High-efficiency and precise Marbe multiphase heat treatment method for high-carbon steel bearings

Abstract

This application provides a highly efficient and precise multiphase heat treatment method for high-carbon steel bearings, relating to the field of bearing manufacturing technology. The method includes: controlling the austenitization process using target austenitization process parameters to obtain target austenite; controlling the transformation of the target austenite phase into target bainite using a staged isothermal quenching process; determining the first-stage isothermal quenching process parameters based on the target bainite nucleation parameters during the first-stage isothermal quenching process; determining the second-stage isothermal quenching process parameters based on the target bainite growth parameters during the second-stage isothermal quenching process; and determining the third-stage isothermal quenching process parameters based on the target bainite volume fraction parameters during the third-stage isothermal quenching process. This application enables precise control of the phase ratio and morphology of the multiphase microstructure while rapidly forming bainite in rolled bearing steel.

Description

Technical Field

[0001] This invention relates to the field of bearing manufacturing technology, and more specifically, to a high-efficiency and precise Marbe multiphase heat treatment method for high-carbon steel bearings. Background Technology

[0002] Bearings are core components of mechanical equipment, directly affecting the service performance and lifespan of high-end equipment such as high-end CNC machine tools, civil aviation engines, and high-speed motors. High-carbon chromium bearing steel is often used as the matrix material for bearing rings because of its excellent formability and high hardness, good wear resistance, and contact fatigue performance after quenching and tempering. Multiphase heat treatment is a commonly used process for high-carbon chromium bearings. This involves isothermal quenching the rings in the lower bainite transformation temperature range after austenitization to generate some lower bainite, followed by cooling to generate some high-carbon martensite. By introducing lower bainite, the multiphase structure can improve the impact toughness of the matrix and enhance the load-bearing capacity of the bearing rings.

[0003] However, the traditional isothermal quenching process for achieving Marble multiphase heat treatment results in slow early-stage nucleation and slow late-stage transformation of bainite. In actual production, this is time-consuming, costly, and unsuitable for mass production. For example, achieving a 50% bainite content requires at least 1 hour of isothermal quenching. Furthermore, blindly increasing the isothermal quenching temperature in pursuit of a shorter incubation period and higher nucleation rate can easily lead to coarsening and coalescence of the lath microstructure, thus degrading performance. In addition, rolling, as a pre-treatment process, significantly influences the phase transformation kinetics of subsequent heat treatment processes. Therefore, the effect of deformation on multiphase heat treatment must be fully considered when developing heat treatment processes.

[0004] In summary, there is an urgent need to provide a rapid method for forming a martensitic-bainitic (Marbe) multiphase microstructure in rolled bearing steel, so as to achieve rapid formation of bainite in rolled bearing steel while achieving precise control over the phase ratio and morphology of the multiphase microstructure. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings, so as to achieve fine control of the phase ratio and morphology of the multiphase structure while rapidly forming bainite in the rolled bearing steel.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, embodiments of this application provide an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings, comprising: determining the target austenite grain size and target austenite carbon mass fraction of the rolled bearing steel according to the target of the Marbe multiphase heat treatment; determining the target austenitizing process parameters for obtaining the target austenite grain size and the target austenite carbon mass fraction according to the target rolling deformation and the initial carbon mass fraction of the rolled bearing steel; controlling the austenitizing process using the target austenitizing process parameters to obtain the target austenite; and using a staged isothermal quenching process to transform the target austenite phase into the target austenite phase. The bainite formation process is controlled as follows: In the first-stage isothermal quenching process, the first-stage isothermal quenching process parameters are determined based on the target bainite nucleation parameters, and the first-stage isothermal quenching process is controlled using these parameters; in the second-stage isothermal quenching process, the second-stage isothermal quenching process parameters are determined based on the target bainite growth parameters, and the second-stage isothermal quenching process is controlled using these parameters; in the third-stage isothermal quenching process, the third-stage isothermal quenching process parameters are determined based on the target bainite volume fraction parameters, and the third-stage isothermal quenching process is controlled using these parameters.

