JP3435799B2 - Rolling bearing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing used in automobiles, agricultural machines, construction machines, steel machines, etc., and particularly under high temperature and under lubrication containing foreign matter (for example, foreign matter is mixed in the lubricant in the bearing). The present invention relates to a rolling bearing suitable for a transmission or an engine, which can maintain good dimensional stability and a long rolling life in a running state).

[0002]

2. Description of the Related Art One of the factors that shorten the life of rolling bearings is that, for example, foreign matter (metal chips, burrs, abrasion powder, etc.) mixes in the lubricant supplied into the bearings, causing the bearings to move. This foreign substance may damage the inner ring, the outer ring, and the rolling elements during operation. When foreign matter is mixed in the lubricant in the bearing, the life of the bearing may be shortened to about one tenth of that in the case where the foreign matter is hardly mixed.

In order to improve the shortening of the life of the bearing due to the inclusion of such foreign matter, Japanese Patent Laid-Open No. 64-55423 discloses that the carbon content of the alloy steel forming the inner ring, the outer ring, and the rolling elements, and the respective members. It is disclosed that the amount of retained austenite in the surface layer is limited to a predetermined range. on the other hand,
In recent years, as the output of the engine has increased, the bearings incorporated in the transmission and the engine have become hot (130 to 170).
Therefore, a bearing with a long rolling life at high temperatures is required.

As a bearing having such a long rolling life under high temperature, Japanese Patent Laid-Open No. 3-82736 discloses an inner ring made of an alloy steel obtained by adding elements such as Si, Cr, Mo and V to low-medium carbon steel. It is disclosed that at least one of the outer ring, the outer ring and the rolling element is formed, and this is carburized or carbonitrided and then quenched and tempered at a high temperature so that the average retained austenite amount is 3% or less.

When tempering at a high temperature in order to increase the dimensional stability at a high temperature, the hardness generally decreases, but here, Si, Cr, Mo, V, etc. are added to the low-medium carbon steel. The decrease in hardness due to such high temperature tempering is suppressed. Further, after carburizing or carbonitriding, quenching, and tempering, carbides of Cr, Mo, and V are present in the surface layer of the alloy steel. Therefore, the surface layer of the inner ring, outer ring, or rolling element should be hardened. You can From these, the wear resistance of each member at high temperature improves,
This bearing has a long rolling life.

Further, in Japanese Patent Laid-Open No. 3-153842, at least one of an inner ring, an outer ring and a rolling element is made of an alloy steel obtained by adding elements such as Si, Cr, Mn and (Mo) to medium carbon steel. It is disclosed that a steel sheet was formed, carbonitrided, and then quenched and high temperature tempered. This also suppresses the decrease in hardness due to high temperature tempering and improves the wear resistance of each member at high temperatures, so that a rolling bearing having a long rolling life can be obtained.

[0007]

However, among the above-mentioned conventional techniques, the technique disclosed in Japanese Patent Laid-Open No. 64-55423 aims to improve the life of the bearing due to the inclusion of foreign matter. No. 82736 and Japanese Unexamined Patent Publication No. HEI 3-
In the technology disclosed in Japanese Patent No. 153842, the purpose is to improve the rolling life under high temperature, and in any case, considering the case where the rolling bearing is used under high temperature and foreign matter-containing lubrication. I didn't put it in.

The present invention relates to such an improvement of the prior art, and has good dimensional stability and long rolling life under the condition that the temperature is high and foreign matters are mixed in the lubricant in the bearing. It is an object of the present invention to provide a rolling bearing that can hold both of these.

[0009]

In order to achieve the above object, in a rolling bearing of the present invention, an inner ring, an outer ring and a rolling element made of alloy steel are carburized or carbonitrided and then quenched and tempered. Do not Luke, or quenching Te,
In the rolling bearing which is tempered, the alloy steel is
C is 0.10 to 1.00% by weight and Cr is 0.50 to 3.
00% by weight, 0.15 to 1.00% by weight of Si, and 0.20 to 1.50% by weight of Mn, with the balance being F
e and impurities that are inevitably mixed, and of the inner ring and the outer ring, at least the inner ring has an average retained austenite amount of 4% by volume or less, and the rolling element has an average retained austenite amount of 20 to 30% by volume. It is characterized by that.

