JP3133503U - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost rolling bearing having excellent silence and corrosion resistance and life resistance.
A plurality of rolling elements (3) are provided between an inner ring (2) and an outer ring (1). At least one of the inner ring 2 and the outer ring 1 is made of martensitic stainless steel, the major axis of the eutectic carbide contained in the stainless steel is 30 μm or less, and the average value of the equivalent circle diameter of the eutectic carbide is 0.3 to 1. 6 μm, the average area of the eutectic carbide is 0.1 to ² μm ² , the area ratio of the eutectic carbide is 2 to 7%, and the form of the eutectic carbide is 98% or more of Cr ₂₃ C ₆ The hardness of stainless steel is HRC58-62, and the amount of retained austenite in the stainless steel is 6% by volume or less.
[Selection] Figure 1

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing suitable for a rotating part of a precision device such as a VTR or a computer peripheral device.

  Conventionally used bearing steel is as described below.

  Rolling bearings such as ball bearings and roller bearings have a contact surface pressure of 1000 to 1300 MPa, and in some cases 3000 to 4000 MPa. Steel is used. The high carbon chromium bearing steel has 1.1% C-1 to 1.5% Cr as a main component, and has a change in hardenability depending on the addition amount of Mn and Mo. This steel type is quenched from a temperature of 1050 to 1120 K, tempered at 420 to 470 K, and used as a structure in which 7 to 8% of spherical cementite is dispersed in martensite. The hardness after tempering is Since HRC58-64 is high, a clean steel with less ground and non-metallic inclusions is desired. At present, it is almost manufactured using carbon deoxidation by vacuum degassing, and if necessary, electroslag remelting Materials that reduce non-metallic inclusions and make them finer are used in combination with special melting methods such as vacuum arc remelting.

  Moreover, since the carburized bearing is made by carburizing the case-hardened steel, it has a high surface hardness and a flexible core, and is particularly suitable for applications that receive impact loads.

  Further, in a bearing used in an environment exceeding 390K, low temperature tempered steel undergoes a structural change and cannot be used because it softens and changes in dimensions. Therefore, high temperature tempered type high carbon high alloy steels such as M50 (0.8C-4Cr-4.3Mo-1V) and T1 (0.7C-4Cr-18W-1V) are used.

  However, conventional bearing steels have the following drawbacks.

  That is, bare-hardened steel is less likely to lower the oxygen content in terms of melting and refining than high-carbon chromium bearing steel, tends to produce oxide-based non-metallic inclusions, and causes a reduction in rolling life.

  High carbon high alloy steel also tends to produce giant carbides that reduce the rolling life.

  In this respect, high carbon chrome bearing steel does not have such disadvantages and can achieve high processing accuracy, so it is suitable for use in rotating parts of precision equipment that requires particularly low noise during rotation. Yes. However, high carbon chromium bearing steel is easily rusted, and it is necessary to apply rust preventive oil to the outer surface, and gasification of this rust preventive oil may cause malfunction of precision equipment.

  Therefore, martensitic stainless steel equivalent to SUS440C steel, which is excellent in corrosion resistance and wear resistance, is used for bearings used in a corrosive atmosphere. However, this stainless steel contains non-metallic inclusions such as eutectic carbides generated by eutectic reaction when molten steel solidifies and alumina that is generated by chemical changes in the impurities of the raw materials in the molten steel. When machining, there is a difference in machinability between the eutectic carbides and non-metallic inclusions and the steel structure, and high-precision cutting cannot be performed. Since the groove cannot be machined with high accuracy, noise generated by vibration during rotation is large and cannot be used for a rotating part of a precision instrument.

  Therefore, as a rolling bearing having excellent quietness and excellent wear resistance and corrosion resistance, Patent Document 1 states that “a plurality of balls made of high carbon chromium bearing steel are provided between inner and outer rings, and at least the inner ring and the outer ring are provided. On the other hand, a “ball bearing” is proposed which is composed of martensitic stainless steel having a hardness of HRC58 or higher and a eutectic carbide diameter of 10 μm or less.