[0008] In one embodiment, determining the target austenite grain size and target austenite carbon content of the rolled bearing steel based on the Marbai multiphase heat treatment target includes: determining the target austenite grain size and target austenite carbon content of the rolled bearing steel based on the target bainite nucleation parameters and target bainite growth parameters during the Marbai multiphase heat treatment process; the Marbai multiphase heat treatment target includes the target bainite nucleation parameters and target bainite growth parameters.

[0009] In one embodiment, determining the target austenitizing process parameters for obtaining the target austenite grain size and the target austenite carbon content based on the target rolling deformation amount and the initial carbon content of the rolled bearing steel includes: determining the austenite grain size obtained by the rolled bearing steel at different temperatures under the target rolling deformation amount based on the relationship between the rolling deformation amount, the austenite grain size, and the austenitizing temperature, so as to determine the temperature for obtaining the target austenite grain size; determining the time for obtaining the target austenite carbon content based on the relationship between the initial carbon content of the rolled bearing steel, the austenite carbon content, and the austenitizing time; the target austenitizing process parameters include the temperature for obtaining the target austenite grain size and the time for obtaining the target austenite carbon content.

[0010] In one embodiment, determining the primary isothermal quenching process parameters based on the target bainite nucleation parameters includes: determining the primary isothermal quenching temperature at the target bainite nucleation rate based on the relationship between the initial martensitic transformation temperature, the bainite nucleation rate, and the isothermal quenching temperature; and determining the primary isothermal quenching time at the first target bainite volume fraction based on the relationship between the rolling deformation, the bainite volume fraction, and the isothermal quenching time. The target bainite nucleation parameters include the target bainite nucleation rate and the first target bainite volume fraction.

[0011] In one embodiment, the target bainite nucleation rate is >10. 16 m -2 The first target bainite volume fraction includes 10%.

[0012] In one embodiment, determining the secondary isothermal quenching process parameters based on the target bainite growth parameters includes: determining the secondary isothermal quenching temperature at the target bainite growth rate based on the relationship between rolling deformation, bainite growth rate, and isothermal quenching temperature; and determining the secondary isothermal quenching time at the target bainite bundle length based on the relationship between bainite bundle length, bainite growth rate, and isothermal quenching time. The target bainite growth parameters include the target bainite growth rate and the target bainite bundle length.

[0013] In one embodiment, the target bainite growth rate is >0.02 μm / s, and the target bainite bundle length is >5 μm.

[0014] In one embodiment, determining the three-stage isothermal quenching process parameters based on the target bainite volume fraction parameter includes: determining the three-stage isothermal quenching temperature under the target bainite volume fraction growth rate based on the relationship between rolling deformation, the bainite volume fraction growth rate, and the isothermal quenching temperature; determining the three-stage isothermal quenching time under the second target bainite volume fraction based on the relationship between rolling deformation, the difference in bainite volume fraction between the three-stage isothermal quenching process and the first-stage isothermal quenching process, and the isothermal quenching time; the target bainite volume fraction parameter includes the target bainite volume fraction growth rate and the second target bainite volume fraction.

[0015] In one embodiment, the target bainite volume fraction growth rate is >10%. -4 s -1 The second target bainite volume fraction is the ultimate target bainite volume fraction.

[0016] In one embodiment, the target austenite grain size is ≤10μm, and the target austenite carbon element mass fraction is ≤0.8%.

