JP5597977B2 - Bearing component, method for manufacturing the same, and rolling bearing - Google Patents

Description

  The present invention relates to a bearing component, a method for manufacturing the same, and a rolling bearing.

Rolling bearings are localized at the contact area between each raceway surface of the outer and inner rings and the rolling element when subjected to an excessive static load during use or a large impact load during rotation at an extremely low rotational speed. May cause permanent deformation. This permanent deformation becomes larger as the load increases, and when the limit load (static load rating) is exceeded, smooth rotation is hindered. For example, in the case of a ball bearing, the maximum contact stress between the rolling elements and the race of the outer inner ring is about 4200 MPa, and the static load rating is determined in consideration of such stress when designing the ball bearing. It has been.
The improvement of the static load rating is one of the important issues in order to realize a reduction in the size and weight of the rolling bearing.

  On the other hand, when the rolling bearing receives a load and rotates, a repeated stress is applied to each raceway surface of the outer inner ring and the rolling surface of the rolling element. For this reason, if it continues to be used for a certain period of time, rolling fatigue occurs in the material of the bearing component constituting the rolling bearing, and flaking occurs on the raceway surface and the rolling surface. The total number of rolling bearing rotations (referred to as “rolling fatigue life”) until flaking occurs on the raceway surface and rolling surface is an index for replacing the rolling bearing, and the longer this rolling fatigue life is, The frequency of replacing the rolling bearing can be reduced.

As a rolling bearing with improved rolling fatigue life, for example, a material formed into a predetermined shape by machining a high carbon chromium bearing steel such as JIS SUJ2 into a predetermined shape, carburized with a carbon potential of 1.2 or more. Carburizing treatment is performed in an atmosphere at 840 to 870 ° C. for 3 hours or more, rapidly cooling, and further tempering treatment, so that the total carbon content of the surface layer in the range from the surface to the depth at which the maximum shear stress acts can be obtained. The amount of solid solution carbon in the matrix of the surface layer within the range of 0.5 mm from the surface is 0.6 to 1.0% by mass, and a carbon compound is formed in the surface layer. There are known rolling bearings having outer and inner rings in which the amount of the carbon compound deposited is 5 to 15% in terms of area ratio and the particle size of the carbon compound particles is 3 μm or less (see Patent Document 1). Irradiation).
However, from the viewpoint of miniaturization of parts, there are many applications in harsh usage environments such as increased loads on outer and inner rings and rolling elements, and higher operating temperatures, and further higher performance is required. ing.

In addition, for example, when the rolling bearing is used under a foreign matter mixed condition, the foreign matter may be pressed against the outer inner ring or the rolling element, and an indentation may be formed on the raceway surface of the outer inner ring or the surface of the rolling element. A surface damage portion such as an indentation generated by such a foreign matter becomes a starting point of fatigue peeling due to stress concentration, and is one of the causes of reducing the life of the rolling bearing.
Therefore, there is a demand for an improvement in the life of the rolling bearing under the foreign matter mixing condition.

  In order to improve the life of rolling bearings, for example, machining to steel materials containing 3.2 to 5.0 mass% chromium, less than 1.0 mass% molybdenum, less than 0.5 mass% vanadium, etc. Is subjected to a carburizing treatment that is heated at 850 to 930 ° C. in a carburizing atmosphere having a carbon potential of 1.2 to 1.5 and rapidly cooled, By performing the tempering treatment, the average particle size of carbide particles in the surface layer portion of the bearing component of the rolling bearing is 0.5 μm or less, the area ratio of the particles of carbide is 9 to 30%, and Rockwell C hardness It is proposed that the thickness is 63 (Vickers hardness 770) or more, and the amount of retained austenite in the surface layer portion is 30 to 50% by volume (see Patent Document 2).

Japanese Patent Laid-Open No. 2004-52101 JP 2006-176863 A

When the amount of retained austenite on the surfaces of the outer and inner rings and rolling elements is increased as in the method described in Patent Document 2, stress concentration around the indentation generated when a foreign object is bitten can be reduced. Therefore, the life in foreign oil can be improved and the life of the rolling bearing can be extended.
However, since the yield stress of retained austenite is significantly lower than that of martensite, the static load capacity is lowered.

  In contrast, it is conceivable to improve the static load capacity by reducing the amount of retained austenite on the surfaces of the outer and inner rings and rolling elements, but the amount of retained austenite on the surfaces of the outer and inner rings and rolling elements has been reduced. In such a case, it is considered that a sufficient life cannot be ensured.

  The present invention has been made in view of such circumstances, and provides a bearing component member capable of extending the life of a rolling bearing and ensuring a sufficient static load capacity, and a method for manufacturing the same. The purpose is to provide. Another object of the present invention is to provide a rolling bearing that has a long life and exhibits a sufficient static load capacity.

The bearing component according to the present invention is obtained by processing a steel containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium, In a carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume, the carbonitriding process is performed by heating and quenching at 850 to 900 ° C. A bearing component having a surface that is obtained by performing sub-zero treatment at −50 to −100 ° C. and finishing, and has a polished finish,
The content of carbon in the surface layer in the range from the polished surface to 10 μm is 1.1 to 1.6 mass%, and the Vickers hardness at a depth of 50 μm from the surface is 800 to 940, the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, and the nitrogen content in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0. Mass%,
The surface layer in the range from the surface to 10 μm has particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and / or particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride. and if both the particle size 0.2~2μm of particles consisting of particles and vanadium carbonitride particle size 0.2~2μm consisting vanadium nitride on the surface layer is present, the The total area ratio of particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride in the surface layer is 1 to 10%, and the surface layer When either one of particles having a particle size of 0.2 to 2 μm made of vanadium nitride and particles having a particle size of 0.2 to 2 μm made of vanadium carbonitride is present, the particle size of vanadium nitride is 0. .2 to 2 μm particles and It is characterized in that the area ratio of particles present in the surface layer of the particle size 0.2~2μm of particles consisting of vanadium carbonitrides are 1-10%. The surface layer in the range from the surface to 10 μm is defined as the range between the surface and a position at a depth of 10 μm from the surface.

