Al 0.01% - 0.04%, P≤0.015%, S≤0.008%, and the balance is Fe and inevitable impurities. The rare-earth-containing aviation bearing steel of the present invention is prepared by vacuum induction melting, vacuum arc remelting, homogenization annealing, hot working, spheroidizing annealing, quenching, and two tempering treatments. The content of impurity elements is low, and the heat-treated material has fewer high-temperature carbides, higher hardness, and excellent impact toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy materials, and particularly relates to a rare-earth-containing aviation bearing steel with excellent impact toughness and a preparation method thereof. Background Art

[0002] Bearings are one of the most important key basic components in the equipment manufacturing industry and are known as the "joints of high-end equipment", being widely used in various industrial production fields. With the rapid development of high-end industrial fields such as high-speed rail trains and aerospace, the performance requirements for bearing materials by equipment are getting higher and higher. Especially during the high-speed rotation of aviation engine bearings, they not only have to bear the pressure of high loads but also withstand relatively high environmental temperatures. And after high-temperature tempering, the secondary hardening steel 8Cr4Mo4V can precipitate stable M 2 C carbides, which can meet the working environment below 350°C. Therefore, it has replaced the high-carbon chromium bearing steel GCr15 as the second-generation aviation bearing steel.

[0003] Although aviation bearing steels generally adopt a double-vacuum smelting process and have higher purity and compositional uniformity compared to traditional bearing steels, due to the high C, Cr, Mo, and V contents in the 8Cr4Mo4V bearing steel, a large number of large-sized primary carbides will precipitate during solidification, which are mainly Mo-rich metastable M 2 C primary carbides. Due to the large size of the primary carbides, fatigue cracks are likely to initiate and then propagate at the interface between the carbides and the matrix, ultimately leading to bearing fatigue failure. In addition, as the rotational speed of aviation engine bearings continues to increase and the DN value continues to increase, in addition to requiring the bearing steel to have high temperature resistance, high hardness, wear resistance, and high fatigue resistance, it is also required to have good impact resistance.

[0004] The purpose of the present invention is to provide a rare-earth-containing aviation bearing steel with excellent impact toughness and a preparation method thereof. By adding a certain content of elements to the existing 8Cr4Mo4V steel and adjusting its smelting, hot working, and heat treatment processes, dendrite segregation is reduced and the growth of primary carbides is inhibited, thereby improving its impact toughness. Summary of the Invention

[0005] The purpose of the present invention is to provide a rare-earth-containing aviation bearing steel with excellent impact toughness and a preparation method thereof, which not only has a small content of high-temperature carbides but also has high hardness and excellent impact toughness at the same time.

[0006] To achieve the above purpose, the main technical solutions adopted by the present invention include:

[0007] In the first aspect of the present invention, a rare earth-containing aviation bearing steel with excellent impact toughness is provided. By mass percentage, its chemical components are: C 0.80% - 0.85%, Mn 0.15% - 0.35%, Cr 4.00% - 4.25%, Mo 4.00% - 4.50%, V 0.90% - 1.10%, RE 0.04% - 0.09%, Ni 0.10% - 0.30%, Si 0.10% - 0.30%, W 0.20% - 0.50%, Nb 0.01% - 0.02%, Al 0.01% - 0.04%, P ≤ 0.015%, S ≤ 0.008%, and the balance is Fe and unavoidable impurities.

[0008] Preferably, the RE is a rare earth element, including one or more of lanthanum, cerium, and yttrium.

[0009] In some preferred embodiments, the RE is any one of lanthanum and cerium; further preferably, the RE is cerium and lanthanum, and the mass ratio is (2 - 3):1; even further, the RE is cerium, lanthanum, and yttrium, and the mass ratio is (10 - 12):(4 - 5):1.