Patent Document 2 discloses that in a rolling bearing made of stainless steel in which a plurality of rolling elements are interposed between an outer race and an inner race, the stainless steel has a weight ratio of C: 0.6-0. .75%, Si: 0.1 to 0.8%, Mn: 0.3 to 0.8%, Cr: 10.5 to 13.5%, balance Fe and inevitably mixed impurities, There has been proposed a “rolling bearing” characterized in that the eutectic carbide contained therein has a major axis of 20 μm or less and an area ratio of 10% or less.
Japanese Patent Laid-Open No. 6-117439 Japanese Patent Publication No.5-2734

  When the eutectic carbides become huge, if the huge carbides appear on the bearing surface, it is difficult to make a correct finished surface shape due to the difference in machinability between the carbides and the surrounding base as described above. There is a problem with silence during rotation. In addition, the giant carbide causes a difference in wear resistance with the surrounding base during use as a bearing, cracks and drops off from the surface, thereby disturbing the surface shape and significantly reducing the quietness. Therefore, it is preferable to reduce the size of the carbide as much as possible because it is difficult for the carbide to appear on the bearing surface. As described in the above-mentioned patent document, it is quiet to reduce the diameter of the carbide to 20 μm or less or 10 μm or less. Effective in improving sex. However, it is not possible to obtain a satisfactory level of quietness simply by reducing the size of the carbide. On the other hand, in order to reduce the carbide diameter as such, an additional step in manufacturing technology is required, which causes a significant increase in manufacturing cost, which is not a practical means.

  The present invention has been made in view of such problems of the prior art, and its purpose is excellent in quietness and corrosion resistance and life resistance (corresponding to wear resistance). Another object is to provide a low-cost rolling bearing.

  The inventor found that the maximum length of eutectic carbide in stainless steel, the average value of the equivalent circle diameter of eutectic carbide, the average area of eutectic carbide, the area ratio of eutectic carbide, the form of eutectic carbide and the form of stainless steel Focusing on the hardness and the amount of retained austenite in stainless steel, the present invention intensively studied the relationship between these values and machinability (workability), quietness as a rolling bearing, life resistance, and manufacturing cost. As a result.

  That is, it is clear that reducing the maximum major axis of eutectic carbide is effective in improving the quietness of the rolling bearing, but in reality, the number of eutectic carbides having a maximum major axis of more than 20 μm is extremely small. Moreover, the probability that the large eutectic carbide appears on the surface in contact with the rolling elements is extremely low. In addition, it is difficult to eliminate the generation of eutectic carbides having a maximum major axis of more than 20 μm with a general manufacturing technique for mass production processes, which requires an extra additional process, greatly increasing the manufacturing cost. Raise. In this respect, when considering the manufacturing cost, it is preferable that the eutectic carbide has a major axis of 30 μm or less because a certain effect can be obtained in improving machinability and the manufacturing cost is not increased.

  In addition, the average value of the equivalent circle diameter of the eutectic carbide is generally about 2.0 to 2.8 μm, but reducing the average value of the equivalent circle diameter is effective for improving the machinability. Yes, it is preferably 0.3 to 1.6 μm. In addition, the average value of the equivalent circle diameter means the average value of the diameters when the area of each eutectic carbide is obtained by an image analyzer and the area is converted into a circle.

Further, the average area of the eutectic carbide is generally about 3.0 to 6.0 μm ² , but reducing this average area is effective in improving machinability, and it is 0.1 to 2 μm. ² is preferable.

  In order to improve machinability, it is preferable to limit the absolute amount of the eutectic carbide, and therefore, the area ratio of the eutectic carbide is preferably 2 to 7%. In addition, an area ratio means the ratio (percentage) of the total area of the eutectic carbide which occupies for the total measurement area of a visual field.