The bearing constituent member of the present invention is obtained by subjecting the intermediate material subjected to the carbonitriding process to the sub-zero treatment. As a result, in the bearing component of the present invention, the Vickers hardness at a depth of 50 μm from the polished surface is 800 to 940 (Rockwell C hardness 64 to 68), and 10 μm from the surface. The amount of retained austenite at the depth position is 5 to 30% by volume.
Therefore, in the bearing component of the present invention, the amount of martensite is large, the yield stress is high, and a sufficient static load capacity is ensured. Thus, according to the bearing component of the present invention, each of the outer and inner rings can be used even when receiving an excessive static load during use or when receiving a large impact load during rotation at an extremely low rotational speed. The amount of local permanent deformation at the contact portion between the raceway surface and the rolling element can be reduced.

In the present invention, the bearing component member is a race member having a raceway portion that is polished and finished, and the steel material contains 0.7 to 0.9% by mass of carbon and exists in a portion other than the raceway portion. The Vickers hardness at a position where the carbon content in the surface layer in the range from the surface of the non-polished part to 10 μm is 0.7 to 1.0% by mass and at a depth of 50 μm from the surface of the non-polished part. Is preferably 700 to 800.
In this case, the carbon content in the surface layer in the range from the surface of the non-polishing part existing in the portion other than the track part to 10 μm is 0.7 to 1.0% by mass, and the surface of the non-polishing part Since the Vickers hardness at a depth of 50 μm is 700 to 800, generation of excessive carburized structure in the non-polished part can be suppressed.
Therefore, the track member as a bearing component having such a configuration is subject to external loads in addition to the above-described effects. For example, when used as an outer ring of a rolling bearing, the rolling fatigue life of the rolling bearing is improved. And sufficient strength can be given to the rolling bearing.

A rolling bearing according to the present invention is a rolling bearing having an outer ring having a raceway portion on an inner peripheral surface, an inner ring having a raceway portion on an outer peripheral surface, and a plurality of rolling elements disposed between both raceway portions of the outer inner ring. A bearing,
The outer ring is a fixed ring and is made of the above-described bearing component.

  In the rolling bearing according to the present invention, since the outer ring as the fixed ring is made of the above-described bearing constituent member, the static bearing capacity in the fixed ring where the maximum contact stress is maximized is sufficiently ensured in the rolling bearing. Thereby, according to the rolling bearing of the present invention, it is possible to reduce the amount of permanent deformation at the contact portion with the rolling element in the outer ring which is a fixed ring, and even if the static load or impact load exceeds the limit load, Smooth rotation can be ensured.

In the rolling bearing of the present invention, the inner ring is a drive wheel, and is obtained from a steel material containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium. The carbon content in the surface layer in the range from the surface to 10 μm is 1.1 to 1.6% by mass, and the Vickers hardness at a depth of 50 μm from the surface is 740 to 900 (Rockwell C The hardness is 62 to 67), the amount of retained austenite at a depth of 10 μm from the surface is 20 to 55% by volume, and the nitrogen content in the surface layer in the range from the surface to 10 μm is 0.1. In the surface layer in the range from 1.0 to 10% by mass and from the surface to 10 μm, particles having a particle diameter of 0.2 to 2 μm and / or a particle diameter of 0.2 to 0.2 μm made of vanadium carbonitride are used. It has 2μm particles And if both the particle size 0.2~2μm of particles consisting of particles and vanadium carbonitride particle size 0.2~2μm consisting vanadium nitride on the surface layer is present, the surface The total area ratio of particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride in the layer is 1 to 10%, When either one of a particle having a particle size of 0.2 to 2 μm made of vanadium nitride and a particle having a particle size of 0.2 to 2 μm made of vanadium carbonitride is present, the particle size of vanadium nitride is 0. Of the particles having a particle diameter of 0.2 to 2 μm made of 2-2 μm particles and vanadium carbonitride, it is preferable that the particles have an area ratio of 1 to 10%.
As described above, the rolling bearing of the present invention has a retained austenite amount of 20 to 55% by volume at a depth of 10 μm from the surface of the inner ring. Even if it is used, the stress concentration around the indentation generated when the rolling bearing bites in the foreign matter is relieved, and the surface origin damage is suppressed. Therefore, in this case, a high life in foreign oil can be ensured.

The method for producing a bearing component according to the present invention processes a steel material containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium into a predetermined shape. And a pre-processing step to obtain a shaped material,
Carburizing by heating the base material at 850 to 900 ° C. in a carbonitriding atmosphere having a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume with respect to the base material. Carburizing and nitriding process to obtain nitriding and intermediate material,
By subjecting the intermediate material after the carbonitriding process to a subzero treatment process for performing a subzero treatment for cooling the intermediate material at −50 to −100 ° C., and applying a finishing process to the intermediate material after the subzero treatment process The Vickers hardness at a position 50 μm deep from the surface is 800 to 940 (Rockwell C hardness 64 to 68), and the amount of retained austenite at a position 10 μm deep from the surface is 5 to 30% by volume. The content of nitrogen in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0% by mass, and in the surface layer in the range from the surface to 10 μm, the particles made of vanadium nitride has a particle size 0.2 to 2 .mu.m particles consisting of particles and / or vanadium carbonitrides of diameter 0.2 to 2 .mu.m, and particle size 0 consisting of vanadium nitride on the surface layer When both particle size 0.2~2μm of particles consisting of particles and vanadium carbonitride .2~2μm is present, the particle size 0.2~2μm consisting of vanadium nitride in the surface layer Particles having a particle size of 0.2 to 2 [mu] m made of vanadium nitride on the surface layer. And any one of particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and a particle diameter made of vanadium carbonitride It includes a finishing step for obtaining a bearing component having an area ratio of particles of 1 to 10% in the surface layer among particles of 0.2 to 2 μm .