[0017] The beneficial effects of this application are as follows: By optimizing and controlling the austenitic grain size and carbon content of rolled bearing steel through austenitization process parameters, preparation is made for subsequent efficient Marbai multiphase heat treatment; a staged isothermal quenching process is used to achieve rapid nucleation, orderly elongation, precise quantitative control, and efficient bainitic phase transformation of rolled bearing steel, avoiding the problems of slow early nucleation and easy coarsening of bainite in the later stage. The rolling deformation of bearing steel will have a hereditary influence on the microstructure of subsequent heat treatment. In order to achieve rapid nucleation and controllable size of bainite in rolled bearing steel, refined control of the austenitic microstructure is performed to provide sufficient positions for bainite nucleation and effective driving force for bainite elongation; through bainite nucleation and growth kinetic calculations, the multi-stage isothermal quenching temperature and time are determined; the first-stage isothermal quenching shortens the incubation period and promotes rapid nucleation, preparing for subsequent heat treatment; the second-stage isothermal quenching ensures that the bainite morphology meets the requirements; and the third-stage isothermal quenching rapidly achieves the target volume fraction. This process effectively solves the problem of inhibited bainite growth in the later stage of the subsequent heat treatment of rolled bearing steel, thereby ensuring the acquisition of high-strength and high-toughness Marble multiphase microstructure while significantly reducing the multiphase heat treatment time, lowering heat treatment costs, and improving heat treatment efficiency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic flowchart illustrating an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this application embodiment;

[0020] Figure 2 A schematic flowchart illustrating an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this application embodiment;

[0021] Figure 3 A schematic flowchart illustrating an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this application embodiment.

[0022] Figure 4 A schematic flowchart illustrating an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this application embodiment;

[0023] Figure 5 This is a schematic flowchart illustrating an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings, provided in an embodiment of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] In the description of this application, it should be noted that if the terms "upper", "lower", etc. appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this application is usually placed in, it is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] Furthermore, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Additionally, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0029] Figure 1 This is a schematic flowchart illustrating an efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings, as provided in an embodiment of this application. Figure 1 As shown, the method includes:

[0030] Step 110: Determine the target austenite grain size and target austenite carbon content of the rolled bearing steel according to the Marbe multiphase heat treatment target.

[0031] Marbe multiphase heat treatment is a heat treatment process that combines martensite and bainite, aiming to optimize the microstructure and mechanical properties of materials through different heat treatment stages.

[0032] Martensite is a supersaturated solid solution of carbon in α-Fe, possessing high strength and hardness. Martensite was initially obtained in steel through a quenching process, which involves heating the steel to a certain temperature and then rapidly cooling it. The three-dimensional morphology of martensite is typically lamellar or plate-like, but it often appears as acicular structures in metallographic observation. Martensite is an important means of strengthening steel components, but it is also a hard and brittle structure, especially high-carbon lamellar martensite.

[0033] Austenite is a lamellar microstructure of steel, a solid solution of carbon and alloying elements dissolved in γ-Fe, also known as wostenite or γ-Fe. Austenite has good plasticity, low strength, some toughness, and is non-ferromagnetic. Because austenite has a face-centered cubic structure with large interfacial spaces between its octahedrons, it can accommodate more carbon. In steel processing, steel ingots, billets, and finished steel are typically heated to above 1100℃ to form austenite, followed by plastic forming processes such as forging and rolling. Austenite has poor thermal conductivity and a high coefficient of linear expansion; these properties make austenitic steel suitable for manufacturing instrument components sensitive to thermal expansion.

[0034] Bainite is a transformation product formed when austenite is supercooled to a specific temperature range; it is a mixed microstructure of ferrite and carbides. Bainite has attracted much attention due to its unique transformation mechanism and properties, with its transformation temperature range lying between the pearlite and martensite transformation temperatures. Depending on the transformation temperature, bainite can be divided into upper bainite and lower bainite. The final heat treatment state of bainitic steel is usually furnace cooling, air cooling, or mold cooling. Its microstructure is predominantly lower bainite, but lath martensite and carbon-free bainite may also appear.

[0035] The objective of the Marble multiphase heat treatment, namely the purpose of the efficient and precise Marble multiphase heat treatment method for high-carbon steel bearings provided in this application embodiment, is to provide a rapid formation method for martensite-bainite (Marble) multiphase microstructure in rolled bearing steel, so as to achieve rapid formation of bainite in rolled bearing steel while achieving fine control of the phase ratio and morphology of the multiphase microstructure; specifically, it refers to the target bainite nucleation parameters and target bainite growth parameters, which indicate the rapid nucleation and growth of target bainite.