Further, the usual eutectic carbide forms include Cr ₂₃ C ₆ , Cr ₃ C ₂ , Cr ₇ C ₃ , Fe ₃ C, (Cr, Fe) ₂₃ C _6, etc., which are used for conventional rolling bearings. In the martensitic stainless steel, the eutectic carbide having the form of Cr ₂₃ C ₆ is 90 to 95%, and the remainder is Cr ₃ C ₂ , Cr ₇ C ₃ , Fe ₃ C, (Cr, Fe). ₂₃ C ₆ etc. From the viewpoint of machinability, quietness, life resistance, etc., brittle Cr carbide is preferable to brittle Fe carbide, and among Cr carbides, there are many eutectic carbides having a low hardness of Cr ₂₃ C _6. This is more effective in improving machinability, quietness, and life resistance. In this respect, it is preferable that the form of eutectic carbide is 98% or more of Cr ₂₃ C ₆ . Further, in order to ensure the rolling life of the raceway surface or the rolling surface and the wear resistance and toughness, the hardness of the stainless steel is preferably 58 to 62 on the Rockwell hardness C scale (HRC).

  In order not to cause harmful permanent deformation on the raceway surface or the rolling surface due to a load or an impact, it is necessary to reduce the amount of retained austenite, and it is preferably 6% by volume or less. By suppressing the amount of retained austenite to a small amount, it is possible to prevent the surface accuracy of the raceway surface or rolling surface from being deteriorated over time, in addition to the effect of improving the pressure-resistance scar property of the raceway surface or rolling surface.

  The present invention is configured as described above, and can provide a low-cost rolling bearing having excellent quietness and corrosion resistance and life resistance. In particular, the present invention is a large industrial effect that contributes to cost reduction and quietness improvement of precision equipment such as VTRs and computer peripherals.

That is, according to the present invention, in a rolling bearing comprising a plurality of rolling elements between an inner ring and an outer ring, at least one of the inner ring and the outer ring is martensitic stainless steel, and stainless steel is contained as the stainless steel. The major axis of the eutectic carbide is 30 μm or less, the average value of the equivalent circle diameter of the eutectic carbide is 0.3 to 1.6 μm, the average area of the eutectic carbide is 0.1 to ² μm ² , The area ratio of the eutectic carbide is 2 to 7%, the form of the eutectic carbide is 98% or more of Cr ₂₃ C ₆ , the hardness of the stainless steel is HRC 58 to 62, and the residual in the stainless steel A rolling bearing characterized by using an austenite amount of 6% by volume or less is a first device,
In a rolling bearing having a rolling groove formed on the outer periphery of a shaft and a plurality of rolling elements between the rolling groove and a rolling groove on the inner periphery of the outer ring, at least one of the inner ring and the outer ring is martensite. The major axis of the eutectic carbide contained in the stainless steel is 30 μm or less, and the average value of the equivalent circle diameter of the eutectic carbide is 0.3 to 1.6 μm. The average area of the crystal carbide is 0.1 to ² μm ² , the area ratio of the eutectic carbide is 2 to 7%, the form of the eutectic carbide is 98% or more of Cr ₂₃ C ₆ , stainless steel The second bearing is a rolling bearing characterized in that the hardness of HRC is 58 to 62 and the amount of retained austenite in stainless steel is 6% by volume or less.

  In the present invention, “silence” means that “a certain metallic material is processed into rolling elements or inner or outer rings and assembled into a rolling bearing, and when the bearing is incorporated into a precision instrument and operated, the noise generated by the precision instrument is reduced. Among them, it means “low noise caused by metal materials”. The noise is caused by the vibration generated during the rotation operation of the rolling bearing, and the generation of this vibration greatly depends on the shape accuracy of the rolling elements, the inner ring, and the outer ring as described above. The relatively small rolling bearing used in the precision equipment field is an important issue that is quiet so as not to be a problem in other applications.