In the method for manufacturing a bearing component according to the present invention, the carbon steel obtained from the steel material is subjected to the carbonitriding process, the intermediate material after the carbonitriding process is further subjected to subzero treatment, and the subzero treatment is performed. Since the intermediate material is finished, the retained austenite on the surface of the intermediate material after carbonitriding can be changed to harder martensite.
Therefore, the Vickers hardness at a position 50 μm deep from the surface is 800 to 940 (Rockwell C hardness 64 to 68), the amount of retained austenite at a position 10 μm deep from the surface is 5 to 30% by volume, The content of nitrogen in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0% by mass, and the particle size in the surface layer in the range from the surface to 10 μm is vanadium nitride is 0.2 to 2 μm. particles and / or particle size 0.2~2μm of particles consisting of vanadium carbonitrides in the presence of, and particles having a particle size 0.2~2μm consisting vanadium nitride on the surface layer and vanadium carbonitride In the case where both particles having a particle diameter of 0.2 to 2 μm are present, a particle having a particle diameter of 0.2 to 2 μm composed of vanadium nitride and a particle diameter of vanadium carbonitride in the surface layer is 0. 2 The total area ratio with 2 μm particles is 1 to 10%, and the surface layer has a particle size of 0.2 to 2 μm made of vanadium nitride and a particle of 0.2 to 2 μm particle size made of vanadium carbonitride. Is present in the surface layer among particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride. The area ratio of the particles can be 1 to 10%.
Therefore, the bearing structural member obtained by the manufacturing method employing such a configuration can exhibit the effects of the above-described bearing structural member when used as a fixed ring in a rolling bearing.

The method for manufacturing a race member of the present invention is a method for producing a race member as the bearing component described above,
A steel material containing 0.7 to 0.9 mass% carbon, 3.2 to 5.0 mass% chromium, and 0.05 mass% or more and less than 0.5 mass% vanadium is formed into a predetermined shape. Processing to obtain a track member shape material having a grinding allowance in at least a portion forming the raceway surface,
In a carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume, the raw material is heated at 850 to 900 ° C. for 4 hours or more. Carbonitriding process to obtain intermediate material by performing carbonitriding to quench
A sub-zero treatment step for subjecting the intermediate material after carbonitriding to a sub-zero treatment for cooling the intermediate material at −50 to −100 ° C., and a portion for forming the raceway surface of the intermediate material after the sub-zero treatment step In addition, the track portion is formed by polishing finishing, and the carbon content in the surface layer in the range from the surface of the track portion to 10 μm is 1.1% by mass or more and less than 1.6% by mass. The Vickers hardness at a depth of 50 μm from the surface is 800 to 940, the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, and from the surface to 10 μm The content of nitrogen in the surface layer in the range of 0.1 to 1.0% by mass and the surface layer in the range from the surface to 10 μm has a particle diameter of 0.2 to 2 μm made of vanadium nitride. Particles of the child and / or consisting of vanadium carbonitrides have a particle diameter 0.2 to 2 .mu.m, and particle size 0.2 to 2 .mu.m consisting vanadium nitride on the surface layer and vanadium When both particles having a particle size of 0.2 to 2 μm made of carbonitride are present , particles having a particle size of 0.2 to 2 μm made of vanadium nitride and a particle size made of vanadium carbonitride in the surface layer The total area ratio with 0.2 to 2 μm particles is 1 to 10%, and the surface layer has a particle size of 0.2 to 2 μm made of vanadium nitride and a particle size of vanadium carbonitride of 0. When any one of the particles having a particle size of 2 to 2 μm is present, the particles among the particles having a particle size of 0.2 to 2 μm made of vanadium nitride and the particles having a particle size of 0.2 to 2 μm made of vanadium carbonitride are used. surface of the particles present in the surface layer The rate is 1 to 10%, the carbon content in the surface layer in the range from the surface of the non-polished part existing in the part other than the track part to 10 μm is 0.7 to 1.0% by mass, and It includes a finishing step of obtaining a raceway member having a Vickers hardness of 700 to 800 at a position of a depth of 50 μm from the surface of the non-polished part.

According to the manufacturing method of the race member adopting such a configuration, with respect to the shape member of the race member having a grinding allowance in at least a portion forming the raceway surface obtained by processing the steel material into a predetermined shape, The surface of the part that forms the raceway surface of the intermediate material after carbonitriding because carbonitriding is performed, the intermediate material after carbonitriding is subjected to subzero treatment, and the intermediate material after such subzero treatment is finished. The retained austenite in can be changed to harder martensite.
Therefore, the Vickers hardness at a position where the carbon content in the surface layer in the range from the surface of the raceway portion of the raceway member to 10 μm is 1.1% by mass or more and less than 1.6% by mass and 50 μm deep from the surface. 800 to 940, the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, and the nitrogen content in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0 mass. %, In the surface layer in the range from the surface to 10 μm, particles having a particle diameter of 0.2 to 2 μm and / or particles of vanadium carbonitride consisting of vanadium nitride are present. and if both the particle size 0.2~2μm of particles consisting of particles and vanadium carbonitride particle size 0.2~2μm consisting vanadium nitride on the surface layer is present, the surface In layers The total area ratio of particles having a particle diameter of 0.2 to 2 μm made of nadium nitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride is 1 to 10%, and vanadium nitride is formed on the surface layer. When any one of particles having a particle diameter of 0.2 to 2 μm and particles of vanadium carbonitride having a particle diameter of 0.2 to 2 μm is present, the particle diameter of vanadium nitride being 0.2 to 2 μm Non-polishing part existing in a part other than the orbital part, with the area ratio of the particles existing in the surface layer among the particles of 0.2 to 2 μm in diameter composed of the above particles and vanadium carbonitride being 1-10% The carbon content in the surface layer in the range from 10 μm to 10 μm is 0.7 to 1.0% by mass, and the Vickers hardness at a depth of 50 μm from this surface is 700 to 800. Can do.
Therefore, the bearing constituent member obtained by the manufacturing method employing such a configuration can exhibit the above-described effects.

  According to the bearing component and the manufacturing method thereof of the present invention, it is possible to extend the life of the rolling bearing and to achieve an excellent effect that a sufficient static load capacity can be secured. In addition, the rolling bearing of the present invention has an excellent effect that it has a long life and exhibits a sufficient static load capacity.