Here, the average retained austenite amount means a value obtained by dividing the entire retained austenite amount from the surface to the core portion by the total volume of the member, not only the surface layer portion of the member. In addition, after performing carburizing treatment or carbonitriding treatment on at least the inner ring of the inner ring and the outer ring formed of alloy steel having a C content of less than 0.80% by weight,
It is preferable to perform quenching and high temperature tempering.

[0011]

In the present invention, as the alloy steel forming the inner ring, the outer ring and the rolling elements forming the rolling bearing, C is 0.10 to 1.00% by weight and Cr is 0.50 to 3.00.
%, Si 0.15 to 1.00% by weight, Mn 0.
The thing contained in each ratio of 20-1.50 weight% is used, and the reason is as follows. <C: 0.10 to 1.00% by weight> This is the same as the carbon content of the case-hardening steel and the bearing steel, which are ordinary bearing materials. If the C content is less than 0.10% by weight, the time required for carburizing or carbonitriding becomes long. If the C content exceeds 1.00% by weight, huge carbides are formed in the surface layer.

In particular, in the alloy steel forming at least the inner ring of the inner ring and the outer ring, the C content is 0.10.
By adjusting the amount to be 0.80% by weight, the average retained austenite amount can be suppressed small. On the other hand, regarding the alloy steel forming the rolling elements, the content ratio of C is 0.80 to 0.80.
By increasing the amount to 1.00% by weight, the average retained austenite amount can be increased simply by quenching and tempering without carburizing or carbonitriding. Further, in this way, if the average retained austenite amount is increased without carburizing or carbonitriding treatment, there is almost no difference in the retained austenite amount between the surface layer portion and the core portion. At this time, the average retained austenite amount can be determined only by measuring the surface layer portion. <Cr: 0.50 to 3.00 wt%> This makes it possible to deposit a large amount of carbides, carbonitrides, and chromium nitrides, and to make the grain sizes of these fine. If the Cr content is less than 0.50% by weight, the carbides are likely to become large during carburizing or carbonitriding. If the content of Cr exceeds 3.00% by weight, Cr oxides are formed on the surface and it becomes difficult for carbon and nitrogen to enter, so that the carburizing and carbonitriding characteristics deteriorate. <Si: 0.15 to 1.00% by weight> This improves the mechanical properties and heat treatment properties. If the Si content is less than 0.15% by weight, the toughness of the core part will be deteriorated, and if it exceeds 1.00% by weight, it becomes difficult for carbon and nitrogen to enter from the surface, resulting in carburizing and carbonitriding characteristics. descend. <Mn: 0.20 to 1.50% by weight> This improves the hardenability, so that the toughness can be made high after quenching. If the Mn content is less than 0.20% by weight, its action is not sufficiently exhibited, and if it exceeds 1.50% by weight, the machinability and hot workability of the alloy steel deteriorate.

In addition to this, in the present invention, the average retained austenite amount is limited for at least the inner ring and the rolling elements of the races and the rolling elements that constitute the rolling bearing. Since retained austenite is converted to martensite over time, those containing retained austenite undergo a dimensional change with time. Therefore, when a material having a large amount of retained austenite is used at high temperature, decomposition of austenite (formation of martensite) is promoted, and the amount of dimensional change that occurs is also large.