  Therefore, when at least one of the inner ring and the outer ring is made of martensitic stainless steel, rust is hardly generated, and the corrosion resistance and the life resistance can be improved.

  And by making the elongate diameter of the eutectic carbide contained in the stainless steel 30 μm or less, the machinability can be improved without increasing the production cost.

In addition, the average value of the equivalent circle diameter of the eutectic carbide is set to 1.6 μm or less, the average area of the eutectic carbide is set to 2 μm ² or less, and the area ratio of the eutectic carbide is set to 7% or less. Can be further improved, and quietness can be greatly improved.

However, in order to excessively reduce the average value, the average area, and the area ratio of the equivalent-circle diameter of the eutectic carbide, a special manufacturing process for that purpose is required, leading to a significant increase in manufacturing cost. Therefore, if the average value of the equivalent circle diameter of the eutectic carbide is 0.3 μm or more, the average area of the eutectic carbide is 0.1 μm ² or more, and the area ratio of the eutectic carbide is in the range of 2% or more, almost Since it can be manufactured according to the normal manufacturing process, an economical manufacturing system can be achieved with almost no increase in manufacturing cost.

Furthermore, the form of the eutectic carbide can improve machinability, quietness, life resistance, etc. by setting Cr ₂₃ C ₆ to 98% or more.

  Further, by setting the hardness of the stainless steel to HRC 58 to 62, it is possible to ensure the rolling life, wear resistance, and toughness of the raceway surface or the rolling surface.

  And by making the amount of retained austenite in stainless steel 6 volume% or less, a pressure-proof mark property can be improved and the time-dependent deterioration of the surface precision of a raceway surface or a rolling surface can be prevented.

  The reasons for limiting the components (% by weight) of the stainless steel of the present invention are as follows.

  C is an essential constituent element for imparting high-temperature strength and wear resistance, and 0.6% or more is necessary, but if it is too much, a large eutectic carbide is generated, and machinability is reduced. Since corrosion resistance also worsens, it is preferable to set it as 0.75% or less.

  Si is 1% or less, Mn is 1% or less, P is 0.03% or less, S is 0.02% or less, Mo is 0.3% or less, V is 0.15% or less, Ti is 15 ppm or less, O 35 ppm or less is because when these elements are too much, work hardening is promoted and machinability is lowered, so that machinability is not lowered and formation of non-metallic inclusions is suppressed. This element is kept below the above numerical value. Furthermore, when there are too many such elements, there are also disadvantages that the hardenability is lowered and the martensite conversion rate is lowered.

  Since Cr combines with C to form a carbide and enhances the life resistance and Cr dissolved in the matrix increases the corrosion resistance, 11.5% or more is necessary. However, if the amount is too large, the quenching hardness decreases, so Cr is preferably 13.5% or less in relation to the C content.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments.

In FIG. 1, 1 is an outer ring, 2 is an inner ring, and 3 is a rolling element. A plurality of rolling elements 3 made of high carbon chromium bearing steel (SUJ2) are filled between the rolling grooves 4 on the inner periphery of the outer ring 1 and the rolling grooves 5 on the outer periphery of the inner ring 2. In the case where martensitic stainless steel having the composition (% by weight) shown in Table 1 is used as the material of the outer ring 1 and the inner ring 2 (Example 1), only the material of the outer ring 1 is shown in Table 1. Of martensitic stainless steel and the inner ring 2 is made of high carbon chromium bearing steel (SUJ2) (Example 2). The average value of the area ratio, maximum long diameter, and equivalent circle diameter of the eutectic carbide contained in the stainless steel. Table 2 shows the ratio (%) of Cr ₂₃ C _{6 in} the average area and eutectic carbide form, as well as the Rockwell hardness C scale (HRC) of stainless steel and the amount of retained austenite (volume%) in stainless steel. As shown in

