JP7625981B2 - Manufacturing method of rolling bearing - Google Patents

Description

The present invention relates to a method for manufacturing rolling bearings.

It is known that when rolling bearings are subjected to excessive static loads during fitting or while stationary, Hertzian contact occurs between the outer and inner raceways and the rolling elements, resulting in permanent deformation (indentations) at these contact points. If such indentations are present on the raceways, they affect the acoustic and vibration characteristics when the ball bearings are in use. For example, in machine tools used under high-temperature conditions and high-speed rotation, even minute indentations of about 1 μm can cause serious problems in terms of abnormal noise and vibration. For this reason, when designing rolling bearings, the basic static load rating is determined by the contact stress, and JIS B 1519 stipulates that the contact stress for radial ball bearings, excluding thrust ball bearings and self-aligning ball bearings, is 4.2 GPa.

In addition, with the background of improved performance such as fuel efficiency in automobiles, there is an increasing demand for smaller bearings, and plastic deformation resistance that can withstand excessive static loads is required. In order to improve the plastic deformation resistance of bearings, the balance between the material hardness of the outer and inner rings of the bearing and the amount of retained austenite is important. For this reason, efforts have been made to improve indentation resistance by improving the hardness of the outer and inner rings and reducing the soft retained austenite. For example, in Patent Document 1, the indentation resistance of bearings is improved by reducing the retained austenite through sub-zero treatment and high-temperature tempering. In addition, in Patent Document 2, indentation resistance is improved by applying carbonitriding treatment to high carbon chromium steel.

Furthermore, in operating environments such as the high temperatures and high speeds of machine tools, the formation of an oil film may be insufficient, causing metallic contact between the outer and inner rings and the rolling elements, which may result in seizure. For this reason, in addition to the impression resistance of the material used in the bearing, seizure resistance must also be considered. For example, in Patent Document 3, by adjusting the composition, high-temperature tempering after carbonitriding does not reduce functions such as hardness, ensuring seizure resistance even under poor lubrication conditions.

JP 2000-274440 A JP 2015-200351 A Patent No. 3873741

However, there is a strong demand for further improvement in indentation resistance, and there is a limit to how much further improvement in indentation resistance can be achieved by heat treatment and composition adjustments alone as described above. At the same time, there is also a demand to ensure sufficient seizure resistance.

The present invention was made with the above-mentioned problems in mind, and aims to provide a manufacturing method for a rolling bearing that has excellent seizure resistance and improves indentation resistance.

Here, the formation of the indentation is a plastic deformation of the raceway and can be considered a simple material yield phenomenon, and there is a technique called work hardening. The inventors have discovered that in order to improve indentation resistance while also achieving excellent seizure resistance, it is effective to use a steel material with a specified chemical composition that is a material with excellent seizure resistance as the material that constitutes the raceway, and to subject the steel material to a specific heat treatment, i.e., carbonitriding or carburizing, and then to subject the raceway surface of the raceway to work hardening treatment by machining.

The present invention is based on this knowledge, and provides a method for manufacturing a rolling bearing as shown below in (1) in order to solve the above problems.

A method for manufacturing a rolling bearing in which a plurality of rolling elements are held between races having raceways, the method comprising the steps of:
a material constituting the raceway contains, by mass%, C: 0.2 to 1.2%, Si: 0.5 to 1.5%, Mn: 0.1 to 1.5%, Cr: 2.5% or less, Mo: 1.5% or less (including 0%), with the balance being Fe and unavoidable impurities;
A method for manufacturing a rolling bearing, comprising the steps of: subjecting the material to carbonitriding or carburizing treatment; tempering the material at 250°C or higher; and then subjecting the raceway surfaces to work-hardening treatment by machining.

Furthermore, preferred embodiments of the present invention relating to the manufacturing method of rolling bearings relate to the following (2) to (5).