Here, according to the following equations (1) and (2) relating to the amount of decomposition of the retained austenite amount, an experiment was carried out in which the alloy steels having different initial retained austenite amounts were held at a constant temperature for a certain period of time. Was calculated. Δγ _R = γ _R0 (1−e ^−Kt ) (1) (Δγ _R : Decomposition amount of retained austenite γ _R0 : Initial average retained austenite amount t: Retention time K: Austenite decomposition rate constant) logK = A− (B / T) (2) (A, B: constant T determined by the chemical composition of the alloy steel T: holding temperature) As a result, the chemical composition of the alloy steel used has a C of 0.10.
~ 1.00% by weight, 0.50 to 3.00% by weight of Cr,
Si 0.15 to 1.00 wt%, Mn 0.20 to
When the content is 1.50% by weight, the initial average retained austenite amount that can reduce the amount of retained austenite decomposed below a predetermined value is 4% by volume or less for the inner ring and the outer ring, and 20 to 30% by volume for the rolling elements. It was A more preferable value for the average retained austenite amount is 2 to 4% by volume for the inner ring and the outer ring, and 25 for the rolling elements.
Was -30% by volume.

On the other hand, as disclosed in the above-mentioned Japanese Patent Laid-Open No. 64-55423, when a rolling bearing is used under lubrication containing foreign matter, as shown in a sectional view in FIG. The repeated contact causes an indentation on the surface 2 of the raceway surface 1, stress concentrates on the edge portion 2a of the indentation 2, and the microcracks spread from there to the surroundings. As the ratio "r / c" between the curvature r of the edge portion 2a and the radius c of the indentation 2 is larger, the stress concentration at the edge portion 2a can be relaxed.

Here, as a result of examining the relationship between the "r / c" value and the amount of retained austenite (see FIG. 5 of this publication).
Therefore, when the retained austenite amount is 45% by volume or less, the “r / c” value increases as the retained austenite amount increases. Therefore, increase the retained austenite amount and increase the “r / c” value. As a result, the concentration of stress on the edge portion 2a can be relieved, and the indentation damage generated on the raceway surface 1 can be reduced. Then, specifically, it is disclosed that when the amount of retained austenite in the surface layer portion is in the range of 20 to 45% by volume, the rolling life can be extended under the foreign matter-containing lubrication.

However, when the rolling bearing is used under the condition of being mixed with foreign matter and under high temperature, if the residual austenite amount of the inner ring, the outer ring and the rolling elements constituting the rolling bearing is large, As described above, the dimensional change is large, which is not preferable. Specifically, an increase in the inner diameter of the inner ring causes a lack of fit between the inner ring and the shaft, and a decrease in the radial internal clearance makes smooth rotation impossible. Therefore, from the viewpoint of ensuring the dimensional accuracy at high temperatures, it is necessary to reduce the average retained austenite amount of each member constituting the rolling bearing.

In consideration of the fact that the dimensional change is severely limited among the bearing rings, especially in the inner ring, in the rolling bearing of the present invention, the average residual of at least the inner ring of the bearing rings is summarized. By reducing the austenite amount to 4% by volume or less and increasing the average retained austenite amount of the rolling elements to 20 to 30% by volume, even if foreign matter is used in a state of being mixed between the races and the rolling elements, Indentation damage that occurs on the bearing ring can be reduced and dimensional changes can be reduced even when used at high temperatures.

[0019]

EXAMPLES The present invention will be described in detail below with reference to examples. For single-row deep groove ball bearings using steels A (C content 0.42% by weight) and B (C content 0.96% by weight) having the chemical compositions shown in Table 1 below, which are within the scope of the present invention. Inner ring, outer ring, and rolling elements (balls) were formed. And A
As shown in FIG. 2, for the inner ring, the outer ring, and the rolling elements obtained from steel, (a) endothermic gas, enriched gas, and 5 vol% NH ₃ (ammonia) at 870 to 890 ° C. for 4 hours. ) After performing carbonitriding treatment in an atmosphere furnace composed of gas and oil quenching, (b) 820 to 840 ° C.
After heating for 30 minutes at 30 ° C. and oil quenching, (c) 22
High temperature tempering was performed at 0 to 240 ° C. for 100 minutes. Also,
For the steel B obtained, as shown in FIG.
(B) After heating at 860 to 880 ° C. for 30 minutes and then quenching, (c) tempering was performed at 160 to 180 ° C. for 100 minutes.