[0036] In this embodiment of the application, in order to ensure the target of the Marbe multiphase heat treatment process (e.g., rapid nucleation and growth of target bainite), the austenite needs to meet the two conditions of fine grain size and controllable carbon element mass fraction; therefore, this step needs to determine the target austenite grain size and the target austenite carbon element mass fraction.

[0037] Specifically, step 110 above may further include the following steps:

[0038] Based on the target bainite nucleation parameters and target bainite growth parameters during the Marble multiphase heat treatment process, the target austenite grain size and target austenite carbon content of the rolled bearing steel are determined.

[0039] Among them, the targets of Marble multiphase heat treatment include target bainite nucleation parameters and target bainite growth parameters.

[0040] In this embodiment of the application, the target austenite grain size is ≤10μm and the target austenite carbon element mass fraction is ≤0.8% as determined by the Marbe multiphase heat treatment target; thus, the Marbe multiphase heat treatment target (e.g., rapid nucleation and growth of target bainite) can be guaranteed in the subsequent heat treatment process.

[0041] Step 120: Determine the target austenitizing process parameters for obtaining the target austenite grain size and the target austenite carbon content based on the target rolling deformation amount and the initial carbon content of the rolled bearing steel.

[0042] Among them, since rolling deformation has an impact on rolled bearing steel, such as promoting carbide dissolution and inhibiting grain growth, the influence of rolling deformation on rolled bearing steel needs to be considered.

[0043] The target austenitizing process parameters can be determined based on the relationship between the rolling deformation, the initial carbon mass fraction of the rolled bearing steel, and the austenitizing process parameters; specifically... Figure 2 This is a schematic flowchart illustrating the efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this embodiment of the application. Figure 2 As shown, step 120 above may further include steps 210 and 220:

[0044] Step 210: Based on the relationship between rolling deformation, austenite grain size and austenitizing temperature, determine the austenite grain size obtained by rolling bearing steel at different temperatures under the target rolling deformation, so as to determine the temperature at which the target austenite grain size is obtained.

[0045] The relationship between rolling deformation, austenite grain size and austenitizing temperature is shown in the following formula (1):

[0046]

[0047] Where D is the austenite grain size; t A T is the austenitizing time; AThe austenitizing temperature is given; A is a constant, which can be taken as 2.248 × 10⁻⁶ within the range of 800–1050 °C. 16 Q A ε is the activation free energy for austenite transformation; n is the correction coefficient for rolling deformation ε, n = 3.21 × (1 + ε); R is the ideal gas constant, which is 8.314 J / mol·K.

[0048] In practice, the austenite grain size obtained at different temperatures (keeping the quenching time the same but the temperature different) is calculated according to the above formula (1), and then the temperature T at which the target austenite grain size is obtained is obtained. A .

[0049] Step 220: Determine the time to obtain the target austenitic carbon content based on the relationship between the initial carbon content of the rolled bearing steel, the austenitic carbon content, and the austenitizing time.

[0050] The target austenitization process parameters include the temperature at which the target austenite grain size is obtained and the time at which the target austenite carbon element mass fraction is obtained.

[0051] The relationship between the initial carbon mass fraction, the austenitic carbon mass fraction, and the austenitizing time of rolled bearing steel is shown in the following formula (2):

[0052] W C,γ =0.067×(0.15-X) θ ) / X γ (2)

[0053] Among them, the carbon diffusion equilibrium law (the average carbon content C0 of GCr15 steel is 1.02%), W C,γ X represents the mass fraction of carbon in austenite; θ This represents the final carbon volume fraction in rolled bearing steel. X0 represents the initial carbon volume fraction of the rolled bearing steel, t A β is the austenitizing time, and β is the kinetic constant. c and m are both constants, ε is the rolling deformation, and Q A For the activation free energy of austenite transformation, T A X is the austenitizing temperature, R is the ideal gas constant, which is 8.314 J / mol·K; γ This represents the volume fraction of austenite.

[0054] In practice, the time t for obtaining the target austenite carbon element mass fraction can be calculated according to the above formula (2). A .

[0055] Step 130: Control the austenitizing process using the target austenitizing process parameters to obtain the target austenite.