(2) A method for producing a rolling bearing according to (1) above, characterized in that Si carbonitrides or Si carbides are dispersed and precipitated in the surface layer of the raceway surface by the carbonitriding treatment or the carburizing treatment.
(3) The method for producing a rolling bearing according to (2) above, wherein the Si carbonitride or the Si carbide contains at least one of Si--Mn, Si--Mo, and Si--Cr.
(4) A method for producing a rolling bearing according to any one of (1) to (3) above, characterized in that the machining is burnishing.
(5) a first curve showing a yield shear stress in a depth direction of the raceway surface before the raceway surface is machined; and
a second curve showing a static shear stress in a depth direction of the raceway surface in a state in which the raceway surface has been machined;
a third curve showing a static shear stress in the depth direction of the raceway surface in a state in which the rolling elements are in contact with the raceway surface and a static load is applied; and
The area enclosed by the first curve, the second curve, and the third curve is below the area A;
When the area enclosed by the area above the first curve and below the third curve is defined as area S,
The method for manufacturing a rolling bearing according to any one of (1) to (4) above, characterized in that the machining is carried out under machining conditions that satisfy the relationship: area A < area S.

The manufacturing method of the present invention can suppress the formation of minute indentations of about 1 μm on the raceway surface in bearings, such as machine tool spindles, where excessive static loads are applied to the raceways and indentations are likely to occur, and makes it possible to manufacture rolling bearings that are less susceptible to seizure even under high-speed rotation, i.e., have excellent seizure resistance and improved indentation resistance.

FIG. 1 is a partially cutaway perspective view showing a radial ball bearing, which is an example of a rolling bearing. FIG. 2 is a schematic diagram for explaining a method for calculating the area S. In FIG. FIG. 3 is a schematic diagram for explaining a method of calculating the area A. In FIG. FIG. 4 is a graph showing the limit PV value until seizure occurs for the steel material (bearing material) used in the examples and SUJ2 steel (standard bearing steel). FIG. 5 is a graph showing the temper softening resistance performance of the steel material (bearing material) used in the examples and SUJ2 steel (standard bearing steel). FIG. 6 is a graph showing the relationship between the maximum surface pressure and the indentation depth in Examples 1 to 4 and the Comparative Example. FIG. 7 is a graph showing the relationship between the maximum surface pressure and the deformation resistance improvement index R _D in Examples 1 to 4 and the comparative example.

The following is a detailed description of an embodiment of the present invention. However, the present invention is not limited to the following embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

In the present invention, there is no limit to the type or configuration of the rolling bearing that can be obtained, and for example, a radial ball bearing as shown in FIG. 1 can be shown. As shown in the figure, the radial ball bearing 1 comprises an outer ring 3 having an outer ring raceway surface 2 on its inner peripheral surface, an inner ring 5 having an inner ring raceway surface 4 on its outer peripheral surface, and a number of balls 6, each of which is a rolling element, disposed between the outer ring raceway surface 2 and the inner ring raceway surface 4. Each of these balls 6 is held by a cage 7 so as to be freely rollable, with the balls 6 evenly spaced apart in the circumferential direction.

In the manufacturing method of the rolling bearing according to this embodiment, first, a steel material having a predetermined chemical composition, which will be described later, is subjected to a carbonitriding or carburizing process as the material for the raceways (outer ring 3 and inner ring 5) to disperse and precipitate Si-containing carbonitrides (hereinafter referred to as "Si carbonitrides") or Si-containing carbides (hereinafter referred to as "Si carbides") in the surface layer of the raceway surface. Si carbonitrides and Si carbides have a self-lubricating effect, and significantly improve seizure resistance and wear resistance without compromising rolling life. This is because they exhibit the same effect as the self-lubricating action of molybdenum disulfide and other materials, and can prevent metal contact and improve seizure life and wear life.

The content of Si carbonitride or Si carbide in the surface layer is preferably 1 to 30 mass% in order to fully exert the self-lubricating effect. If the content is less than 1 mass%, the lubricating effect is insufficient, while if it exceeds 30 mass%, not only will the lubricating effect saturate, but it may also cause a decrease in toughness and shorten the rolling life.

The Si carbonitrides and Si carbides in the surface layer are, for example, Si-Mn, Si-Mo, or Si-Cr, and it is preferable that the surface layer contains at least one of these.

Furthermore, if the size (circle equivalent diameter) of the Si carbonitrides and Si carbides in the surface layer exceeds 10 μm, stress concentration increases, which may cause a decrease in rolling life. The practical lower limit of the size of the Si carbonitrides and Si carbides in the surface layer is 0.5 μm.

The carbonitriding and carburizing treatments can be carried out according to conventional methods, and the heat treatment temperature and time can be adjusted to precipitate the appropriate amounts of Si carbonitrides and Si carbides described above. The heat treatment conditions can be varied, for example, from 850 to 950°C and the time from 1 to 24 hours.