[0020]

[Table 1]

Further, SUJ2 (JIS high carbon chrome bearing steel) was used to form inner races, outer races, and rolling elements (balls) for single-row deep groove ball bearings similar to the above, and quenching (heating temperature 840). C., heating time 30 minutes, oil quenching) and tempering (heating temperature 160.degree. C., heating time 100 minutes). Further, rolling elements similar to those described above were formed from SUJ2, followed by quenching (heating temperature 950 ° C., heating time 30 minutes, oil quenching) and tempering (heating temperature 160 ° C., heating time 100 minutes). This high temperature quenched product is SU
Displayed as J2 ^* . In addition, an inner ring similar to the above was formed by SUJ2, and was quenched (heating temperature 840 ° C, heating time 30 minutes, oil quenching), tempering (heating temperature 230 ° C,
The heating time was 100 minutes). This high temperature tempered product is indicated as "SUJ2 ^** ".

The distribution of the amount of retained austenite from the surface to the core was measured for the inner ring formed of A steel, which was carbonitrided, quenched and tempered as described above. The results are shown graphically in FIG. As can be seen from this graph, the amount of retained austenite in the surface layer portion of this inner ring is 26.0% by volume, and this amount decreases rapidly toward the core portion up to a distance of 0.4 mm from the surface. From this point onward, it is saturated at about 2.0% by volume. A value obtained by dividing the total retained austenite amount by the inner ring volume (average retained austenite amount)
Was 4% by volume. Further, the average retained austenite amount was calculated in the same manner for the outer ring and the rolling elements formed of the A steel which were carbonitrided, quenched, and tempered.

Further, the inner and outer rings made of B steel and SUJ2, those obtained by quenching and tempering the rolling elements, and SU
The average retained austenite amount was calculated in the same manner for the rolling element made of J2 ^* and the inner ring made of SUJ2 ^** .
These B steels, SUJ2, SUJ2 ^* , and SUJ2 ^**
Since the carbonaceous nitriding treatment was not carbonitrided, the amount of retained austenite was substantially constant in the depth direction, and the amount of retained austenite in the surface layer and the average amount of retained austenite were approximately the same value.

Further, the Vickers hardness H _v was measured for each member of each bearing. The inner races, outer races, and rolling elements thus obtained are listed in Table 2 and Table 3 below.
The single row deep groove ball bearings of Examples 1 to 4 and Comparative Examples 1 to 7 were assembled in combination as shown in FIG. The bearing has an outer diameter of 62 mm, an inner diameter of 47 mm and a width of 16 mm. <Dimensional Stability Test> Examples 1, 3, 4 and Comparative Example 1, assembled with the combinations shown in Table 2 below.
A test for checking dimensional stability at 170 ° C. was performed on each of the bearings 2 and 7.

That is, when a bearing having a radial internal clearance (hereinafter, simply referred to as “internal clearance”) of 31 μm was press-fitted onto a shaft having a diameter of 30 mm with an interference of 17 μm,
The radial internal clearance after press fitting was 18 μm. This was placed in a tempering furnace and held at 170 ° C. for 1000 hours, and then the press-fit state of each bearing on the shaft was examined. After the test, the bearing was removed from the shaft, and the inner diameter of the inner ring and the internal clearance were measured.

The results are also shown in Table 2. In addition,
For the inner diameter, and a reference diameter D ₀ of the shaft, the value of the difference "D _N -D _0" between the measured inner ring inner diameter (diameter) D _N, is shown in Table 2 as the inner diameter difference. Therefore, if this inner diameter difference "D _N -D ₀ " is -17 μm, it means that the inner diameter of the inner ring has not changed. In addition, the result of the press-fitting state on the shaft is "OK" if the press-fitting state is sufficient.
If the shaft can be easily removed from the bearing, it is displayed as "disengaged." Further, in the table, "average retained austenite amount" is abbreviated as "average γ _R ".