[0010] Selecting specific rare earth elements can not only improve the impact toughness of the bearing steel but also enhance its fatigue resistance. This may be because on the one hand, the added rare earth elements can modify aluminum-containing inclusions to obtain rare earth oxysulfides and oxides, etc. Rare earth inclusions not only have a lower hardness than alumina, are not prone to crack initiation, and contribute to improving the impact toughness and fatigue resistance of the bearing steel, but can also precipitate at grain boundaries, hinder grain boundary migration, and thus refine the grains; on the other hand, rare earth elements can inhibit the growth of M 2 C carbides at high temperatures, which helps to reduce the size of primary carbides and improve the impact resistance of the bearing steel. In addition, adding rare earth can promote the dissolution of M 2 C carbides at high temperatures, reduce the quantity and area fraction of high-temperature carbides after quenching treatment, contribute to improving the impact resistance of the bearing steel, and at the same time can reduce the temperature during the quenching process, which helps to reduce the heat treatment cost. In actual experiments, the addition of one rare earth element can also show effects, but the addition of two or three or more rare earth elements has better effects, and there is a certain synergistic effect among them.

[0011] Preferably, the mass ratio of RE, Nb, and Al is (2.5 - 2.8):(0.3 - 0.6):1.

[0012] By regulating the mass ratio of RE, Nb, and Al, it is possible to refine the grain size, improve the impact toughness of bearing steel, and ensure its hardness at the same time. This may be because there is a synergistic effect among them. The combined action of RE, Nb, and Al can significantly refine the grains. RE promotes grain refinement by improving the distribution of inclusions, Nb by forming stable carbides, and Al by deoxidation. Fine and uniform grains can effectively prevent crack propagation, and the reduction of inclusions and grain refinement both contribute to improving the strength and impact toughness of the material. The refined grains and the formed carbides act together to increase the hardness of the material. The addition of RE improves the phase interface, and the presence of Nb and Al increases the number of hard phases, thus ensuring the hardness of bearing steel. In addition, the compounds of Nb and Al can maintain good stability at high temperatures and, in combination with rare earth elements, reduce the aggregation and growth of carbides at high temperatures, thereby improving the properties of the material at high temperatures.

[0013] Preferably, the mass ratio of RE, V, Ni, Cr, and Si is 1:(10 - 15):(2 - 3):(45 - 55):(2 - 3).

[0014] By regulating the mass ratio of RE, V, Ni, Cr, and Si, it is possible to further regulate the content of high-temperature carbides while improving hardness and impact toughness. This may be because these elements have a synergistic effect. Vanadium and chromium act together to control the formation and stability of carbides, while rare earth elements optimize their precipitation behavior, making the carbides finer and more dispersed, thus reducing the number and area fraction of high-temperature carbides. Nickel, rare earth elements, and silicon act together to promote grain refinement by providing heterogeneous nucleation sites and purifying the grain boundaries. This not only enhances the strength of the material but also improves its toughness. Vanadium, chromium, and nickel act together to not only form high-hardness VC carbides but also indirectly increase hardness by improving hardenability and matrix strength. Nickel and rare earth elements act together to synergistically improve the impact toughness of aviation bearing steel by directly increasing the plasticity and overall toughness of the material and indirectly reducing the risk of crack propagation by purifying the grain boundaries.

[0015] Preferably, the mass ratio of C, V, Mo, and W is (2.2 - 2.4):(2.7 - 2.8):(12 - 13):1.

[0016] By adjusting the mass ratio of C, V, Mo, and W, not only can the amount and grain size of high-temperature carbides be controlled, but also the hardness can be improved while the impact toughness is enhanced. This may be because carbon, vanadium, molybdenum, and tungsten act together in the formation process of carbides. By precisely controlling the carbon content and appropriately adding vanadium, molybdenum, and tungsten, the carbides can be made finer and more uniformly distributed, thereby reducing the types of unwanted high-temperature carbides and improving the thermal stability of the material. Molybdenum and tungsten refine the grains through solid solution strengthening. At the same time, the carbides formed by them and carbon act as heterogeneous nucleation sites, promoting the growth of finer and more uniform grains. The VC carbide formed by vanadium further refines the grain structure. Carbon is the basis for hardness improvement, and the high-hardness carbides formed by vanadium, molybdenum, and tungsten further enhance the hardness of the material. These hard phases not only provide a direct strength contribution but also indirectly enhance the hardness of the matrix by hindering dislocation movement. In addition, molybdenum and tungsten can also improve the overall toughness and impact resistance of the material through solid solution strengthening and grain refinement.

[0017] The second aspect of the present invention provides a preparation method of the rare-earth-containing aviation bearing steel with excellent impact toughness, including the following steps:

[0018] S1. Vacuum induction melting: The raw materials are subjected to vacuum induction melting according to the mass percentage of chemical components, and rare-earth elements are added 3 - 5 minutes before tapping and pouring.