[0056] In this step, the temperature T for obtaining the target austenite grain size, calculated in step 210 above, is used. A The time t for obtaining the target austenite carbon element mass fraction calculated in step 220. A The austenitization process of rolled bearing steel is controlled; in this way, the austenite grain size and the mass fraction of austenite carbon can be controlled. Specifically, step 210 can control the austenite grain size, and step 220 can control the mass fraction of austenite carbon.

[0057] Step 140: The process of transforming the target austenite phase into the target bainite is controlled by a graded isothermal quenching process. In the first-stage isothermal quenching process, the first-stage isothermal quenching process parameters are determined according to the target bainite nucleation parameters, and the first-stage isothermal quenching process is controlled using the first-stage isothermal quenching process parameters. In the second-stage isothermal quenching process, the second-stage isothermal quenching process parameters are determined according to the target bainite growth parameters, and the second-stage isothermal quenching process is controlled using the second-stage isothermal quenching process parameters. In the third-stage isothermal quenching process, the third-stage isothermal quenching process parameters are determined according to the target bainite volume fraction parameters, and the third-stage isothermal quenching process is controlled using the third-stage isothermal quenching process parameters.

[0058] The graded isothermal quenching process includes first-stage isothermal quenching, second-stage isothermal quenching, and third-stage isothermal quenching. During first-stage isothermal quenching, bainite rapidly nucleates; during second-stage isothermal quenching, bainite grows; and during third-stage isothermal quenching, bainite rapidly reaches the final target bainite volume fraction. Specifically... Figure 3 This is a schematic flowchart illustrating the efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this embodiment of the application. Figure 3 As shown, step 140 above may further include steps 310 and 320:

[0059] Step 310: Based on the relationship between the initial temperature of martensite transformation, the bainite nucleation rate and the isothermal quenching temperature, determine the first-level isothermal quenching temperature under the target bainite nucleation rate.

[0060] The relationship between the initial temperature of martensite transformation, the nucleation rate of bainite, and the isothermal quenching temperature is shown in the following formula (3):

[0061] N m =V m (T1-M s (3)

[0062] Where, N mThe third preset formula, also known as the nucleation rate model, is the nucleation rate formula; V0 is the trial frequency; T1 is the isothermal quenching temperature; M s This is the temperature at which the martensitic transformation begins.

[0063] In practice, by substituting the target bainite nucleation rate into the above formula (3), the first-level isothermal quenching temperature under the target bainite nucleation rate can be obtained.

[0064] Step 320: Determine the first-stage isothermal quenching time under the first target bainite volume fraction based on the relationship between rolling deformation, bainite volume fraction and isothermal quenching time.

[0065] The target bainite nucleation parameters include the target bainite nucleation rate and the first target bainite volume fraction.

[0066] The relationship between rolling deformation, bainite volume fraction and isothermal quenching time is shown in the following formula (4):

[0067]

[0068] Where t1 is the isothermal quenching time; Q * G To activate the free energy, C1 and C2 are constants; f is the volume fraction of bainite.

[0069] In practice, by substituting the volume fraction of the first target bainite into the above formula (4), the first-level isothermal quenching time under the volume fraction of the first target bainite can be obtained.

[0070] Because the bainite transformation rate is relatively fast under these conditions, the bainite bundles rapidly coarsen and merge in the later stages; therefore, it is necessary to strictly control the isothermal time to keep the bainite volume fraction at around 10% (the first target bainite volume fraction). The process is determined using a bainite phase transformation kinetic model, and given a fixed bainite volume fraction f, the formula for the isothermal quenching time t1 required for this bainite volume fraction is obtained.

[0071] The target bainite nucleation rate and the first target bainite volume fraction are determined according to the rolling bearing steel Marbai multiphase heat treatment target of the high-carbon steel bearing high-efficiency and precise Marbai multiphase heat treatment method provided in the embodiments of this application; specifically, the target bainite nucleation rate is >10. 16 m -2 The first target bainite volume fraction includes 10%; thus, bainite can be rapidly nucleated during the first-stage isothermal quenching process.