[0027]

[Table 2]

As can be seen from Table 2, Examples 1, 3, 4
With regard to the bearing of Comparative Example 2, since the average retained austenite amount of both the inner ring and the outer ring was 4% by volume or less, the dimensional change of the inner ring was small and the press-fit state with the shaft was maintained. On the other hand, in the bearing of Comparative Example 1, since the average retained austenite amount of both the inner ring and the outer ring greatly exceeded 4% by volume, the inner diameter of the inner ring was significantly larger than the diameter of the shaft by +16 μm, and interference was lost. , The bearing was in a state where it could easily come off the shaft. As for the bearing of Comparative Example 7, the average retained austenite amount of both the inner ring and the outer ring exceeded 4% by volume, but the amount of deviation from the range of the present invention was 5% by volume. It wasn't in a state where it could be easily removed. However, as will be apparent from the life test described later, the interference was insufficient so that so-called creep would occur between the shaft and the bearing.

Regarding the internal clearance, the first and second embodiments are described.
Since the average retained austenite amount of the rolling elements of the bearings 3 and 4 was relatively small, the amount of change in the internal clearance could be stopped to about 20 μm to maintain the “plus” internal clearance. On the other hand, in the bearing of Comparative Example 2, since the average retained austenite amount of the rolling elements exceeds 30% by volume, the internal clearance greatly changes to 0 μm, which will become clear in the life test described later. As described above, the bearing is preloaded in the mounted state, which causes a problem that the bearing cannot rotate smoothly. Further, in the bearing of Comparative Example 7, the average retained austenite amount of the rolling elements is 30% by volume, which is within the range of the present invention. However, since the average retained austenite amount of both the inner ring and the outer ring exceeds 4% by volume, the internal clearance is increased. It changed greatly and became 0 μm. In the bearing of Comparative Example 1, since the average retained austenite amount of the rolling elements is small, the change amount of the internal clearance is as small as 3 μm. However, due to the average retained austenite amount of the inner ring, There is a defect.

From the above, if the average retained austenite amount of the inner ring is 4% by volume, a sufficient interference margin is maintained even after the test, the average retained austenite amount of the inner ring is 4% by volume, and the rolling element is It can be seen that, when the average retained austenite amount in (3) is 30% by volume or less, sufficient internal clearance remains. <Life test> For each of the bearings of Examples 1 to 4 and Comparative Examples 2 to 7 assembled with the combinations shown in Table 3 below, a ball bearing life tester manufactured by NSK Ltd. was used. The L ₁₀ life under lubrication with foreign matter was measured under the following conditions.

Foreign matter mixed: Cementite type particles H _v ; 540 diameter; 74 to 147 μm mixed amount; 1000 ppm Lubricating oil: Turbine oil FBK oil RO150 manufactured by Nippon Oil Co., Ltd. Load condition: P (load load) / C (dynamic load rating) ) = 0.
32 Bearing rotation speed: 4900 rpm Test temperature: 170 ° C. That is, a life test was performed on 10 bearings of each type under the above conditions, and due to the Weibull distribution function, flaking occurred on 10% of the bearings from the short life side. The total rotation time up to was determined and used as the life. The results are also shown in Table 3. In the table, “average retained austenite amount” is abbreviated as “average γ _R ”.

[0032]

[Table 3]

As can be seen from the results of Table 3, Examples 1 to 1
Each bearing of No. 4 has a long life exceeding 80 hours. On the other hand, in the bearing of Comparative Example 2, as described above, since the average retained austenite amount of the rolling elements exceeds 30% by volume which is the upper limit of the range of the present invention, the internal clearance becomes "0". Therefore, the bearing is preloaded when mounted. Therefore, as the life test time becomes longer, smoother rotation cannot be achieved, and finally the cage is damaged and the "rolling phenomenon" in which the rolling elements cannot roll.

