Preparation method of high-pressure-resistant bearing rolling body and application thereof

Abstract

The application discloses a preparation method of a high-pressure-resistant bearing rolling body and application thereof, and belongs to the technical field of metallurgy, and solves the problem that fatigue cracks are prone to occurring in existing rolling bearings. The preparation method of the high-pressure-resistant bearing rolling body comprises the following steps: adding a first portion of alloy into an initial smelting furnace to perform initial smelting to obtain crude smelting liquid, transferring the crude smelting liquid into a refining furnace, adding a second portion of alloy to perform refining treatment, performing vacuum degassing and purification treatment on the smelting liquid after refining to remove gas and inclusions in the smelting liquid, performing solidification on the smelting liquid after the purification treatment to obtain a continuous casting blank, performing rolling, annealing and cold upsetting on the continuous casting blank to obtain a preformed blank, performing quenching and tempering on the preformed blank, and then performing finishing and surface protection treatment to obtain the bearing rolling body. The bearing rolling body prepared by the application is free of large-size inclusions and free of serious strip-shaped and net-shaped carbide aggregation, and the crushing load value of the finished bearing rolling body is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for preparing high-pressure bearing rolling elements and their application. Background Technology

[0002] The fatigue life and load-carrying capacity of rolling bearings largely depend on the performance of rolling elements, such as steel balls. Crushing load value is a key indicator of the rolling element's resistance to failure; failure to meet this value will directly lead to premature bearing damage. In existing technologies, the crushing load value of steel used for bearing rolling elements is insufficient, primarily due to microscopic defects within and on the surface of the material. These defects mainly include three aspects: first, large-sized brittle inclusions, especially spherical calcium aluminates and other non-deformable inclusions, which easily become crack initiators under heat treatment and stress; second, carbide inhomogeneity, including large carbide particles and severe carbide banding, leading to stress concentration and weakening matrix continuity; and third, surface and subsurface defects, such as folds and microcracks generated or evolving during drawing, cold heading, and grinding. These three defects make rolling bearings prone to fatigue cracking. Summary of the Invention

[0003] In view of the above problems, the purpose of this invention is to provide a method for preparing rolling elements of high-pressure bearings and its application, which solves the problem that existing rolling bearings are prone to fatigue cracks.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: a method for preparing a high-pressure-resistant bearing rolling element, comprising the following steps: S1: When the steel is tapped from the primary refining furnace, the first part of the alloy is added for rough composition adjustment to obtain crude steel liquid. The crude steel liquid is then transferred to the refining furnace, where the second part of the alloy is added for fine composition adjustment and removal of inclusions for refining. The refined steel liquid is then subjected to vacuum degassing purification treatment to remove gas and inclusions from the steel liquid. S2: Solidify the molten steel after purification in S1 to obtain a continuously cast billet; S3: The continuously cast billet is rolled, annealed, and cold-headed to obtain a preformed billet; S4: After quenching and tempering the preformed blank, perform precision machining and surface protection treatment to obtain the bearing rolling elements.

[0005] In some embodiments, the mass ratio of the first alloy to the second alloy in S1 is (70-95):(5-30), the mass fraction of oxygen content at the end of the primary refining furnace is ≤0.035%, the mass fraction of carbon content is 0.08%-0.68%, the mass fraction of nitrogen content is 0.001%-0.008%, and the temperature is 1580-1680℃.

[0006] In some embodiments, the vacuum degree is ≤0.3 kPa, the vacuum treatment time is 20-50 min, the mass fraction of oxygen content in the purified molten steel is ≤0.0006%, the mass fraction of nitrogen content is ≤0.005%, the Ca / Al activity ratio is ≤0.65, the Mg / Al activity ratio is ≤0.45, and the [Ti][N] concentration product is ≤7.5 × 10⁻⁶. -6 The size of metal oxides in the purified molten steel is ≤30μm; the size of nitrides is ≤15μm.

[0007] In some embodiments, S2 specifically involves using superheat control, electromagnetic stirring, and light reduction to perform low-segregation continuous casting of the purified molten steel to obtain a continuously cast billet; the superheat of the continuous casting process is 10-40℃, the electromagnetic stirring is used to make the flow velocity of the molten steel 0.2-0.6 m / s, and the light reduction rate is 3%-15%.