[0072] The following examples further illustrate the process of determining the secondary isothermal quenching process parameters based on the target bainite growth parameters in the above embodiments. Specifically, Figure 4This is a schematic flowchart illustrating the efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this embodiment of the application. Figure 4 As shown, step 140 above may further include steps 410 and 420:

[0073] Step 410: Determine the secondary isothermal quenching temperature at the target bainite growth rate based on the relationship between rolling deformation, bainite growth rate and isothermal quenching temperature.

[0074] The relationship between rolling deformation, bainite growth rate and isothermal quenching temperature is shown in the following formula (5):

[0075]

[0076] Among them, V i V0 is the bainite growth rate; V0 is the pre-exponential factor, which is 30 m / s; ε is the rolling deformation; Q0 * G The activation free energy; k is the Boltzmann constant, which is 1.380649 × 10⁻⁶. -23 J / K; T2 is the isothermal quenching temperature.

[0077] In practice, by substituting the target bainite growth rate into the above formula (5), the secondary isothermal quenching temperature under the target bainite growth rate can be obtained.

[0078] Step 420: Determine the secondary isothermal quenching time for the target bainite bundle length based on the relationship between the bainite bundle length, the bainite growth rate and the isothermal quenching time.

[0079] The target bainite growth parameters include the target bainite growth rate and the target bainite bundle length.

[0080] The relationship between bainite bundle length, bainite growth rate and isothermal quenching time is shown in the following formula (6):

[0081] l=R0+V i t2 (6)

[0082] Where l is the length of the bainite bundle; R0 is the nucleation radius; and t2 is the isothermal quenching time.

[0083] In practice, by substituting the target bainite bundle length into the above formula (6), the secondary isothermal quenching time under the target bainite bundle length can be obtained.

[0084] The target bainite growth rate and target bainite bundle length are determined according to the target of the high-carbon steel bearing multiphase heat treatment method provided in the embodiments of this application for the rolling bearing steel multiphase heat treatment; specifically, the target bainite growth rate is >0.02μm / s and the target bainite bundle length is >5μm; thus, bainite can grow rapidly during the secondary isothermal quenching process.

[0085] The following example further illustrates the process of determining the three-stage isothermal quenching process parameters based on the target bainite volume fraction parameter in the above embodiments. Specifically, Figure 5 This is a schematic flowchart illustrating the efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this embodiment of the application. Figure 5 As shown, step 140 above may further include steps 510 and 520:

[0086] Step 510: Based on the relationship between rolling deformation, bainite volume fraction growth rate and isothermal quenching temperature, determine the third-stage isothermal quenching temperature under the target bainite volume fraction growth rate.

[0087] The relationship between rolling deformation, bainite volume fraction growth rate and isothermal quenching temperature is shown in the following formula (7):

[0088]

[0089] in, C1 and C2 are constants; ε is the rolling deformation; Q is the growth rate of bainite volume fraction (second target bainite volume fraction growth rate); ε is the growth rate of bainite volume fraction (second target bainite volume fraction growth rate); ... ε is the growth rate of bainite volume fraction * G The activation free energy is ; R is the ideal gas constant, which is 8.314 J / mol·K; T3 is the isothermal quenching temperature (third-stage isothermal quenching temperature).

[0090] In practice, by substituting the target bainite volume fraction growth rate into the above formula (7), the third-level isothermal quenching temperature under the target bainite volume fraction growth rate can be obtained.

[0091] Step 520: Based on the relationship between the rolling deformation, the difference in bainite volume fraction between the three-stage isothermal quenching process and the first-stage isothermal quenching process, and the isothermal quenching time, determine the three-stage isothermal quenching time under the second target bainite volume fraction.

[0092] The target bainite volume fraction parameter includes the target bainite volume fraction growth rate and the second target bainite volume fraction.

[0093] The relationship between rolling deformation, the difference in bainite volume fraction between the three-stage isothermal quenching process and the one-stage isothermal quenching process, and isothermal quenching time is shown in the following formula (8):

[0094]

[0095] Where t3 is the third-stage isothermal quenching time; Δf is the difference in bainite volume fraction between the third-stage isothermal quenching process and the first-stage isothermal quenching process.