In the bearings of Comparative Examples 3 to 6, the average retained austenite amount of the inner ring is within the range of the present invention, but the average retained austenite amount of the rolling elements is 20 vol% which is the lower limit of the range of the present invention. Since it is less than,
The “c” value (the ratio of the curvature r of the edge portion of the indentation and the radius c of the indentation generated on the surface of the raceway surface due to repeated contact with foreign matter) becomes small, and the stress concentration at the edge portion of the indentation is sufficiently relaxed. I don't know. As a result, the rolling life was shortened under high temperature and lubrication containing foreign matter.

Further, in the bearing of Comparative Example 7, since the average retained austenite amount of the inner ring exceeds 4% by volume, the dimensional change of the inner ring is large and the interference between the shaft and the shaft is insufficient. As the life test time increased, so-called creep occurred between the shaft and the bearing, and the resulting vibration increased, so the tester operation was stopped.

The above data are used to calculate the average retained austenite amount of the inner ring and the inner diameter difference after the dimensional stability test (the above-mentioned "D _N -D").
Organize the graph the relationship between the ₀ ") in FIG. 5, the relationship between the internal clearance of the rolling residual austenite amount of the moving object and the dimensional stability after the test, and measured by the amount of retained austenite and life test of rolling elements life The graphs arranged for the relationship are shown in FIG. In addition, in FIG.
"Average retained austenite amount" is abbreviated as "average γ _R ".

In FIG. 5, “◯” indicates that the average retained austenite amount of the inner ring and the rolling elements is within the range of the present invention.
In Tables 2 and 3, data regarding bearings described as “Example” are shown. “●” indicates that the average retained austenite amount of either the inner ring or the rolling element is out of the range of the present invention. It is the data regarding the bearing described as "Comparative example". Also, the shaded area indicates the area where the internal diameter difference causes problems such as creep between the bearing and the shaft during the life test, or the condition where the bearing easily comes off the shaft after the dimensional stability test. ing.

As can be seen from the graph of FIG. 5, the average retained austenite amount of the inner ring is 4% by volume, which is within the range of the present invention.
If it is below, it is apparent that the dimensional change of the inner ring is suppressed to a small level, and problems such as creep generation between the bearing and the shaft do not occur. Further, in FIG. 6, “◯” and “●” indicate data on the internal clearance after the dimensional stability test, and among them, “◯” indicates that the average retained austenite amount of the inner ring and the rolling element falls within the range of the present invention. Yes, Tables 2 and 3
Is data on bearings described as "Example" in
“” is data regarding the bearing described as “Comparative Example” in Tables 2 and 3 in which the average retained austenite amount of either the inner ring or the rolling element is out of the range of the present invention. In addition, “□” and “■” indicate the data regarding the life measured by the life test. Among these, “□” indicates that the average retained austenite amount of the inner ring and the rolling element is within the range of the present invention. Is data regarding the bearing described as “Example” in Table 1, and “■” is “Comparative Example” in Tables 2 and 3 in which the average retained austenite amount of either the inner ring or the rolling element is out of the range of the present invention. It is the data about the bearing shown.

As can be seen from the graph of FIG. 6, if the average retained austenite amount of the rolling elements is 30% by volume or less,
The decrease in internal clearance can be suppressed to a relatively small value.
Further, if the average retained austenite amount of the rolling elements is 20 to 30% by volume, which is within the range of the present invention, it is clear that the service life under high temperature and foreign matter-containing lubrication can be extended.

In the present invention, it is preferable that the alloy steel forming the inner ring, the outer ring, and the rolling elements contains Mo in a proportion of 2.00% by weight or less and Ni in a proportion of 1.00% by weight or less. That is, by containing Mo, the hardenability can be enhanced and the toughness can be increased, but if the content exceeds 2.00% by weight, the grain size of the carbide generated in the surface layer portion becomes large. Further, by containing Ni, the quenched structure can be homogenized and the impact resistance can be improved, but it is uneconomical to contain Ni in an amount exceeding 1.00% by weight, and C, Si, Mn, Cr It is more economical to increase the amount. Mo and Ni contained for such purposes
Content of 0.08% by weight or more,
A predetermined effect is exhibited by containing 0.08% by weight or more, and the above-mentioned effects can be enhanced by increasing the content below the respective upper limit values.