The chemical composition of other elements in the steel material that makes up the raceway rings should preferably be within the numerical ranges shown below.

[C: 0.2 to 1.2% by mass]
To obtain the cleanliness required for a rolling bearing, C (carbon) must be 0.2 mass% or more. If C exceeds 1.2 mass%, the residual austenite increases and the bearing It is preferable that the C content is 0.2 to 1.2 mass %. In order to improve the strength, prevent excessive retained austenite, and prevent the formation of eutectic carbides, the C content is more preferably 0.35 to 1.1 mass %.

[Si: 0.5 to 1.5% by mass]
Silicon (Si) is essential for forming silicon carbonitrides and silicon carbides, which are effective against seizure and friction wear. The silicon concentration required for deoxidation during steelmaking is 0.15 to 0. At 35 mass%, it is difficult to improve the seizure resistance and wear resistance, and it is necessary to add 0.5 mass% or more. However, if the amount added is too large, Si carbonitrides and Si The Si content is preferably 1.5 mass % or less because the anti-seizure and anti-wear effects of the carbide are reduced.

[Mn: 0.1 to 1.5% by mass]
Mn (manganese), like Si, is an element necessary for deoxidation during steelmaking, and is added at 0.1 mass% or more. Mn also improves hardenability and improves strength and tumble resistance after heat treatment. It also contributes to improving the dynamic fatigue life. However, if the amount of Mn added is too large, it generates residual austenite that is harmful to dimensional stability and deteriorates workability. Therefore, the Mn content is set at 1.5 mass %. % or less.

[Cr: 2.5% by mass or less]
Cr (chromium) improves hardenability and contributes to improving strength after heat treatment and rolling fatigue strength. However, if added in large amounts, it can reduce workability and cause the formation of eutectic carbides. Therefore, the Cr content is preferably 2.5 mass % or less.

[Mo: 1.5 mass% or less (including 0 mass%)]
Mo (molybdenum) is selectively added because it enhances hardenability and contributes to improving the strength and rolling fatigue life after heat treatment, but if a large amount is carbonized, the material cost increases and the workability decreases, so the Mo content is preferably 1.5 mass% or less. Note that since the Mo content is selectively added, the case where the Mo content is 0 mass% is also included.

[Balance: Fe and unavoidable impurities]
The remainder of the steel material constituting the raceway, excluding the above chemical components, is Fe (iron) and unavoidable impurities, such as S (sulfur), P (phosphorus), O (oxygen), Cu (copper), Ti (titanium), etc.

Next, in the manufacturing method of the rolling bearing according to this embodiment, after the above-mentioned carburizing or carbonitriding treatment, tempering at 250°C or higher is required. The tempering temperature is preferably 270°C or higher, and more preferably 290°C or higher. In addition, the upper limit of the tempering temperature is preferably 350°C or lower, taking into consideration the maintenance of bearing function and processing efficiency. It is particularly preferable that the temperature is close to 300°C, and in terms of a numerical range, 290 to 310°C.

When the bearing steel used in rolling bearings is carbonitrided, the structure of the surface layer (surface portion) of the raceway becomes a composite structure with a strong structure called martensite and a soft structure called retained austenite. The specified tempering is then performed to stabilize the composite structure. Note that by performing the specified heat treatment, i.e., the carburizing or carbonitriding treatment, followed by tempering at 250°C or higher, the surface layer of the raceway (depth of about 100 μm) will have a hardness of approximately HV700 and the amount of retained austenite will be 5% or less.

The bearing steel targeted in this invention (i.e., a steel material containing, by mass%, C: 0.2-1.2%, Si: 0.5-1.5%, Mn: 0.1-1.5%, Cr: 2.5% or less, Mo: 1.5% or less (including 0%), with the remainder being Fe and unavoidable impurities) has a much higher temper softening resistance than the high carbon chromium bearing steel SUJ2 of JIS G 4805 (hereinafter referred to as "SUJ2 steel"), and is characterized in that the hardness does not decrease significantly even when tempered. In other words, by subjecting the steel material to carbonitriding or carburizing treatment and then subjecting it to a specified high-temperature tempering, it is possible to impart excellent indentation resistance.