[0096] In practice, the difference between the volume fraction of the second target bainite and the volume fraction of the first target bainite is substituted into the above formula (8) to obtain the three-stage isothermal quenching time under the volume fraction of the second target bainite.

[0097] The second target bainite volume fraction is the same as the ultimate target bainite volume fraction mentioned above.

[0098] The target bainite volume fraction growth rate and the second target bainite volume fraction are determined according to the rolling bearing steel Marbai multiphase heat treatment target of the high-carbon steel bearing high-efficiency and precise Marbai multiphase heat treatment method provided in the embodiments of this application; the target bainite volume fraction growth rate is >10%. -4 s -1 The second target bainite volume fraction can be determined according to the actual purpose; in this way, the bainite can quickly reach the ultimate target bainite volume fraction (second target bainite volume fraction) during the three-stage isothermal quenching process.

[0099] The efficient and precise Marbe multiphase heat treatment method for high-carbon steel bearings provided in this application involves, firstly, determining the target austenite grain size and target austenite carbon content in the rolled bearing steel based on the desired Marbe multiphase heat treatment objective; secondly, determining the target austenitizing process parameters to obtain the target austenite grain size and target austenite carbon content based on the target rolling deformation and the initial carbon content of the rolled bearing steel; thirdly, controlling the austenitizing process using the target austenitizing process parameters to obtain the target austenite; and finally, using a staged isothermal quenching process to transform the target austenite phase into... The process of developing the target bainite is controlled. In the first-stage isothermal quenching, the process parameters are determined based on the target bainite nucleation parameters, and these parameters are used to control the first-stage isothermal quenching process. In the second-stage isothermal quenching, the process parameters are determined based on the target bainite growth parameters, and these parameters are used to control the second-stage isothermal quenching process. In the third-stage isothermal quenching, the process parameters are determined based on the target bainite volume fraction parameters, and these parameters are used to control the third-stage isothermal quenching process. In this way, by optimizing the austenitization process parameters, the austenite grain size and austenite carbon mass fraction in the rolled bearing steel are controlled, preparing for subsequent efficient Marble multiphase heat treatment. The staged isothermal quenching process achieves rapid nucleation, orderly elongation, precise quantitative control, and efficient bainite phase transformation in the rolled bearing steel, avoiding the problems of slow early-stage bainite nucleation and easy coarsening in the later stages. The rolling deformation of bearing steel has a genetic impact on the microstructure of subsequent heat treatment. To achieve rapid nucleation and controllable size of bainite in rolled bearing steel, refined control of the austenite microstructure is implemented to provide sufficient nucleation sites and effective driving force for bainite elongation. Through bainite nucleation and growth kinetic calculations, multi-stage isothermal quenching temperatures and times were determined. The first stage of isothermal quenching shortens the incubation period and promotes rapid nucleation, preparing for subsequent heat treatment. The second stage of isothermal quenching ensures the bainite morphology meets requirements. The third stage of isothermal quenching rapidly achieves the target volume fraction. This process effectively solves the problem of inhibited late-stage bainite growth during the subsequent heat treatment of rolled bearing steel, thereby significantly reducing the multiphase heat treatment time, lowering heat treatment costs, and improving heat treatment efficiency while ensuring the acquisition of a high-strength and high-toughness marble multiphase microstructure.

[0100] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for efficient and precise Marbe multiphase heat treatment of high-carbon steel bearings, characterized in that, include: Based on the Marbe multiphase heat treatment target, determine the target austenite grain size and target austenite carbon content of the rolled bearing steel; Based on the target rolling deformation amount and the initial carbon element mass fraction of the rolled bearing steel, the target austenitizing process parameters for obtaining the target austenite grain size and the target austenite carbon element mass fraction are determined. The austenitizing process is controlled using the target austenitizing process parameters to obtain the target austenitizing material; The process of transforming the target austenite phase into the target bainite is controlled by a graded isothermal quenching process. In the first-stage isothermal quenching process, the first-stage isothermal quenching process parameters are determined according to the target bainite nucleation parameters, and the first-stage isothermal quenching process is controlled by the first-stage isothermal quenching process parameters. In the secondary isothermal quenching process, the secondary isothermal quenching process parameters are determined according to the target bainite growth parameters, and the secondary isothermal quenching process is controlled using the secondary isothermal quenching process parameters; in the tertiary isothermal quenching process, the tertiary isothermal quenching process parameters are determined according to the target bainite volume fraction parameters, and the tertiary isothermal quenching process is controlled using the tertiary isothermal quenching process parameters.