[0019] S2. Vacuum arc remelting;

[0020] S3. Homogenization annealing: Keep at 1150 - 1250 °C for 7 - 9 h and then furnace cool to room temperature;

[0021] S4. Hot working: Keep at 1100 - 1150 °C for 0.5 h and then perform multi-directional forging. The final forging temperature is not lower than 950 °C, and then slow cool to room temperature;

[0022] S5. Spheroidizing annealing: Keep at 800 - 830 °C for 3 - 5 h, furnace cool to 530 - 550 °C and then air cool to room temperature;

[0023] S6. Quenching: Keep at 1090 - 1100 °C for 0.5 h and then air cool to 50 °C;

[0024] S7. Tempering: Keep at 520 - 530 °C for 2 - 3 h and then air cool to room temperature, repeat 2 - 3 times to obtain the rare-earth-containing aviation bearing steel.

[0025] Preferably, the specific conditions of the vacuum arc remelting are: melting current 2 - 3 kA, melting voltage 20 - 26 V, melting rate 1.0 - 1.5 kg / min.

[0026] Preferably, the multi-directional forging is three upsetting and three drawing.

[0027] Through a specific process, the various properties of aviation bearing steel are further improved, especially the impact toughness. First, in the vacuum induction melting and vacuum arc remelting stages, it is ensured that the raw materials are melted in a high-purity environment, effectively reducing the introduction of impurities and gases, improving the purity of the steel, and enhancing the overall toughness and mechanical properties of the material. Homogenization annealing helps to eliminate the microsegregation formed during the casting process, making the alloying elements more evenly distributed throughout the material, which is not only beneficial for subsequent processing but also improves the consistency of the mechanical properties of the final product. In the hot working stage, heat preservation at a specific temperature and the three-forging-three-drawing process are adopted. Compared with ordinary processes such as two-forging-two-drawing, the three-forging-three-drawing process can more effectively refine the grains and improve the organizational structure, thereby increasing the strength and toughness of the material; at the same time, a higher number of forging times can further reduce internal defects and improve the comprehensive performance of the material. Spheroidizing annealing promotes the spheroidization of carbides, forming more uniform and fine carbide particles dispersed on the matrix, which not only improves the cutting performance of the material but also enhances the toughness and reduces the risk of brittle fracture. Quenching makes the steel obtain a martensite structure, greatly improving the hardness and strength. Finally, two tempering treatments can effectively relieve the quenching stress, adjust the organizational structure, achieve the best balance between hardness and toughness, be more capable of stabilizing the microstructure of the material than one tempering, further improve the impact toughness, and ensure the long-term stability of the material properties.

[0028] For the rare earth-containing aviation bearing steel with excellent impact toughness, the area fraction of carbides in the quenched state is ≤1.6%, the room temperature hardness is ≥62 HRC, and the non-notch impact energy is ≥85 J.

[0029] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0030] 1. For the rare earth-containing aviation bearing steel with excellent impact toughness prepared by the present invention, by adding a certain content of elements to the existing 8Cr4Mo4V steel and adjusting its smelting, hot working, and heat treatment processes, dendrite segregation is reduced and the growth of primary carbides is inhibited, thereby improving its impact toughness.

[0031] 2. The rare earth elements added by the present invention can not only improve the impact toughness of the bearing steel but also improve its rolling contact fatigue life, and at the same time can reduce the temperature during the quenching process, which helps to reduce the heat treatment cost.

[0032] 3. By regulating the mass ratio of RE, Nb, and Al, the present invention can refine the grain size, improve the impact toughness of the bearing steel, and ensure its hardness at the same time.

[0033] 4. By regulating the mass ratio of RE, V, Ni, Cr, and Si, the present invention can further regulate the content of high-temperature carbides and improve the hardness and impact toughness at the same time.

[0034] 5. By regulating the mass ratio of C, V, Mo, and W, the present invention can not only regulate the amount and grain size of high-temperature carbides, but also improve hardness and impact toughness at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0036] Figure 1 Rare earth oxy-sulfide inclusions in the rare earth-containing aviation bearing steel with excellent impact toughness according to Embodiment 1 of the present invention.