It is a schematic explanatory drawing which shows the ball bearing as a rolling bearing which has a bearing structural member which concerns on one Embodiment of this invention. It is process drawing which shows the manufacturing method of the outer ring | wheel which is a bearing structural member which concerns on one Embodiment of this invention. It is a diagram which shows the heat processing conditions in the experiment number 1. FIG. It is a diagram which shows the heat processing conditions in the experiment number 2. FIG. It is a diagram which shows the heat processing conditions in the experiment number 3. FIG. It is a diagram which shows the heat processing conditions in the experiment number 4. FIG. It is a diagram which shows the heat processing conditions in the experiment number 5. FIG. It is a diagram which shows the heat processing conditions in the experiment number 6 and the comparative example 8. FIG. It is a diagram which shows the heat processing conditions in the experiment number 7. FIG. It is a diagram which shows the heat processing conditions in the experiment number 8. FIG. It is a diagram which shows the heat processing conditions in the experiment number 9. FIG. It is a diagram which shows the heat processing conditions in the experiment number 10. FIG. It is a diagram which shows the heat processing conditions in the experiment number 11. FIG. It is a diagram which shows the heat processing conditions in the experiment number 12. FIG. It is a diagram which shows the heat processing conditions in the experiment number 13. FIG. 6 is a diagram showing heat treatment conditions in Example 3. FIG. It is a diagram which shows the heat processing conditions in the comparative example 9. It is a diagram which shows the heat processing conditions in the comparative example 10. It is a diagram which shows the heat processing conditions in the comparative example 11. It is a diagram which shows the heat processing conditions in the comparative example 12.

[Bearing components and rolling bearings including the same]
Hereinafter, an outer ring which is a bearing constituent member according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view showing the structure of a ball bearing as a rolling bearing provided with a bearing component (outer ring) according to an embodiment of the present invention.

  The ball bearing 60 includes an outer ring 51 having a raceway portion 51a on an inner peripheral surface, an inner ring 52 having a raceway portion 52a on an outer peripheral surface, and a plurality of raceways disposed between both raceway portions 51a and 52a. A ball 53 as a rolling element and a retainer 54 that holds a plurality of balls 53 at predetermined intervals in the circumferential direction are provided.

The surfaces of the raceway portion 51a, the end surface 51b, the shoulder surface 51c, and the outer peripheral surface 51d of the outer ring 51 are polished portions that are polished.
On the other hand, a chamfer 51e on the outer peripheral side of the outer ring 51 having an R-shaped cross section connected to the end surface 51b and the outer peripheral surface 51d of the outer ring 51, and a chamfer 51f on the inner peripheral side of the outer ring 51 having a linear cross section connected to the end surface 51b and the shoulder surface 51c. Is configured as a non-polishing part that has not been polished.
Further, the surfaces of the raceway portion 52a, the end surface 52b, the shoulder surface 52c, and the inner peripheral surface 52d of the inner ring 52 are polished portions that are polished. On the other hand, a chamfer 52e on the inner peripheral side of the inner ring 52 having an R-shaped cross section connected to the end surface 52b and the inner peripheral surface 52d of the inner ring 52, and a chamfer on the outer peripheral side of the inner ring 52 having a linear cross section connected to the end surface 52b and the shoulder surface 52c. 52f is configured as a non-polishing portion that has not been polished.

In the ball bearing 60, the outer ring 51 is a fixed ring, and the inner ring 52 is a drive wheel.
And the curvature radius of the rolling surface of the track part 52a in the inner ring 52 is 0.505Bd, when the diameter of the ball 53 is Bd, and the curvature radius of the rolling surface of the track part 51a in the outer ring 51 is 0.53Bd. It is. As described above, in the ball bearing 60, the radius of curvature of the outer ring 51 is larger than the radius of curvature of the inner ring 52. Therefore, the maximum contact stress between the outer ring 51 and the ball 53 is increased between the inner ring 52 and the ball 53. It is larger than the maximum contact stress between.
Therefore, the outer ring 51 has a higher static load capacity by reducing the amount of retained austenite than the inner ring 52. Thereby, in the outer ring | wheel 51, suppression of generation | occurrence | production of a permanent deformation is achieved.
On the other hand, in the inner ring 52, the amount of retained austenite is increased as compared with the outer ring 51, so that stress concentration around the indentation generated when a foreign object is bitten is alleviated. Thereby, in the inner ring | wheel 52, the lifetime in a foreign material oil is improved.

  The outer and inner rings 51 and 52 are each made of a member obtained from a steel material containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium.

In the outer ring 51 that is a fixed ring, the amount of retained austenite at a depth of 10 μm from the surface of the polishing part including the track part 51 a is 5 to 30% by volume, and the polishing part including the track part 52 a of the inner ring 52. The amount of retained austenite is less than that of. Thereby, since the amount of martensite is large in the outer ring 51, the yield stress is high and a sufficient static load capacity is secured.
As described above, in the outer ring 51, the amount of retained austenite at a position 10 μm deep from the surface of the polishing part including the raceway part 51a is set to 5% by volume or more, so that sufficient life performance as an outer ring is ensured. ing. Further, since the amount of retained austenite at a depth of 10 μm from the surface of the track part 51a is 30% by volume or less, a sufficient static load capacity is secured as an outer ring.
Therefore, even when the load of the maximum contact stress in the ball bearing 60 becomes the largest, since the sufficient static load capacity is secured in the outer ring 51 which is a fixed ring, each raceway surface of the outer inner ring and the rolling element The amount of permanent deformation at the contact portion can be reduced, and smooth rotation can be maintained.

  In the outer ring 51, the hardness at a depth of 50 μm from the surface of the polishing part including the raceway part 51 a has a Vickers hardness of 800 (Rockwell C) from the viewpoint of securing a sufficient life and static load capacity as the outer ring. The hardness is 64) or more, and is Vickers hardness 940 (Rockwell C hardness 68) or less from the viewpoint of suppressing embrittlement and ensuring sufficient toughness as a bearing.

  In one embodiment, the surface layer in the range from the surface of the polishing portion including the track portion 51a to 10 μm may have particles (nitride particles) made of nitride having a particle size of 500 nm or less, The area ratio of the precipitate containing nitride in the surface layer may be 5 to 20%. In this case, generation of excess carburized structure is suppressed, and sufficient crushing strength can be obtained.