[0008] In some embodiments, S3 specifically refers to the continuous casting billet having an initial rolling temperature of 950-1150℃ and a final rolling temperature of 750-920℃, cooling the rolled billet to obtain a rolled material, and subjecting the rolled material to spheroidizing annealing, pickling and phosphating, cold drawing, cold upsetting, removal of the ring band, and soft grinding to obtain a preformed billet.

[0009] In some embodiments, the diameter of the rolled material is <15mm, and the corresponding final rolling temperature is 750-850℃; the diameter of the rolled material is ≥15mm, and the corresponding final rolling temperature is 850-920℃.

[0010] In some embodiments, the rolled billet is cooled in stages. When the temperature of the rolled billet is 650~900℃, the cooling rate is >20℃ / s; when the temperature is 500-650℃, the cooling rate is ≤15℃ / s. The rolled material has a network carbide grade ≤2 and a sorbite ratio ≥90%.

[0011] In some embodiments, the spheroidizing annealing includes a heating stage, an isothermal stage, and a slow cooling stage. The temperature of the heating stage is 770-810°C, and the time is 4-10 hours. The temperature of the isothermal stage is 690-720°C, and the time is 3-8 hours. The temperature of the slow cooling stage is ≤600°C. The protective atmosphere is a nitrogen-hydrogen mixture or a gas obtained by catalytic cracking of hydrocarbons and air. The decarburization of the rolled material surface after the spheroidizing annealing is ≤0.05 mm.

[0012] In some embodiments, step S4 specifically involves performing graded quenching and tempering on the preformed blank to obtain the bearing rolling element. The quenching temperature is 835-855℃, the quenching holding time is calculated based on the critical path length of heat transfer during the heat treatment of the bearing rolling element and is set to 1.0-1.5 min / mm, the tempering temperature is 150-230℃, and the tempering time is 2-4 h.

[0013] Another technical solution of the present invention is as follows: the high-pressure bearing rolling elements prepared by the method are applied in metallurgy, rail transportation, wind power equipment, processing equipment, and aerospace and defense equipment.