[0037] Figure 2 Primary carbides with high Mo content in the rare earth-containing aviation bearing steel with excellent impact toughness according to Embodiment 1 of the present invention.

[0038] Figure 3 High-temperature carbides after quenching of the rare earth-containing aviation bearing steel with excellent impact toughness according to Embodiment 1 of the present invention.

[0039] Figure 4 Rare earth oxy-sulfide inclusions in the rare earth-containing aviation bearing steel with excellent impact toughness according to Embodiment 2 of the present invention.

[0040] Figure 5 Primary carbides with high Mo content in the rare earth-containing aviation bearing steel with excellent impact toughness according to Embodiment 2 of the present invention.

[0041] Figure 6 High-temperature carbides after quenching of the rare earth-containing aviation bearing steel with excellent impact toughness according to Embodiment 2 of the present invention.

[0042] Figure 7 Rare earth oxy-sulfide inclusions in the rare earth-containing aviation bearing steel with excellent impact toughness according to Comparative Example 1 of the present invention.

[0043] Figure 8 Primary carbides with high Mo content in the rare earth-containing aviation bearing steel with excellent impact toughness according to Comparative Example 1 of the present invention.

[0044] Figure 9 High-temperature carbides after quenching of the rare earth-containing aviation bearing steel with excellent impact toughness according to Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] Example 1

[0047] This embodiment provides a rare earth-containing aviation bearing steel with excellent impact toughness. By mass percentage, its chemical components are: C 0.83%, Mn 0.26%, Cr 4.24%, Mo 4.14%, V 0.95%, RE 0.079%, Ni 0.20%, Si 0.20%, W 0.35%, Nb 0.02%, Al 0.03%, P 0.0086%, S 0.0016%.

[0048] The RE is Ce.

[0049] The preparation method of the rare earth-containing aviation bearing steel with excellent impact toughness comprises the following steps:

[0050] S1. Vacuum induction melting: The raw materials are subjected to vacuum induction melting according to the mass percentage of the chemical components, and rare earth elements are added 5 minutes before tapping and pouring.

[0051] S2. Vacuum arc remelting;

[0052] S3. Homogenization annealing: Heat preservation is carried out at 1200 °C for 8 h, and then furnace cooling is carried out to room temperature.

[0053] S4. Hot working: Heat preservation is carried out at 1122 °C for 0.5 h, followed by three upsetting and three drawing processes, the final forging temperature is 950 °C, and slow cooling is carried out to room temperature.

[0054] S5. Spheroidizing annealing: Heat preservation is carried out at 817 °C for 4 h, furnace cooling is carried out to 538 °C, and then air cooling is carried out to room temperature.

[0055] S6. Quenching: Heat preservation is carried out at 1090 °C for 0.5 h, and then air cooling is carried out to 50 °C.

[0056] S7. Tempering: Heat preservation is carried out at 520 °C for 2 h, and then air cooling is carried out to room temperature, and this process is repeated twice to obtain the rare earth-containing aviation bearing steel.

[0057] The specific conditions for the vacuum arc remelting are: melting current 2.5 kA, melting voltage 24 V, and melting speed 1.2 kg / min.

[0058] Example 2

[0059] The differences between this embodiment and Embodiment 1 are as follows: For the rare-earth-containing aviation bearing steel with excellent impact toughness, by mass percentage, its chemical components are: C 0.80%, Mn 0.27%, Cr 4.20%, Mo 4.15%, V 0.93%, RE 0.076%, Ni 0.20%, Si 0.20%, W 0.35%, Nb 0.02%, Al 0.03%, P 0.0034%, S 0.0012%.

[0060] The said RE is Ce and La; the mass ratio is 55:21.

[0061] Embodiment 3

[0062] The differences between this embodiment and Embodiment 1 are as follows: For the rare-earth-containing aviation bearing steel with excellent impact toughness, by mass percentage, its chemical components are: C 0.83%, Mn 0.26%, Cr 4.24%, Mo 4.14%, V 0.95%, RE 0.08%, Ni 0.20%, Si 0.20%, W 0.35%, Nb 0.02%, Al 0.03%, P 0.0086%, S 0.0016%.

[0063] The said RE is Ce, La, and Y; the mass ratio is 11:4:1.