Furthermore, in the manufacturing method of the rolling bearing according to this embodiment, after the above-mentioned specified tempering, it is necessary to perform a work hardening treatment by machining on the raceway surface of the raceway ring. When performing machining, it is assumed that the greater and deeper the static shear stress distribution given by the processing load, the higher the resistance to plastic deformation. Therefore, it is preferable to obtain high resistance to plastic deformation by performing heat treatment and machining under appropriate conditions for the material used.

There is no particular restriction on the type of machining method, but vanishing and shot peening are preferred. Vanishing is a machining method in which a device with a spherical tip and high hardness parts, which is a machining jig, is pressed against the outer ring raceway surface 2 and the inner ring raceway surface 4, and the outer ring 3 and the inner ring 5 are rotated around their own axis to apply compressive stress to the outer ring raceway surface 2 and the inner ring raceway surface 4. Shot peening is a machining method in which high-hardness, approximately spherical projection material is sprayed onto the outer ring raceway surface 2 and the inner ring raceway surface 4. By adjusting the processing conditions such as the size, material, and spray speed of the approximately spherical projection material, it is possible to adjust the quality to the same as that of vanishing. Note that vanishing is preferably used as a machining process because it suppresses the deterioration of surface properties like shot peening and can suppress the amount of machining during finishing processing that is performed as necessary in a later process.

The work hardening process introduces a static shear stress to the outer ring raceway surface 2 and the inner ring raceway surface 4 that exceeds the yield shear stress of the material forming the outer ring 3 and the inner ring 5. The processing conditions can be determined, for example, as follows.

Figure 2 shows "curve a" which indicates the yield shear stress of the steel material (the material forming the rolling bearing) in the depth direction of the raceway surface, and "curve b" which indicates the static shear stress in the depth direction of the raceway surface that occurs inside the raceway ring when a certain maximum surface pressure (static load) is applied. As shown in the figure, there is an area (hatched area in the figure) where the static shear stress shown by curve b exceeds the yield shear stress of the material forming the rolling bearing shown by curve a, and the amount of plastic deformation of the raceway surface can be estimated from the size of this "area S". It can be said that the smaller this area S is, the more difficult it is to plastically deform and the less likely it is to leave an indentation on the raceway surface.

Similarly, when the raceway surface is subjected to work hardening treatment, the processing tool (a part with a spherical tip in the case of burnishing, or a roughly spherical projectile in the case of shot peening) comes into contact with the raceway surface, so this can be considered to be Hertzian contact. Also, it can be considered that a static shear stress exceeding the yield shear stress of the material forming the rolling bearing is introduced before the static load is applied.

Figure 3 shows "curve c" overlaid on Figure 2, which indicates the static shear stress generated inside the raceway when the tip of the machining jig comes into Hertz contact. It is believed that if the "area A" of the area surrounded by lines a, b, and c (the hatched portion in the figure) is reduced, the resistance to indentations will improve. In other words, in order to improve the resistance to indentations of the bearing raceway by machining, it is necessary that "area A < area S." If "area A = area S," the strengthening by the burnishing process is insufficient and does not contribute to improving the resistance to indentations. It is preferable to machine with the maximum contact pressure at which line c, which contributes to the reduction of area S, is applied inside the raceway.

Lines a, b, and c can be calculated as follows:

The static shear stress τ _st generated inside the raceway is expressed as follows at the contact point between the raceway and the rolling element:
If the normal stress σ _x (unit: MPa) generated in the tangential direction of the rolling element is taken as the normal stress σ _z (unit: MPa) generated in the normal direction, then it can be expressed by the following formula (1).

In the case of point contact, the normal stresses σ _x and σ _z can be calculated using, for example, Hanson's elastic theory solution (Hanson, M.T. and Johnson, T., "The Elastic Field for Spherical Hertzian Contact of Isotropic Bodies Revisited: Some Alternative Expressions", Transactions of the ASME, Journal of Tribology, Vol. 115 (1993), pp. 327-332). The maximum contact pressure q _max of the Hertzian contact, the contact radius a,
Using the Poisson's ratio ν, σ _x and σ _z are expressed by the following equations (2) to (7).