[0014] Compared with the prior art, the clean and uniform matrix prepared by the present invention makes the heat treatment effect more stable. The combination of good surface quality and strong and tough matrix structure makes it difficult for cracks to initiate and propagate when the bearing rolling elements are subjected to extremely high contact stress, thereby achieving a systematic and significant improvement in crushing load value. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a scanning electron microscope image of a steel ball fragment provided in Embodiment 1 of the present invention; Figure 2 A scanning electron microscope image of the crack source of the steel ball fragment provided in Embodiment 5 of the present invention; Figure 3 Another scanning electron microscope image of the crack source of the steel ball fragment provided in Embodiment 5 of the present invention; Figure 4 A scanning electron microscope image of the crack source of the steel ball fragment provided in Embodiment 6 of the present invention; It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0019] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0020] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0021] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] Example 1 Producing precision steel balls made of GCr15 steel with a diameter of 30.162mm. The final oxygen content in the primary refining furnace is 0.026% by mass, the carbon content is 0.11% by mass, and the nitrogen content is 0.0035% by mass. The tapping temperature is 1600℃. Ferrochrome, ferrosilicon, ferromanganese, and carbon powder are added during tapping for rough composition adjustment, with the added alloy accounting for 90% of the total alloy content. The intense stirring during tapping ensures the alloy melts rapidly and evenly and distributes throughout the ladle, achieving initial fine-tuning of the composition to obtain the rough molten steel. This rough molten steel is then transferred to the refining furnace where ferrochrome, ferrosilicon, ferromanganese, and carbon powder are added for refining, with the added alloy accounting for 10% of the total alloy content. To suppress the formation of large-sized spherical calcium aluminate inclusions and titanium nitride inclusions, vacuum degassing and purification treatment was performed on the refined molten steel to remove gases and inclusions. Vacuum degassing was achieved using either vacuum circulation or vacuum degassing, with a vacuum degree of 0.266 kPa and a treatment time of 25 min. This resulted in an oxygen content of 0.000042% by mass, a nitrogen content of 0.0038% by mass, a titanium content of 0.0012% by mass, a Ca / Al activity ratio of 0.1, a Mg / Al activity ratio of 0.05, and a [Ti][N] concentration product of 5 × 10⁻⁶. -6 The mass fractions of CaO and MgO in the inclusions are 25%, the mass fraction of Al2O3 is 75%, the maximum size of the metal oxides is 10 μm, and the maximum size of TiN is 8 μm. After purification, the superheat of the molten steel was 25℃, the electromagnetic stirring current was 300A, the frequency was 1.5Hz, and the light reduction rate was 6%. The carbon segregation index of the continuously cast billet was 1.06 after low segregation continuous casting. The initial rolling temperature of the continuously cast billet is 1050℃, the diameter of the rolled material to be obtained is 21mm, the final rolling temperature is set at 870℃, after rolling, it is rapidly cooled to 650℃ and then slowly cooled. The rapid cooling rate is 30℃ / s, and the slow cooling rate is 5℃ / s. The network carbides of the rolled material are grade 2, and the sorbite ratio is 95%. The hot-rolled material is subjected to surface eddy current testing and grinding, and the surface defect is 0.01mm. Isothermal spheroidizing annealing is carried out under a nitrogen-hydrogen protective atmosphere. The heating stage temperature is 790℃ for 8 hours, the isothermal stage temperature is 710℃ for 7 hours, the slow cooling rate is 10℃ / h, and the protective atmosphere is a nitrogen-hydrogen mixture. Spheroidized structure is obtained, and the surface decarburization is 0.02mm. After pickling, phosphating, cold drawing, cold heading, removal of ring bands, and soft grinding, a preformed billet is obtained. The material was austenitized at 840℃ in a controlled atmosphere quenching furnace, followed by staged quenching and finally tempering at 200℃ for 3 hours. The carbon content in the martensite was 0.45% by mass. Finishing and surface protection treatments included hard grinding, lapping, polishing, and cleaning for rust prevention. After finishing and surface protection, a uniform and fine spherical pearlite structure was obtained, with a banded structure grade of 1.5 and a network structure grade of 1.5. Surface decarburization was 0.04 mm. Simultaneously, online flaw detection and grinding were performed on the rolled material surface to ensure no deep-scale surface defects, with surface defects of 0.01 mm. Performance testing: Crushing load testing was conducted according to Appendix A of GB / T 24605-2021 "Rolling Bearing Product Marking". The results showed that the average crushing load value of the steel ball in Example 1 was 820 kN. Scanning electron microscopy characterization of the crushed fragments from Example 1 yielded the following results: Figure 1 As can be seen from the photographs shown, the fragments of Example 1 do not have obvious crack sources.

[0023] Example 2 Producing precision steel balls made of GCr15 steel with a diameter of 12.303mm. The initial refining, refining, vacuuming, and solidification processes of the molten steel were consistent with those in Example 1. The subsequent continuous casting billets produced using the same process had an initial rolling temperature of 1050°C, a required diameter of 9mm, and a final rolling temperature of 820°C. After rolling, the billets were rapidly cooled to 650°C followed by slow cooling at a rate of 30°C / s and 5°C / s. The rolled material had a network carbide grade of 1.5 and a sorbite content of 95%. The hot-rolled material underwent surface eddy current testing and grinding, resulting in a surface defect of 0.01mm. Isothermal spheroidizing annealing was performed under a nitrogen-hydrogen protective atmosphere. The heating stage was at 790°C for 6 hours, and the isothermal stage was at 710°C for 5 hours, with a slow cooling rate of 10°C / h. The protective atmosphere was a nitrogen-hydrogen mixture, resulting in a spheroidized structure with 0.01mm of surface decarburization. After pickling, phosphating, cold drawing, cold heading, removal of the ring band, and soft grinding, a pre-formed billet was obtained. The steel ball underwent austenitization at 840℃ in a controlled atmosphere quenching furnace, followed by staged quenching and finally tempering at 200℃ for 3 hours. The carbon content in the martensite was 0.45% by mass. Finishing and surface protection treatments included hard grinding, lapping, polishing, and cleaning for rust prevention. After finishing and surface protection, a uniform, fine spherical pearlite structure was obtained, with a banded structure grade of 1.0 and a network structure grade of 1.5. Surface decarburization was 0.03 mm. Simultaneously, online flaw detection and grinding were performed on the rolled material surface to ensure no deep-scale surface defects, with surface defects of 0.01 mm. Performance testing: Crushing load testing was conducted according to Appendix A of GB / T 24605-2021 "Rolling Bearing Product Marking". The results showed that the average crushing load value of the steel ball in Example 2 was 165 kN.