In FIG. 2, a plurality of rolling elements 3 made of high carbon chromium bearing steel (SUJ2) are filled between the rolling groove 7 carved on the outer periphery of the shaft 6 and the rolling groove 4 on the inner periphery of the outer ring 1. (Example 3). In Example 3, martensitic stainless steel having the composition shown in Table 1 was used as the material for the outer ring 1 and the shaft 6, and high-carbon chromium bearing steel (SUJ2) was used as the rolling element 3. In this case, the area ratio of eutectic carbide contained in stainless steel, maximum long diameter, average value of equivalent circle diameter, average area and ratio of Cr ₂₃ C ₆ in the form of eutectic carbide (%) and stainless steel rockwell Table 2 shows the hardness C scale (HRC) and the amount of retained austenite (volume%) in the stainless steel. In Example 3, both the outer ring 1 and the shaft 6 are martensitic stainless steel, but depending on the use conditions, only one that requires corrosion resistance and high temperature strength can be martensitic stainless steel.

  In obtaining the martensitic stainless steel, water quenching was performed from 1025 ° C., followed by subzero treatment (−80 ° C.) and tempering to 170 ° C.

  The area ratio of eutectic carbide in stainless steel, the maximum major axis, the average value of the equivalent circle diameter, the average area, and the form of eutectic carbide are the control of impurity elements, the preparation and refining of raw materials, and the manufacturing process such as ingot forming. It can be controlled by manufacturing conditions (for example, refining time, degassing conditions, insertion of a diffusion heat treatment step, etc.). However, in order to make the maximum major axis of the eutectic carbide 20 μm or less, the number of manufacturing steps increases using a special raw material, which causes a significant increase in manufacturing cost.

  The hardness of stainless steel and the amount of retained austenite in the stainless steel can be controlled by the heating temperature and heating time during quenching, the cooling rate, the cooling medium, the cooling temperature and time, the tempering temperature and the tempering time, and the like.

  Results (Anderon value) of vibration and noise evaluation tests on rolling bearings of Examples 1 to 3 in accordance with the standard of AFBMA (The Anti-Friction Bearing Manufacturers Association, Inc.) and the processing of these rolling bearings Table 2 shows properties (machinability), life resistance, and cost expressed in indexes.

Table 2 also shows the evaluation results of Comparative Examples 1 to 3 and Conventional Examples 1 and 2 at the same time. In Comparative Examples 1 to 3, as in Example 1, the rolling element 3 is a high carbon chromium bearing steel. The martensitic stainless steel having the composition shown in Table 1 is used as the material of the outer ring 1 and the inner ring 2, and the area ratio, maximum long diameter, average value of equivalent circle diameter, average area of the eutectic carbide contained in the stainless steel Further, at least one characteristic value out of the ratio (%) of Cr ₂₃ C ₆ in the form of eutectic carbide and the amount of retained austenite (volume%) in stainless steel is out of the scope of the present invention. Conventional examples 1 and 2 are all martensitic stainless steels having the composition shown in Table 1 for the materials of outer ring 1, inner ring 2 and rolling element 3, and the average equivalent circle diameter of eutectic carbide contained in stainless steel. Value, average area and at least one characteristic value of Cr ₂₃ C ₆ ratio (%) in the form of eutectic carbide and the amount of retained austenite (volume%) in stainless steel are within the scope of the present invention. It is something that comes off.

  In Table 2, M and H of the Anderon values are divisions of the measurement frequency band, M represents a medium frequency band (300 to 1800 Hz), and H represents a high frequency band (1800 to 10000 Hz). In the same frequency band, the lower the Anderon value, the better the quietness.