Here, x = rcos θ (r > 0), and θ = 0 when x > 0, and θ = π when x < 0. The maximum contact surface pressure q _max and the contact surface radius a of the Hertz contact can be calculated with reference to, for example, "Introduction to Ball Bearing Design Calculations" (Okamoto Junzo, 2011).
In the case of line contact, the calculation can be performed using, for example, Smith's elastic theory solution (Smith, J. O., Liu, C. K. and Ill U., "Stress Due to Tangential and Normal Loads on an Elastic Solid With Application to Some Contact Stress Problems", Transaction of the ASME, Journal of Applied Mechanics, Vol. 20 (1953), pp. 157-166).

Furthermore, the yield shear stress τ _y (unit: MPa) of the material forming the rolling bearing is expressed by the following formula (8), where 0.2% proof stress is σ _0.2 and the Vickers hardness of the race is HV.

Then, by calculating each line using the above formula and integrating the difference between line a, line b, and curve c at the same depth from the surface in the depth direction from the surface, the area A can be found.

Also, for ease of calculation, it is possible to perform an approximation using the quadrature method.
That is, the contact point between the raceway and the rolling element is used as a reference to divide the normal direction of the rolling element into multiple small sections ΔZ, and the areas of these small sections are added together. For more accurate calculations, it is desirable to make the small section ΔZ smaller, but 0.01 mm is appropriate. Even if it is made smaller than this, the difference in the calculated area A is negligibly small.

After the above work hardening process, finishing is performed according to the usual method, and the balls 6 and cage 7 are installed to obtain a rolling bearing.

The effects of the present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

1. Manufacturing of rolling bearings
(Examples 1 to 4)
The inner and outer rings, which are the bearing raceways, were made of steel with a chemical composition, in mass%, of C: 0.3-0.4%, Si: 0.9-1.1%, Mn: 0.6-0.8%, Cr: 1.5%, and Mo: 0.9-1.1%, and were subjected to carbonitriding by heat treatment at 890°C for 12 hours.
After the treatment, 2 to 5% by area of silicon carbonitride was precipitated in the vicinity of a position 100 μm deep from the raceway surface (the above-mentioned area percentage is the average value measured in five fields in the vicinity of a position 100 μm deep from the raceway surface using EDS analysis).
After the carbonitriding treatment, high-temperature tempering at 300°C was carried out.

Here, FIG. 4 is a graph showing the limit PV value until seizure occurs for the steel material used in the example (shown as "bearing material in question" in the figure) and SUJ2 steel (shown as "standard bearing steel" in the figure). Also, FIG. 5 is a graph showing the temper softening resistance performance of the steel material (bearing material in question) and SUJ2 steel (standard bearing steel) used in the example. As shown in FIG. 4, the "bearing material in question" has a PV value, which is a guideline for the occurrence of surface damage such as seizure and wear, that is about 1.5 times higher than that of the "standard bearing steel," and is excellent in seizure resistance. Also, as shown in FIG. 5, it is seen that the material has excellent softening resistance (temper softening resistance) when held at high temperatures. Note that the "bearing material in question" in the results shown in FIGS. 4 and 5 was subjected to carbonitriding treatment under heat treatment conditions of 890°C x 12 hours, and then to high-temperature tempering at 300°C.

Then, after high-temperature tempering, the bearing raceways were subjected to work-hardening treatment and finish machining. Burnishing was used as the machining process for the work-hardening treatment.

Regarding the burnishing conditions, the tip shape of the burnishing tool was φ6 mm, the peripheral speed was 150 m/min, and the tool feed speed was 0.1 mm/rev in Examples 1 and 2. In Examples 3 and 4, the tip shape of the burnishing tool was φ10 mm, and other parameters were the same as in Examples 1 and 2. The processing load was 6.2 GPa in Example 1, 6.7 GPa in Example 2, 5.5 GPa in Example 3, and 5.7 GPa in Example 4.
The burnishing conditions are those that satisfy the above-mentioned "area A < area S", and the maximum contact pressure that causes the line c that contributes to the reduction in area S to be applied to the inside of the raceway is adopted as the processing condition.

Comparative Example
The inner and outer rings were made of the same steel as in Examples 1 to 4, and were subjected to only the same heat treatment as described above, but were not subjected to burnishing, and were subjected to finish processing.