[0064] Comparative Example 1

[0065] The differences between this comparative example and Embodiment 1 are as follows: For the rare-earth-containing aviation bearing steel with excellent impact toughness, by mass percentage, its chemical components are: C 0.83%, Mn 0.25%, Cr 4.22%, Mo 4.11%, V 0.93%, Ni 0.20%, Si 0.20%, W 0.35%, Al 0.03%, P 0.0086%, S 0.0016%.

[0066] Comparative Example 2

[0067] The differences between this comparative example and Embodiment 1 are as follows: For the rare-earth-containing aviation bearing steel with excellent impact toughness, by mass percentage, its chemical components are: C 0.83%, Mn 0.26%, Cr 4.24%, Mo 4.14%, V 0.95%, RE 0.079%, Ni 0.20%, Si 0.20%, W 0.35%, Nb 0.02%, P 0.0086%, S 0.0016%.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that for the rare earth-containing aviation bearing steel with excellent impact toughness, by mass percentage, its chemical composition is: C 0.83%, Mn 0.26%, Cr 4.24%, Mo 4.14%, V 0.95%, RE 0.079%, Si 0.20%, W 0.35%, Nb 0.02%, Al 0.03%, P 0.0086%, S 0.0016%.

[0070] Comparative Example 4

[0071] The difference between this comparative example and Example 1 is that for the rare earth-containing aviation bearing steel with excellent impact toughness, by mass percentage, its chemical composition is: C 0.83%, Mn 0.26%, Cr 4.24%, Mo 4.14%, V 0.95%, RE 0.079%, Ni 0.20%, Si 0.20%, Nb 0.02%, Al 0.03%, P 0.0086%, S 0.0016%.

[0072] Comparative Example 5

[0073] The difference between this comparative example and Example 1 is that the preparation method of the rare earth-containing aviation bearing steel with excellent impact toughness comprises the steps of:

[0074] S1. Vacuum induction melting: The raw materials are subjected to vacuum induction melting according to the mass percentages of the chemical composition, and rare earth elements are added 5 minutes before tapping and pouring;

[0075] S2. Vacuum arc remelting;

[0076] S3. Homogenization annealing: After holding at 1200 °C for 8 h, furnace cooling to room temperature;

[0077] S4. Hot working: After holding at 1122 °C for 0.5 h, three upsetting and three drawing operations are carried out, and the final forging temperature is 950 °C, followed by slow cooling to room temperature;

[0078] S5. Spheroidizing annealing: Holding at 817 °C for 4 h, furnace cooling to 538 °C and then air cooling to room temperature;

[0079] S6. Quenching: Holding at 1090 °C for 0.5 h and then air cooling to 50 °C;

[0080] S7. Tempering: Holding at 520 °C for 2 h and then air cooling to room temperature to obtain the rare earth-containing aviation bearing steel.

[0081] Comparative Example 6

[0082] The difference between this comparative example and Example 1 is that the preparation method of the rare earth-containing aviation bearing steel with excellent impact toughness comprises the steps of:

[0083] S1. Vacuum induction melting: The raw materials are subjected to vacuum induction melting according to the mass percentages of chemical components, and rare earth elements are added 5 minutes before tapping and pouring.

[0084] S2. Vacuum arc remelting;

[0085] S3. Homogenization annealing: Keep at 1200 °C for 8 h and then furnace cool to room temperature;

[0086] S4. Hot working: Keep at 1122 °C for 0.5 h and then perform two upsetting and two drawing operations. The final forging temperature is 950 °C, and then slow cool to room temperature;

[0087] S5. Spheroidizing annealing: Keep at 817 °C for 4 h, furnace cool to 538 °C and then air cool to room temperature;

[0088] S6. Quenching: Keep at 1090 °C for 0.5 h and then air cool to 50 °C;

[0089] S7. Tempering: Keep at 520 °C for 2 h and then air cool to room temperature, repeat twice to obtain rare earth-containing aviation bearing steel.

[0090] Performance testing

[0091] Use a microscope to observe the rare earth oxysulfide inclusions, primary carbides with high Mo content, and high-temperature carbides after quenching in the bearing steels of Example 1, Example 2, and Comparative Example 1 respectively. The results are shown in Figures 1 to 3 、 Figures 4 to 6 、 Figures 7 to 9 . By comparing Figure 1 、 Figure 4 、 Figure 7 , it shows that the rare earth addition amount and addition method adopted in the present invention play a good role in modifying inclusions in the bearing steel.