About workability, lifetime resistance, and cost, it displays with the index | exponent which set the prior art example 1 to 100, and the one where a numerical value is smaller shows that these characteristics are excellent. In addition, the workability is evaluated by performing a peripheral measurement and a parting cut by a precision lathe and performing a comparative measurement of increments of additional current, and the evaluation of the life resistance is 20 ° C., 80 ° C., This was performed by heating at a temperature such as 100 ° C. for a certain period of time, rotating for a total of about 1000 hours, and comparing the subsequent rotation tone (sound, vibration, etc.) and the grease state.
From Table 2, the following can be pointed out.
(1) Since the area ratio, the maximum major axis, the average value of the equivalent circle diameter and the average area of the carbide of Comparative Example 2 are the smallest, the Anderon value is low. However, a special manufacturing process is required to lower these numerical values, and the manufacturing cost for that is extremely high, which is not an economical material. Further, the form of carbide is as low as 95% Cr ₂₃ C ₆ and Fe ₃ C, Cr ₇ C ₃ , Cr ₃ C _2, etc. are present, so it cannot be said that the life resistance is so excellent.
(2) In Comparative Example 1 and Conventional Examples 1 and 2, the maximum major axis of the carbide is shorter than those in Examples 1 to 3, but the average value and the average area of the equivalent circle diameter are out of the scope of the present invention. Anderon value is greater than ~ 3. Further, these Comparative Example 1 and Conventional Examples 1 and 2 are more expensive than Examples 1 to 3 in order to reduce the maximum major axis of the carbide, and in particular, the maximum major axis of the carbides of Conventional Example 2 and Comparative Example 1 is Since these are as small as 8 μm and 12 μm, respectively, and the average value of the equivalent circle diameter is relatively small, the manufacturing cost therefor is extremely high.
(3) In Comparative Example 3, the carbide area ratio, the maximum major axis, the average value of the equivalent circle diameter and the average area are all outside the scope of the present invention, and the Anderon value is extremely large.
(4) Compared with the above comparative examples and conventional examples, Examples 1 to 3 have an appropriate area ratio, maximum major axis, average value of equivalent circle diameter, and average area within the scope of the present invention regarding carbides. The ratio of Cr ₂₃ C ₆ in carbide form (%), the hardness of stainless steel, and the amount of retained austenite (volume%) in stainless steel also have appropriate values within the scope of the present invention. Therefore, the Anderon value is a level comparable to that of Comparative Example 2, and all of the workability, life resistance, and cost are better than the conventional example.

The relationship between the average value of these equivalent circle diameters and the Anderon value (M) is shown in FIG. 3, the relationship between the maximum long diameter and the cost index is shown in FIG. 4, and the ratio (%) of Cr ₂₃ C ₆ in the form of carbides Fig. 5 shows the relationship of the life resistance index. 3, 4, and 5, “◎” indicates an example, “▲” indicates a comparative example, and “●” indicates a conventional example. 3, 4, and 5 clearly show the characteristics of the present invention that the Anderon value is low, the cost is low, and the lifetime is high.

In FIG. 4, the cost is the lowest in Comparative Example 3, but the Comparative Example 3 has a very high Anderon value as shown in FIG. Further, in FIG. 3, the Anderon value of Comparative Example 2 is extremely low, but the cost of Comparative Example 2 is extremely high as shown in FIG. Further, in FIG. 5, the vicinity of the ratio (%) = 98% of Cr ₂₃ C ₆ in the form of carbides resistant service life changes rapidly as the critical point, the ratio of Cr ₂₃ C ₆ and 98% This shows that the life resistance is greatly improved.

  The area ratio, the maximum major axis, the average value of the equivalent circle diameter and the average area of the carbides in Table 2 were obtained by embedding a stainless steel specimen in a resin, polishing it, observing it with a metal microscope, and taking a representative field of view at a magnification of 400 times. It is the result measured by the image analyzer.

  Since it is rarely expected that the eutectic carbide of the longest diameter will appear on the polished surface, the rolling bearing is dissolved in an acid solution by constant current electrolysis, the carbide is filtered through a filter, and a scanning electron microscope ( FIG. 6 shows the result (2000 times) of the structure observation by SEM). In FIG. 6, a white lump portion shows carbide.