<2. Indentation test>
In order to verify the indentation resistance of the rolling bearings according to Examples 1 to 4 and Comparative Example, an indentation test was carried out using a tension and compression tester manufactured by Instron Japan. As the test conditions for indentation formation, a silicon nitride ball having a diameter of 12 mm was pressed against the races of Examples 1 to 4 and Comparative Example at a strain rate of 0.2 mm/min. After reaching a predetermined maximum surface pressure, the bearing was held for 30 seconds to form a clear indentation shape. The maximum surface pressure during indentation formation was 5.00 GPa, 5.38 GPa, and 5.75 GPa. The depth of the formed indentation was then measured using a three-dimensional surface texture measuring device, Talysurf, manufactured by Taylor Hobson.

The results are shown in Table 1 and Figure 6. These results confirm that Examples 1 to 4 all have shallower indentation depths than the comparative examples. Furthermore, it was confirmed that, among the Examples, Example 4 had the highest allowable maximum surface pressure and the shallowest indentation depth. Note that each plot in Figure 6 is an actual measurement, and each curve is an approximation curve based on that plot. Furthermore, the indentation depths in Table 1 are the indentation depths at maximum surface pressures of 5.00 GPa, 5.38 GPa, and 5.75 GPa on the approximation curve in Figure 6.

Next, the above-mentioned "area A" (see FIG. 3) was calculated for each of Examples 1 to 4. For the Comparative Example, since there is no line c associated with the burnishing process shown in FIG. 3, the "area S" shown in FIG. 2 was calculated. Then, the difference was calculated by subtracting each area A from the area S when forming an indentation under three conditions of maximum surface pressures of 5.00 GPa, 5.38 GPa, and 5.75 GPa, and the difference was divided by the area S of the Comparative Example to calculate the "deformation resistance improvement index R _D ." Table 2 shows these calculation results.

7 shows the relationship between each maximum surface pressure and the deformation resistance improvement index R _D in Examples 1 to 4 and the comparative example. The deformation resistance improvement index R _D indicates that the depth of the indentation formed by the burnishing process decreases as the value approaches 1. In other words, it can be said that the closer the value of the deformation resistance improvement index R _D is to 1, the more excellent the plastic deformation resistance ability is.

Also, the performance improvement by the burnishing process can be confirmed in the range of 0<R _D < 1. It is to be noted that, from the test results, it was confirmed that all of Examples 1 to 4 have a deformation resistance improvement index R _D of more than 0. Moreover, it can be said that Example 4, which has the highest deformation resistance improvement index R _D under any maximum surface pressure, is the most suitable.

1 Radial ball bearing 2 Outer ring raceway 3 Outer ring 4 Inner ring raceway 5 Inner ring 6 Balls 7 Cage

Claims (4)

A method for manufacturing a rolling bearing in which a plurality of rolling elements are held between races having raceways, the method comprising the steps of:
a material constituting the raceway contains, by mass%, C: 0.2 to 1.2%, Si: 0.5 to 1.5%, Mn: 0.1 to 1.5%, Cr: 2.5% or less, Mo: 1.5% or less (including 0%), with the balance being Fe and unavoidable impurities;
a step of subjecting the material to a carbonitriding treatment or a carburizing treatment, subjecting the material to a tempering treatment at 250°C or more, and then subjecting the raceway surface to a work hardening treatment by machining ;
a first curve showing a yield shear stress in a depth direction of the raceway surface before the raceway surface is machined;
a second curve showing a static shear stress in a depth direction of the raceway surface in a state in which the raceway surface has been machined;
a third curve showing a static shear stress in the depth direction of the raceway surface in a state in which the rolling elements are in contact with the raceway surface and a static load is applied; and
The area enclosed by the first curve, the second curve, and the third curve is below the area A;
When the area enclosed by the area above the first curve and below the third curve is defined as area S,
A method for manufacturing a rolling bearing, characterized in that the machining is carried out under machining conditions that satisfy the relationship: area A < area S. The method for manufacturing a rolling bearing according to claim 1, characterized in that the carbonitriding or carburizing treatment causes Si carbonitrides or Si carbides to be dispersed and precipitated on the surface layer of the raceway surface. The method for manufacturing a rolling bearing according to claim 2, characterized in that the Si carbonitride or the Si carbide contains at least one of Si-Mn, Si-Mo, and Si-Cr. The method for manufacturing a rolling bearing according to any one of claims 1 to 3, characterized in that the machining is a burnishing process.

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