[0024] Example 3 Producing precision steel balls made of GCr15 steel with a diameter of 12.303mm. The primary refining, refining, vacuuming, solidification, and rolling processes of the molten steel are the same as in Example 2. The difference is that the protective gas for the subsequent spheroidizing annealing is a reducing gas obtained by catalytic cracking of natural gas and air. The temperature of the heating stage is 790°C and the time is 6 hours. The temperature of the isothermal stage is 710°C and the time is 5 hours. The slow cooling rate is 10°C / h. The protective atmosphere is a nitrogen-hydrogen mixture. A spheroidized structure is obtained with 0.02 mm of surface decarburization. After pickling, phosphating, cold drawing, cold heading, removal of the ring band, and soft grinding, a preformed blank is obtained. The steel ball underwent austenitization at 840℃ in a controlled atmosphere quenching furnace, followed by staged quenching and finally tempering at 200℃ for 3 hours. The carbon content in the martensite was 0.45% by mass. Finishing and surface protection treatments included hard grinding, lapping, polishing, and cleaning for rust prevention. After finishing and surface protection, a uniform, fine spherical pearlite structure was obtained, with a banded structure grade of 1.0 and a network structure grade of 1.5. Surface decarburization was 0.04 mm. Simultaneously, online flaw detection and grinding were performed on the rolled material surface to ensure no deep-scale surface defects, with surface defects of 0.02 mm. Performance testing: Crushing load testing was conducted according to Appendix A of GB / T 24605-2021 "Rolling Bearing Product Marking". The results showed that the average crushing load value of the steel ball in Example 3 was 158 kN.

[0025] Example 4 Producing precision steel balls made of GCr15 steel with a diameter of 12.303mm. The initial refining, refining, vacuuming, solidification, rolling, and preforming of the steel blank were the same as in Example 3. The difference was that the austenitizing temperature in the controlled atmosphere quenching furnace was 830℃, followed by staged quenching, and finally tempering at 180℃ for 3 hours. The carbon content in the martensite was 0.40%. Finishing and surface protection treatments included hard grinding, lapping, polishing, and cleaning for rust prevention. After finishing and surface protection treatments, a uniform and fine spherical pearlite structure was obtained, with a banded structure grade of 1.0 and a network structure grade of 1.5. The surface decarburization was 0.04 mm. Simultaneously, online flaw detection and grinding were performed on the surface of the rolled material to ensure no deep-scale surface defects, with surface defects of 0.02 mm. Performance testing: Crushing load tests were conducted according to Appendix A of GB / T 24605-2021 "Rolling Bearing Product Marking". The results showed that the average crushing load value of the steel ball in Example 4 was 220 kN.

[0026] Example 5 Producing precision steel balls made of GCr15 steel with a diameter of 30.162mm. The final oxygen content in the primary refining furnace is 0.030% by mass, the carbon content is 0.08% by mass, and the nitrogen content is 0.0035% by mass. The tapping temperature is 1580℃. Ferrochrome, ferrosilicon, ferromanganese, and carbon powder are added during tapping for rough composition adjustment, with the added alloy accounting for 60% of the total alloy content, to achieve preliminary composition fine-tuning and obtain crude steel liquid. The crude steel liquid is then transferred to the refining furnace and ferrochrome, ferrosilicon, ferromanganese, and carbon powder are added for refining treatment, with the added alloy accounting for 40% of the total alloy content. Vacuum degassing is performed using vacuum circulation, and the vacuum degree is 0. The vacuum treatment time was 25 min at 266 kPa. The mass fraction of oxygen in the molten steel was 0.0065%, the mass fraction of nitrogen was 0.0045%, and the mass fraction of titanium was 0.002%. The Ca / Al activity ratio in the crude molten steel was 0.4, the Mg / Al activity ratio was 0.03, the mass fraction of CaO and MgO in the inclusions was 45%, the mass fraction of Al2O3 was 55%, the maximum size of the metal oxides was 130 μm, and the maximum size of TiN was 15 μm. The subsequent processes were the same as in Example 1.