  In one embodiment, the area ratio of the precipitate containing nitride in the surface layer in the range from the surface of the polishing portion including the track portion 51a to 10 μm is preferably 5% or more from the viewpoint of obtaining sufficient crushing strength. From the viewpoint of preventing embrittlement due to excessive nitriding, 20% or less is preferable.

  In one embodiment, the carbon content in the surface layer in the range from the surface of the non-polished part including the chamfer 51e on the outer peripheral side of the outer ring 51 and the chamfer 51f on the inner peripheral side of the outer ring 51 to 10 μm is From the viewpoint of obtaining hardness for securing static strength as 0.7% by mass or more, from the viewpoint of obtaining sufficient crushing strength by suppressing the occurrence of excessive carburized structure in the non-polished part, 1 0.0 mass% or less.

  In one embodiment, the Vickers hardness at a depth of 50 μm from the surface of the non-polished part including the chamfer 51e on the outer peripheral side of the outer ring 51 and the chamfer 51f on the inner peripheral side of the outer ring 51 is a ball bearing. From the viewpoint of obtaining sufficient strength, it is 700 or more, and from the viewpoint of ensuring sufficient toughness, it is 800 or less.

  On the other hand, in the inner ring 52 that is a driving wheel, the amount of retained austenite at a depth of 10 μm from the surface of the polishing portion including the raceway portion 52a is determined when the ball bearing 60 is used in the lubricating oil mixed with foreign matter. From the viewpoint of relaxing the stress concentration around the indentation generated when the foreign matter is bitten, it is 20% by volume or more, and from the viewpoint of obtaining sufficient surface hardness as the inner ring, it is 55% by volume or less.

Further, in the inner ring 52, since the Vickers hardness at a position 50 μm deep from the surface of the polishing part including the raceway part 52a is 740 (Rockwell C hardness is 62) or more, foreign matter is mixed in. When the ball bearing 60 is used in the lubricating oil, the size of the impression generated when the foreign matter is caught can be reduced. Furthermore, the inner ring 52 has a Vickers hardness of 900 (Rockwell C hardness of 67) or less at a depth of 50 μm from the surface of the polishing part including the raceway part 52a, thereby preventing embrittlement. can do.
The Vickers hardness at a depth of 50 μm from the surface is obtained by cutting the outer ring 51 a and the inner ring 52 in the depth direction from the surface and then applying a Vickers indenter at a depth of 50 μm from the surface. It is a measured value. The Rockwell C hardness is a value obtained by converting the measured Vickers hardness.

There are particles made of vanadium nitride and / or particles made of vanadium carbonitride in the surface layer in a range of 10 μm from the surface of each of the polishing portion and the ball 53 including the raceway portions 51a, 52a of the outer inner rings 51, 52. doing. The particle size of the particles is 0.2 μm or more from the viewpoint of improving yield stress by dispersion strengthening by the Orowan mechanism, and preferably 2 μm or less from the viewpoint of inducing coarsening of the particles by Ostwald growth. Note that the surface layer in the range from the surface of the polishing portion to 10 μm also includes particles having a particle size of less than 0.2 μm.
Further, cementite, M ₇ C ₃ type carbide, and M ₂₃ C ₆ type carbide are deposited on the surfaces of the polishing portion including the raceway portions 51 a and 52 a of the outer inner rings 51 and 52 and the balls 53.

  Particles having a particle diameter of 0.2 to 2 μm and / or vanadium charcoal made of the vanadium nitride in the surface layer in a range of 10 μm from the surface of each of the polishing part and the ball 53 including the raceway parts 51 a and 52 a of the outer inner rings 51 and 52 From the viewpoint of ensuring a sufficient static load capacity for each of the fixed wheel and the drive wheel by improving the yield stress by dispersion strengthening by the Orowan mechanism, the area ratio of the particles having a particle diameter of 0.2 to 2 μm made of nitride is Rockwell C hardness (or Vickers hardness) at a depth of 50 μm from the surface by suppressing excessive nitrogen intrusion into the steel material and ensuring the required amount of carbon. Is a predetermined value corresponding to each of the fixed wheel and the drive wheel, and is 10% or less from the viewpoint of securing a sufficient static load capacity for each of the fixed wheel and the drive wheel. In the present specification, the area ratio of the particles means the particle size of 0.2 to 2 μm composed of vanadium nitride and vanadium carbonitride in the surface layer in the range from the surface to 10 μm. The area ratio of the particles combined with 2 to 2 μm particles.

  The carbon content in the polishing layer including the raceway portions 51a and 52a of the outer inner rings 51 and 52 and the surface layer in the range of 10 μm from the surface of each ball 53 is effective in reducing the stress concentration on the surface damaged portion such as indentation. From the viewpoint of setting a certain amount of retained austenite to a predetermined value according to each of the fixed wheel and the driving wheel and a predetermined surface hardness according to each of the fixed wheel and the driving wheel, the surface layer is 1.1% by mass or more. From the viewpoint of further improving the life by reducing the abundance of coarse precipitates of carbides (for example, precipitates having a particle size exceeding 10 μm), the content is 1.6% by mass or less.

  The nitrogen content in the polishing layer including the raceway portions 51a, 52a of the outer inner rings 51, 52 and the surface layer in the range from the surface of each ball 53 to 10 μm is sufficient to improve the yield stress by dispersion strengthening by the Orowan mechanism. From the viewpoint of securing a sufficient static load capacity, it is 0.1% by mass or more, and by suppressing the ingress of excessive nitrogen into the steel material and ensuring the required amount of carbon, the depth of 50 μm from the surface The Vickers hardness (or Rockwell C hardness) and the retained austenite amount at the position are set to predetermined values according to the fixed wheel and the driving wheel, respectively, and the service life is extended. From the viewpoint of securing the load capacity, it is 1.0% by mass or less.

  The ball 53 which is a rolling element may be a general rolling element made of a member made of JIS SUJ2. Further, the ball 53 may be composed of a bearing constituent member similar to the outer ring 51.