  The morphology analysis of the eutectic carbide of stainless steel was performed by X-ray diffraction qualitative analysis after treating the sample by electrolytic extraction. The analysis conditions are: the target is Cu, the acceleration voltage is 40 kV, the sample current is 200 mA, and the measurement angle (2θ) is 5 to 100 °. The analysis method was performed by measuring the X-ray diffraction waveform and searching the library for compound forms.

As a result, the spectral intensity ratios of the compounds identified as carbides were compared, and when Cr ₂₃ C ₆ showed a certain spectral intensity ratio S1 and no other carbides were identified, eutectic in stainless steel. The form of carbide is 100% Cr ₂₃ C ₆ .

On the other hand, when the spectral intensity ratio S2 has some form of carbide other than Cr ₂₃ C ₆ , the eutectic carbide in the stainless steel is composed of Cr ₂₃ C ₆ and other forms of carbide. The ratio of Cr ₂₃ C ₆ is (S1 / (S1 + S2)) × 100 (%).

  The volume (%) of retained austenite in stainless steel was measured by surface X-ray diffraction after treating the sample by electrolytic extraction. As analysis conditions, the target is Cu, the acceleration voltage is 40 kV, the sample current is 180 mA, and the scanning range is 41.2 to 46.705 °. The analysis method was performed by identifying the crystal structure from the integrated intensity of diffraction lines having Miller indices h, k, and l and determining the relative capacity ratio of the retained austenite amount.

  As the X-ray diffractometer, RINT 1500/2000 type manufactured by Rigaku Corporation was used.

It is a longitudinal cross-sectional view of the Example of the rolling bearing of this invention. It is a longitudinal cross-sectional view of another Example of the rolling bearing of this invention. It is a figure which shows the relationship between the average value (micrometer) of a circle equivalent diameter of eutectic carbide, and an Anderon value (M). It is a figure which shows the relationship between the largest long diameter (micrometer) of a eutectic carbide, and a cost index. Form of eutectic carbide is a diagram showing the relationship耐寿life index the ratio (%) of the compound is Cr ₂₃ C _6. It is a figure which shows the SEM image of the carbide | carbonized_material which precipitated on stainless steel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer ring 2 ... Inner ring 3 ... Rolling element 4, 5, 7 ... Rolling groove 6 ... Shaft

Claims (2)

In a rolling bearing provided with a plurality of rolling elements between an inner ring and an outer ring, at least one of the inner ring and the outer ring is martensitic stainless steel, and as this stainless steel, the major axis of the eutectic carbide contained in the stainless steel is The average equivalent circle diameter of the eutectic carbide is 0.3 to 1.6 μm, the average area of the eutectic carbide is 0.1 to ² μm ² , and the area of the eutectic carbide is 30 μm or less. The rate of the eutectic carbide is 98% or more of Cr ₂₃ C ₆ , the hardness of stainless steel is HRC 58 to 62, and the amount of retained austenite in the stainless steel is 6% by volume or less. A rolling bearing characterized by using the following. In a rolling bearing having a rolling groove formed on the outer periphery of a shaft and a plurality of rolling elements between the rolling groove and a rolling groove on the inner periphery of the outer ring, at least one of the inner ring and the outer ring is martensite. The major axis of the eutectic carbide contained in the stainless steel is 30 μm or less, and the average value of the equivalent circle diameter of the eutectic carbide is 0.3 to 1.6 μm. The average area of the crystal carbide is 0.1 to ² μm ² , the area ratio of the eutectic carbide is 2 to 7%, and the form of the eutectic carbide is 98% or more of Cr ₂₃ C _6. A rolling bearing characterized in that the hardness of the steel is HRC 58 to 62 and the amount of retained austenite in the stainless steel is 6% by volume or less.

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