[0027] Performance testing: Crushing load testing was conducted according to Appendix A of GB / T 24605-2021 "Rolling Bearing Product Marking". The results showed that the average crushing load value of the steel ball in Example 5 was 625 kN. Scanning electron microscopy characterization of the crushed fragments from Example 5 revealed obvious crack initiations, which were large inclusions reaching 130 micrometers in size. Figure 2 , Figure 3 As shown.

[0028] Example 6 Produces precision steel balls made of GCr15 steel with a diameter of Φ30.162mm.

[0029] The process parameters of Example 6 are completely the same as those of Example 1. The only difference is that the surface of the rolled material was not inspected and ground online, and the absence of deep-scale surface defects was not ensured.

[0030] Performance testing: Crushing load tests were conducted according to Appendix A of GB / T 24605-2021 "Rolling Bearing Product Marking". The results showed that the average crushing load value of the steel ball in Example 6 was 515 kN. Scanning electron microscopy characterization of the crushed fragments from Example 6 revealed obvious crack initiations, which were surface defects, such as... Figure 4 As shown.

[0031] The crushing load value of the steel ball prepared in Example 1 was increased by approximately 31.2% compared to Example 5 and by 59.2% compared to Example 6. Furthermore, the crushing load value data of the product in Example 1 showed a more concentrated distribution and a smaller coefficient of variation, exhibiting excellent stability. Metallographic analysis indicated that the number of large-sized DS-type inclusions in the product of this invention was reduced by 20%, the steel ball surface was defect-free, and the average size of carbide particles was ≤0.6μm. Metallographic observation at 200x and 500x magnification showed that banded carbides were rated 1-2, and network carbides were rated 1-2.5, with hardness fluctuation within the same batch ≤1HRC.

[0032] This invention controls the composition and morphology of inclusions from the smelting stage, modifying them into fine, deformable, and advantageous inclusions, fundamentally reducing the risk of early failure caused by large-sized brittle inclusions. Through low-segregation continuous casting and controlled rolling and cooling, carbon segregation and carbide aggregation are effectively reduced, resulting in a uniform pre-structure that creates optimal conditions for subsequent spheroidizing annealing, ultimately yielding a highly uniform microstructure. Active control of surface quality after rolling reduces defects in the original material; and optimized quenching and tempering processes control heat treatment stress, preventing the generation and deterioration of surface and subsurface defects during processing. A clean and uniform matrix ensures more stable heat treatment results. The combination of good surface quality and a strong and tough matrix structure makes it difficult for cracks to initiate and propagate when the rolling element is subjected to extremely high contact stress, thus achieving a systematic and significant improvement in crushing load values.

[0033] It should be understood that the above are merely illustrative examples and do not constitute any limitation on the technical solutions of the present invention. In specific applications, those skilled in the art can make settings as needed, and the present invention does not impose any restrictions on this.

[0034] It should be noted that the steps described above are merely illustrative and do not limit the scope of protection of this invention. In practical applications, those skilled in the art can select some or all of them to achieve the purpose of this embodiment according to actual needs, and no restrictions are imposed here. The steps of the method described in this application are not limited to being executed sequentially according to the order in the specification; without changing the core technical solution, the execution order of some steps can be adjusted, or they can be implemented in parallel, or steps can be omitted or added in different scenarios. The above modifications or equivalent substitutions do not affect the substantive content of the technical solution of this application and should all fall within the scope of protection of this application.

[0035] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. The scope of protection of this application should be determined by the scope of the claims. Although this application has disclosed the preferred embodiment above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall fall within the scope of the technical solution of this application.