2. The method according to claim 1, characterized in that, The determination of the target austenite grain size and target austenite carbon content in rolled bearing steel based on the Marbe multiphase heat treatment target includes: Based on the target bainite nucleation parameters and target bainite growth parameters during the Marble multiphase heat treatment process, the target austenite grain size and the target austenite carbon content of the rolled bearing steel are determined; the target of the Marble multiphase heat treatment includes the target bainite nucleation parameters and the target bainite growth parameters.

3. The method according to claim 1, characterized in that, The process of determining the target austenitizing parameters for obtaining the target austenite grain size and the target austenite carbon content based on the target rolling deformation and the initial carbon content of the rolled bearing steel includes: Based on the relationship between rolling deformation, austenite grain size and austenitizing temperature, the austenite grain size of the rolled bearing steel at different temperatures under the target rolling deformation is determined, so as to determine the temperature at which the target austenite grain size is obtained. Based on the relationship between the initial carbon element mass fraction, the austenitic carbon element mass fraction, and the austenitizing time of the rolled bearing steel, the time for obtaining the target austenitic carbon element mass fraction is determined; the target austenitizing process parameters include the temperature for obtaining the target austenitic grain size and the time for obtaining the target austenitic carbon element mass fraction.

4. The method according to claim 1, characterized in that, The determination of primary isothermal quenching process parameters based on the target bainite nucleation parameters includes: Based on the relationship between the initial temperature of martensite transformation, the nucleation rate of bainite and the isothermal quenching temperature, the first-level isothermal quenching temperature under the target bainite nucleation rate is determined. Based on the relationship between rolling deformation, bainite volume fraction, and isothermal quenching time, the first-stage isothermal quenching time under the first target bainite volume fraction is determined; the target bainite nucleation parameters include the target bainite nucleation rate and the first target bainite volume fraction.

5. The method according to claim 4, characterized in that, The target bainite nucleation rate is >10. 16 m -2 The first target bainite volume fraction includes 10%.

6. The method according to claim 1, characterized in that, The determination of the secondary isothermal quenching process parameters based on the target bainite growth parameters includes: Based on the relationship between rolling deformation, bainite growth rate and isothermal quenching temperature, the secondary isothermal quenching temperature at the target bainite growth rate is determined. Based on the relationship between bainite bundle length, bainite growth rate and isothermal quenching time, the secondary isothermal quenching time for the target bainite bundle length is determined; the target bainite growth parameters include the target bainite growth rate and the target bainite bundle length.

7. The method according to claim 6, characterized in that, The target bainite growth rate is >0.02 μm / s, and the target bainite bundle length is >5 μm.

8. The method according to claim 1, characterized in that, The determination of the three-stage isothermal quenching process parameters based on the target bainite volume fraction parameter includes: Based on the relationship between rolling deformation, bainite volume fraction growth rate and isothermal quenching temperature, the third-stage isothermal quenching temperature under the target bainite volume fraction growth rate is determined. Based on the relationship between the rolling deformation, the difference in bainite volume fraction between the three-stage isothermal quenching process and the first-stage isothermal quenching process, and the isothermal quenching time, the three-stage isothermal quenching time under the second target bainite volume fraction is determined; the target bainite volume fraction parameter includes the target bainite volume fraction growth rate and the second target bainite volume fraction.

9. The method according to claim 8, characterized in that, The target bainite volume fraction growth rate is >10%. -4 s -1 .

10. The method according to claim 1, characterized in that, The target austenite grain size is ≤10μm, and the target austenite carbon element mass fraction is ≤0.8%.

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