  In the ball bearing 60 according to this embodiment, the outer ring 51 is a fixed wheel and the inner ring 52 is a drive wheel. However, in the present invention, the inner ring 52 is a fixed wheel and the outer ring 51 is a drive wheel. May be. In this case, as the inner ring 52 which is a fixed ring, the content of carbon in the surface layer in the range from the surface to 10 μm is 1.1 to 1.6% by mass and the depth is 50 μm from the surface as the polished portion. Vickers hardness at 800 to 940 (Rockwell C hardness is 64 to 68), the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, from the surface to 10 μm In the surface layer in the range of 0.1 to 1.0% by mass, the surface layer in the range from the surface to 10 μm has a particle diameter of 0.2 to 2 μm made of vanadium nitride. And / or particles having a particle size of 0.2 to 2 μm made of vanadium carbonitride and having a particle size of 0.2 to 2 μm made of the vanadium nitride in the surface layer in the range from the surface to 10 μm. The area ratio of the particles and / or vanadium carbonitrides diameter 0.2~2μm of particles consisting of the can bearing part is 1-10% is used.

In addition, the outer ring | wheel 51 can be manufactured with the manufacturing method of the bearing structural member concerning one Embodiment of this invention mentioned later.
Further, the inner ring 52 is, for example, a shaped material obtained by processing a steel material containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium into a predetermined shape. In a carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume, the raw material is heated at 850 to 900 ° C. and rapidly cooled. It is obtained by performing a tempering treatment that is heated at 160 ° C. or higher, and then performing a finishing process.

[Production method of bearing components]
Next, a method for manufacturing the outer ring will be described as an example of a method for manufacturing the bearing constituent member. FIG. 2 is a process diagram of a method for manufacturing a bearing component (outer ring) according to an embodiment of the present invention.

  First, an annular material 63 of an outer ring made of a steel material containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium (see FIG. 2 (a)). The manufactured and obtained annular material 63 is subjected to cutting or the like, processed into a predetermined shape, and has a grinding allowance in the portions forming the raceway surface 61a, the end surface 61b, the shoulder surface 61c, and the outer peripheral surface 61d, A chamfer 61e on the outer peripheral side of the outer ring having an R shape that is not polished and connected to the end surface 61b and the outer peripheral surface 61d, and a chamfer 61f on the inner peripheral side of the outer ring having a straight shape that is not polished and connected to the end surface 61b and the shoulder surface 61c. An outer ring shaped material 64 is obtained ["Pre-processing step", see FIG. 2 (b)].

As said steel materials, 0.7-0.9 mass% carbon, 0.05-0.70 mass% silicon, 0.05-0.7 mass% manganese, 3.2-5. A steel material containing 0% by mass of chromium, 0.1-1.0% by mass of molybdenum, 0.05% by mass or more and less than 0.5% by mass of vanadium, with the balance being iron and inevitable impurities is used. be able to.
According to such a steel material, the amount of coarse eutectic carbide precipitated at the time of manufacturing on the surface of the outer ring 61 can be reduced, fatigue fatigue at the bearing can be suppressed, and after quenching and after carbonitriding and tempering. Sufficient hardness can be ensured.

In the steel material, carbon is an element for increasing the hardness of the steel material and obtaining the internal hardness for securing the strength when performing the carbonitriding process of the next step. In addition, before carbonitriding, which will be described later, carbon is left in a large amount of undissolved carbides in the steel material, and after it is carbonitrided, it remains in a fine and large amount, thereby reducing the rolling fatigue life. It is an element that makes it possible to improve.
The content of carbon contained in the steel material is 0.7% by mass or more from the viewpoint of sufficiently leaving undissolved carbides in the steel material, and sufficient workability before carbonitriding is obtained. From the viewpoint of suppressing the formation of coarse eutectic carbides that are likely to be the starting point of fatigue failure during steel production, the content is 0.9% by mass or less.

Further, in the steel material, chromium generates a large amount of undissolved carbides that act as precipitation nuclei during the carbonitriding process before the carbonitriding process, and fine carbides (M ₇ C ₃ type carbide, M ₂₃ C ₆ type carbide), fine carbonitride [M ₇ (C, N) ₃ type carbonitride, M ₂₃ (C, N) ₆ type carbonitride] and fine nitride ( CrN, VN) is an element for improving the rolling fatigue life of the bearing component and improving the resistance to temper softening in the tempering process described later. Chromium promotes the nitriding reaction in the outermost surface layer of the steel material by promoting the formation of carbonitrides and nitrides in the steel material, and suppresses the carburizing reaction (suppresses the occurrence of excessive carburized structure).
From the viewpoint of obtaining the above effect, the content of chromium contained in the steel material is 3.2% by mass or more, and the viewpoint and cost of easily suppressing the formation of eutectic carbide that becomes the starting point of fatigue fracture are reduced. From a viewpoint of reducing, it is 5.0 mass% or less.

  In the steel material, vanadium is an element that has a very strong affinity for carbon, and is an element that forms carbide. In addition, since vanadium carbide produced from carbon and vanadium has a higher solid solution temperature than molybdenum carbide, in the carbonitriding temperature range in the production of the bearing component of the present invention, Most of the vanadium carbide that was present in the steel was not dissolved, but was present in the steel as undissolved vanadium carbide. Such insoluble vanadium carbide serves as a precipitation nucleus for carbide (VC), carbonitride [V (C, N)], nitride [(Cr, V) N], etc. during carbonitriding, This contributes to the refinement of precipitates such as carbides, carbonitrides and nitrides, and can improve the hardness and rolling fatigue life of steel materials. At the same time, vanadium should promote the nitriding reaction in the outermost surface layer of the steel material and suppress the carburization reaction (suppression of excessive carburization structure) by promoting the formation of carbonitrides and nitrides more than chromium in the steel material. Can do. Vanadium functions as an element for improving resistance to temper softening in the tempering process described later. From the viewpoint of obtaining the above effect, the content of vanadium contained in the steel material is 0.05% by mass or more, and by sufficiently suppressing the generation of vanadium carbide, the amount of solid solution carbon is sufficiently secured and fixed. From the viewpoint of securing a sufficient amount of retained austenite as the outer ring, which is a ring, it is less than 0.5% by mass.

In the steel material, silicon is an element necessary for deoxidation during refining of steel. In addition, silicon is an element having an effect of suppressing coarse growth of carbide because it has a property of being hardly dissolved in carbide.
From the viewpoint of obtaining the effect, the content of silicon contained in the steel material is 0.05% by mass or more, and before the carbonitriding process, sufficient workability is ensured, and the cost required for the steel material and processing is reduced. From the viewpoint of reducing, the content is 0.70% by mass or less.