[0092] Statistically analyze the average diameter and maximum diameter of the primary carbides in the as-cast bearing steel, with the unit of μm; statistically analyze the area fraction (unit: %) and number density of the high-temperature carbides in the quenched bearing steel (unit: mm 2 ); test the hardness (unit: HRC) and non-notch impact energy (unit: J, tested according to GB / T 229-2020 "Metallic materials - Charpy pendulum impact test method"). The results are shown in Table 1.

[0093] Table 1 Test results

[0094]

[0095] According to statistics, for the rare earth-containing aviation bearing steel prepared in Examples 1-3 of the present invention, the primary carbides are finer, and the quantity and volume of high-temperature carbides after heat treatment are smaller. At the same time, it has higher impact toughness and hardness. In Comparative Example 1, RE was not added; in Comparative Example 2, Al was not added; in Comparative Example 3, Ni was not added; in Comparative Example 4, W was not added; in Comparative Example 5, only one tempering was carried out; in Comparative Example 6, only two upsetting and two drawing processes were carried out. There are still differences in the various indexes of the prepared aviation bearing steel. Therefore, by adopting the method described in the present application, by adding a certain content of elements to the existing 8Cr4Mo4V steel and adjusting its smelting, hot working and heat treatment processes, dendritic segregation can be reduced and the growth of primary carbides can be inhibited, thereby improving its impact toughness and hardness.

[0096] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A rare earth-containing aviation bearing steel with excellent impact toughness, characterized in that: Calculated by mass percentage, its chemical composition is: C 0.80%~0.85%, Mn 0.15%~0.35%, Cr 4.00%~4.25%, Mo 4.00%~4.50%, V 0.90%~1.10%, RE 0.04%~0.09%, Ni 0.10%~0.30%, Si 0.10%~0.30%, W 0.20%~0.50%, Nb 0.01%~0.02%, Al0.01%~0.04%, P≤0.015%, S≤0.008%, and the balance is Fe and unavoidable impurities.

2. The rare earth-containing aviation bearing steel with excellent impact toughness according to claim 1, characterized in that: The RE is a rare earth element, including one or more of lanthanum, cerium, and yttrium.

3. The rare earth-containing aviation bearing steel with excellent impact toughness according to claim 1, characterized in that: The mass ratio of RE, Nb and Al is (2.5-2.8):(0.3-0.6):

1.

4. The rare earth-containing aviation bearing steel with excellent impact toughness according to claim 1, characterized in that: The mass ratio of RE, V, Ni, Cr and Si is 1:(10-15):(2-3):(45-55):(2-3).

5. The rare earth-containing aviation bearing steel with excellent impact toughness according to claim 1, characterized in that: The mass ratio of C, V, Mo and W is (2.2-2.4):(2.7-2.8):(12-13):

1.

6. The rare earth-containing aviation bearing steel with excellent impact toughness according to claim 1, characterized in that: The rare earth-containing aviation bearing steel with excellent impact toughness has a carbide area fraction in a quenched state of ≤1.6%, a room temperature hardness of ≥62 HRC, and a non-opening impact energy of ≥85 J.

7. A method for preparing rare earth-containing aviation bearing steel with excellent impact toughness according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Vacuum induction melting: The raw materials are subjected to vacuum induction melting according to the mass percentage of chemical components, and rare earth elements are added 3-5 minutes before steel pouring; S2, vacuum arc remelting; S3, homogenization annealing: keep at 1150-1250℃ for 7-9h and then cool to room temperature; S4, hot working: multi-directional forging after keeping at 1100-1150℃ for 0.5 h, the final forging temperature is not less than 950℃, and then slowly cooled to room temperature; S5, spheroidizing annealing: keep at 800-830℃ for 3-5h, furnace cool to 530-550℃ and then air cool to room temperature; S6, quenching: 1090~1100℃ for 0.5 h and then air-cool to 50℃; S7. Tempering: Keep at 520~530℃ for 2-3 hours, then air cool to room temperature, repeat 2-3 times to obtain rare earth-containing aviation bearing steel.

8. The method for preparing rare earth-containing aviation bearing steel with excellent impact toughness according to claim 7, characterized in that: The multi-directional forging is three-pier and three-draw.

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