Claims

1. A method for preparing rolling elements of a high-pressure bearing, characterized in that, Includes the following steps: S1: When the steel is tapped from the primary refining furnace, the first part of the alloy is added for rough composition adjustment to obtain crude steel liquid. The crude steel liquid is then transferred to the refining furnace, where the second part of the alloy is added for fine composition adjustment and removal of inclusions for refining. The refined steel liquid is then subjected to vacuum degassing purification treatment to remove gas and inclusions from the steel liquid. S2: Solidify the molten steel after purification in S1 to obtain a continuously cast billet; S3: The continuously cast billet is rolled, annealed, and cold-headed to obtain a preformed billet; S4: After quenching and tempering the preformed blank, perform precision machining and surface protection treatment to obtain the bearing rolling elements.

2. The method for preparing high-pressure bearing rolling elements according to claim 1, characterized in that, The mass ratio of the first alloy to the second alloy in S1 is (70-95):(5-30). The mass fraction of oxygen content at the end of the primary refining furnace is ≤0.035%, the mass fraction of carbon content is 0.08%-0.68%, the mass fraction of nitrogen content is 0.001%-0.008%, and the temperature is 1580-1680℃.

3. The method for preparing high-pressure bearing rolling elements according to claim 2, characterized in that, The vacuum degree is ≤0.3 kPa, the vacuum treatment time is 20-50 min, the mass fraction of oxygen content in the purified molten steel is ≤0.0006%, the mass fraction of nitrogen content is ≤0.005%, the Ca / Al activity ratio is ≤0.65, the Mg / Al activity ratio is ≤0.45, and the [Ti][N] concentration product is ≤7.5 × 10⁻⁶. -6 The size of metal oxides in the purified molten steel is ≤30μm; the size of nitrides is ≤15μm.

4. The method for preparing high-pressure bearing rolling elements according to claim 1, characterized in that, S2 specifically involves using superheat control, electromagnetic stirring, and light reduction to perform low-segregation continuous casting of the purified molten steel to obtain a continuously cast billet; the superheat of the continuous casting process is 10-40℃, the electromagnetic stirring makes the flow velocity of the molten steel 0.2-0.6 m / s, and the light reduction rate is 3%-15%.

5. The method for preparing high-pressure bearing rolling elements according to claim 4, characterized in that, Specifically, S3 involves setting the initial rolling temperature of the continuously cast billet to 950-1150℃ and the final rolling temperature to 750-920℃. The rolled billet is then cooled to obtain a rolled material, which is then subjected to spheroidizing annealing, pickling and phosphating, cold drawing, cold upsetting, removal of the ring band, and soft grinding to obtain a preformed billet.

6. The method for preparing high-pressure bearing rolling elements according to claim 5, characterized in that, The diameter of the rolled material is <15mm, and the corresponding final rolling temperature is 750-850℃; the diameter of the rolled material is ≥15mm, and the corresponding final rolling temperature is 850-920℃.

7. The method for preparing high-pressure bearing rolling elements according to claim 5, characterized in that, The rolled billet is cooled in stages. When the temperature of the rolled billet is 650~900℃, the cooling rate is >20℃ / s; when the temperature is 500-650℃, the cooling rate is ≤15℃ / s. The network carbides of the rolled material are ≤2 grade, and the sorbite ratio is ≥90%.

8. The method for preparing high-pressure bearing rolling elements according to claim 5, characterized in that, The spheroidizing annealing includes a heating stage, an isothermal stage, and a slow cooling stage. The temperature of the heating stage is 770-810℃, and the time is 4-10h. The temperature of the isothermal stage is 690-720℃, and the time is 3-8h. The temperature of the slow cooling stage is ≤600℃. The protective atmosphere is a nitrogen-hydrogen mixture or a gas obtained by catalytic cracking of hydrocarbons and air. The decarburization of the rolled material surface after the spheroidizing annealing is ≤0.05mm.

9. The method for preparing high-pressure bearing rolling elements according to any one of claims 1-8, characterized in that, S4 specifically involves performing graded quenching and tempering on the preformed blank to obtain the bearing rolling element. The quenching temperature is 835-855℃, and the quenching holding time is calculated based on the critical path length of heat transfer during the heat treatment of the bearing rolling element and set to 1.0-1.5 min / mm. The tempering temperature is 150-230℃, and the tempering time is 2-4 h.

10. Applications of high-pressure bearing rolling elements prepared by any one of claims 1-9 in metallurgy, rail transportation, wind power equipment, processing equipment, and aerospace and defense equipment.

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