In the steel material, manganese is an element that stabilizes austenite in the steel material. Manganese is an element that can easily increase the amount of retained austenite by increasing the amount contained in the steel material.
From the viewpoint of obtaining the above effects, the manganese content in the steel material is 0.05% by mass or more, increasing the amount of undissolved carbide in the steel material, precipitating the carbide, and hardening the steel material. From the viewpoint of improving the thickness and obtaining sufficient hot workability and machinability, it is 0.7% by mass or less, preferably 0.50% by mass or less.

In the steel material, molybdenum is an element having a stronger affinity for carbon than chromium, and is an element involved in the formation of carbides and carbonitrides. Molybdenum is an element that increases the solid solution temperature of carbides and carbonitrides at the temperature of carbonitriding when manufacturing the bearing component of the present invention, and increases undissolved carbides and carbonitrides. . Therefore, molybdenum is an important element for increasing the amount of fine carbides and carbonitrides in the surface carbonitriding layer after carbonitriding and increasing the hardness of the steel material. Molybdenum improves the hardenability of the steel material and increases the amount of retained austenite in the steel material. Furthermore, molybdenum is an element that efficiently precipitates carbide (M ₂₃ C ₆ type carbide) and carbonitride [M ₂₃ (C, N) ₆ type carbonitride].
From the viewpoint of obtaining the above effect, the content of molybdenum contained in the steel material is 0.10% by mass or more, and the viewpoint of reducing cost and the viewpoint of suppressing the generation of coarse eutectic carbide that becomes the starting point of fatigue fracture. To 1.0% by mass or less.

  Next, the obtained outer ring shaped material 64 (intermediate material) is predetermined at 850 to 900 ° C. in a carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume. Heating is maintained for a period of time, and then rapidly cooled to a predetermined temperature ["carbonitriding process", see FIG. 2 (c)].

  The carbon potential in the carbonitriding atmosphere is 0.9 or more from the viewpoint of making the surface hardness sufficiently hard, and the area ratio of the vanadium nitride or the precipitate containing vanadium carbonitride is within the above range. At the same time, it is 1.3 or less from the viewpoint of suppressing the occurrence of excessive carburized structure.

  In addition, the ammonia gas concentration in the carbonitriding atmosphere is 2% by volume or more from the viewpoint of suppressing the occurrence of excessive carburized structure and improving resistance to tempering and softening in the tempering process described later. From the viewpoint of preventing embrittlement, the content is 5% by volume or less.

The heating and holding temperature in the carbonitriding atmosphere is 850 ° C. or higher from the viewpoint of forming a sufficient hardened layer, and suppresses the excessive carbon intrusion into the bearing constituent member and suppresses the occurrence of excessive carburized structure. From the viewpoint of suppressing the precipitation of coarse carbides, the temperature is 900 ° C. or lower.
The heating and holding time is 4 hours or more from the viewpoint of obtaining a carburized depth sufficient for strengthening the surface layer.

  The rapid cooling is performed by oil cooling in an oil bath of cooling oil. The oil bath temperature of the cooling oil may usually be 60 to 180 ° C.

Next, sub-zero treatment is performed to cool the outer ring shaped material 64 (intermediate material) after carbonitriding to a predetermined temperature lower than 0 ° C. [Refer to “Sub-zero treatment”, FIG. 2 (d)].
The cooling temperature in the sub-zero treatment is preferably −100 ° C. or higher from the viewpoint of reducing costs, and preferably −50 ° C. or lower from the viewpoint of changing the retained austenite to a predetermined martensite.
In addition, the cooling time in the sub-zero treatment is preferably 1 hour or longer from the viewpoint of securing a static load capacity sufficient for use as a fixed wheel.
By performing the sub-zero treatment in this manner and changing the retained austenite to martensite, it is possible to ensure a sufficient static capacity for use as a fixed ring.

Next, a tempering process in which the outer ring shaped material 64 (intermediate material) after the sub-zero treatment is heated and held at a predetermined temperature is performed ["tempering process step", see FIG. 2 (e)].
The heating and holding temperature in the tempering treatment is 150 ° C. or higher from the viewpoint of ensuring heat resistance as a bearing, and is 250 ° C. or lower from the viewpoint of ensuring a predetermined hardness.
Further, the heating and holding time in the tempering treatment is 0.5 hour or more from the viewpoint of performing the treatment uniformly.

  Thereafter, the outer ring shaped material 64 (intermediate material) after the tempering process step is subjected to polishing finish processing on the portions forming the raceway surface 61a, end surface 61b, shoulder surface 61c, and outer peripheral surface 61d, and the raceway. The surface 61a is superfinished to finish it with a predetermined accuracy (see FIG. 2 (f), “finishing process”). Thus, the target outer ring 61 can be obtained. In the obtained outer ring 61, the raceway surface 61a, the end surface 61b, the shoulder surface 61c, and the outer peripheral surface 61d are configured as a polishing portion. Of the outer ring 61, the chamfer 61e on the outer peripheral side of the outer ring and the inner peripheral side of the outer ring are provided. The chamfer 61f is configured as a non-polished non-polished part.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited only to this Example.

[Examples 1 and 2 and Comparative Examples 1 to 7, Reference Examples 1 to 3]
Two types of steel materials A and B having the composition shown in Table 1 are each processed into a predetermined shape to form inner and outer rings and rolling surfaces for a ball bearing (model number 6206) having a grinding allowance at a portion where the raceway surface is formed. The shape material of each rolling element for ball bearings (model number 6206) having a grinding allowance was produced. Steel material B of Table 1 is JIS SUJ2 which is a bearing rope. The diameter of the rolling element was 9.525 mm.

  Next, the obtained shaped material was subjected to heat treatment under the heat treatment conditions shown in FIGS. 3 to 15, and a portion for forming the raceway surface of each intermediate material of the obtained inner and outer rings after heat treatment and obtained The ball bearings of Examples 1 and 2 and Comparative Examples 1 to 7 and Reference Examples 1 to 3 are manufactured by polishing each of the intermediate material of the rolling element after the heat treatment to form the rolling surface. did.