Further, in the rolling bearing of the present invention, the amount of retained austenite in the surface layer portion of the rolling element is 20 to 4
When the content is 5% by volume, the life under lubrication with foreign matter becomes long, which is preferable. The surface layer here is calculated from the contact pressure applied to the contact surface of the raceway surface, and assuming that the maximum shear stress position (depth from the surface) is Z ₀ , Z _{0 to} 2Z from the surface. The part up to a depth of ₀ , eg
It refers to a depth of about 0.2 to 0.5 mm from the surface.

Further, in the above embodiment, the content ratio of C is 0.
Steel A, which is less than 80% by weight, is carbonitrided, then quenched and tempered. However, instead of carbonitriding, carburizing (for example, at 920 to 950 ° C for 3 hours) is performed. Hardening and tempering may be performed. Further, in the above-mentioned embodiment, the rolling bearing having the balls as the rolling elements is described, but it goes without saying that the rolling bearing of the present invention is not limited to the ball bearing and is also applied to various roller bearings. .

[0043]

As described above, according to the present invention, good dimensional stability and long rolling life can be obtained under the conditions of high temperature and foreign matter mixed in the lubricant in the bearing. It is possible to provide a rolling bearing that can hold both of these.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining an operation of the present invention.

FIG. 2 is a graph showing the conditions of carbonitriding, quenching, and high-temperature tempering performed on steel A in the examples, where (a) is carbonitriding, (b) is quenching, and (c) is It corresponds to the condition of high temperature tempering.

FIG. 3 is a graph showing the conditions of quenching and tempering applied to steel B in the example, (b) of FIG.
(C) corresponds to high temperature tempering conditions.

FIG. 4 shows carbonitriding, quenching,
It is a graph which shows the distribution of the amount of retained austenite in the inner ring obtained by high temperature tempering.

FIG. 5 is a graph summarizing the relationship between the average retained austenite amount of the inner ring and the inner diameter difference after the dimensional stability test, regarding the data in the examples.

FIG. 6 shows the relationship between the retained austenite amount of rolling elements and the internal clearance after the dimensional stability test, and the relationship between the retained austenite amount of rolling elements and the life measured by the life test. It is a graph.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F16C 33/32 F16C 33/32 (56) References JP-A-5-118336 (JP, A) JP-A-4-26752 (JP , A) JP 63-308219 (JP, A) JP 4-333558 (JP, A) JP 5-271779 (JP, A) JP 64-55423 (JP, A) JP 3-153842 (JP, A) JP-A-3-82736 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16C 33/30-33/64 C21D 9/40 C22C 38 / 00 C22C 38/18 C23C 8/32

Claims (5)

(57) [Claims] 1. A inner ring made of alloy steel, the outer ring, and rolling elements, hardened after being carburized or carbonitrided, or formed by tempering, or quenching, in a rolling bearing formed by tempering, the alloy Steel contains 0.10 to 1.00 wt% C, 0.50 to 3.00 wt% Cr, and 0.15 to 1.00 Si.
% Of Mn and 0.20 to 1.50% by weight of Mn, the balance being Fe and inevitably mixed impurities, and the average residual austenite amount of at least the inner ring of the inner ring and the outer ring. Of 4% by volume or less and the average retained austenite amount of the rolling element is 20 to 30% by volume.
Rolling bearings characterized by 2. The C content of the alloy steel forming the inner ring is 0.
The rolling shaft according to claim 1, which is 10 to 0.80% by weight.
Receiving. 3. The C content of the alloy steel forming the rolling element is
The rolling according to claim 1, which is 0.80 to 1.00% by weight.
bearing. 4. The alloy steel contains Mo in an amount of 2.0% by weight or less.
Below, Ni is contained in each proportion of 1.0% by weight or less.
The rolling bearing according to any one of 1 to 3. 5. The amount of retained austenite in the surface layer of the rolling element
Is 20 to 45% by volume.
Rolling bearing described in.