The heat treatment condition shown in FIG. 3 is that the raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.1 and an ammonia gas concentration of 2% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 180 ° C. for 2 hours (experiment number 1).
The heat treatment condition shown in FIG. 4 is that the raw material was heated at 850 ° C. for 4 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and an ammonia gas concentration of 2% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 160 ° C. for 2 hours (Experiment No. 2).
The heat treatment condition shown in FIG. 5 is that the raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.1 and an ammonia gas concentration of 2% by volume, and then oil-cooled to 80 ° C. Next, it is cooled (subzero treatment) at −55 ° C. for 1 hour and then heated (tempering treatment) at 200 ° C. for 2 hours (experiment number 3).
The heat treatment conditions shown in FIG. 6 are as follows: the raw material was heated at 850 ° C. for 5 hours in a carbonitriding atmosphere having a carbon potential of 1.1 and an ammonia gas concentration of 2% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 180 ° C. for 2 hours (experiment number 4).
The heat treatment condition shown in FIG. 7 is that the raw material was heated at 860 ° C. for 5 hours in a carbonitriding atmosphere having a carbon potential of 1.1 and an ammonia gas concentration of 2% by volume, and then oil-cooled to 80 ° C. Next, it is cooled (subzero treatment) at −75 ° C. for 1 hour, and then heated (tempering treatment) at 200 ° C. for 2 hours (experiment number 5).
The heat treatment conditions shown in FIG. 8 are as follows. The raw material was heated in an atmosphere having a carbon potential of 0.8 at 830 ° C. for 0.5 hours, quenched, then cooled to 80 ° C., and then oil cooled. And heating (tempering treatment) at 180 ° C. for 2 hours (Experiment No. 6).
The heat treatment conditions shown in FIG. 9 are as follows. The raw material was heated in a carburizing atmosphere having a carbon potential of 1.2 at 850 ° C. for 5 hours, then oil-cooled to 80 ° C., and then heated at 160 ° C. for 2 hours [ Tempering treatment] (Experiment No. 7).
The heat treatment conditions shown in FIG. 10 are as follows: the raw material was heated in an atmosphere having a carbon potential of 0.8 at 900 ° C. for 0.5 hours, quenched, then cooled to 80 ° C., and then oil cooled. And heating (tempering treatment) at 180 ° C. for 2 hours (Experiment No. 8).
The heat treatment conditions shown in FIG. 11 are as follows. The raw material was heated in a carburizing atmosphere with a carbon potential of 1.2 at 900 ° C. for 7 hours, then oil-cooled to 80 ° C., and then heated at 160 ° C. for 2 hours [ Tempering treatment] (Experiment No. 9).
The heat treatment condition shown in FIG. 12 is that the raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and an ammonia gas concentration of 1% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 180 ° C. for 2 hours (experiment number 10).
The heat treatment conditions shown in FIG. 13 are as follows: the raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and an ammonia gas concentration of 15% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 180 ° C. for 2 hours (experiment number 11).
The heat treatment conditions shown in FIG. 14 are as follows: the raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and an ammonia gas concentration of 5% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 180 ° C. for 2 hours (experiment number 12).
The heat treatment condition shown in FIG. 15 is that the raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.0 and an ammonia gas concentration of 2% by volume, and then oil-cooled to 80 ° C. Thereafter, heating (tempering treatment) is performed at 180 ° C. for 2 hours (experiment number 13).

In Example 1, the inner ring is the heat treatment condition (experiment number 1) shown in FIG. 3, the rolling element is the heat treatment condition (experiment number 2) shown in FIG. 4, and the outer ring is shown in FIG. Manufactured under heat treatment conditions (Experiment No. 3).
Moreover, in Example 2, the inner ring is under the heat treatment condition (experiment number 4) shown in FIG. 6, the rolling element is under the heat treatment condition (experiment number 2) shown in FIG. 4, and the outer ring is shown in FIG. Manufactured under heat treatment conditions (Experiment No. 5).
The outer ring, inner ring, and rolling element of the ball bearing of Comparative Example 1 were each manufactured under the heat treatment conditions (experiment number 6) shown in FIG.
The outer ring and the inner ring of the ball bearings of Comparative Example 2 and Comparative Examples 4 to 7 were manufactured under the heat treatment conditions (experiment number 7) shown in FIG. 9 to the heat treatment conditions (experiment number 11) shown in FIG. . The outer ring and inner ring of the ball bearing of Comparative Example 3 were manufactured under the heat treatment conditions (experiment number 2) shown in FIG. The outer ring and inner ring of the ball bearing of Reference Example 1 were manufactured under the heat treatment conditions (experiment number 1) shown in FIG. Further, the outer and inner rings of the ball bearings of Reference Examples 2 and 3 were manufactured under the heat treatment conditions shown in FIG. 14 (experiment number 12) and the heat treatment conditions shown in FIG. 15 (experiment number 13), respectively. The rolling elements of the ball bearings of Comparative Examples 2 to 7 and Reference Examples 1 to 3 were manufactured under the heat treatment conditions (experiment number 2) shown in FIG.

[Test Example 1]
About the outer ring of Examples 1 and 2, the inner ring used for the ball bearings of Examples 1 and 2, Comparative Examples 1 to 7, and the outer rings of Reference Examples 1 to 3, a depth of 50 μm from the surface (polishing part) of the raceway part Vickers hardness at the position (Rockwell C hardness), amount of retained austenite on the surface layer portion at a depth of 10 μm from the surface, carbon content in the surface layer in the range from the surface to 10 μm, 10 μm from the surface Nitrogen content, precipitate form, and vanadium-based precipitates in the surface layer in the range of up to 0.2-2 μm in particle size composed of vanadium carbonitride and 0.2-2 μm in particle size composed of vanadium nitride The area ratio of particles) was examined. Vickers hardness (Rockwell C hardness) at a depth of 50 μm from the surface of the rolling element used in the ball bearings of Examples 1 and 2 and surface layer retained austenite at a depth of 10 μm from the surface Amount, carbon content in the surface layer in the range from the surface to 10 μm, nitrogen content in the surface layer in the range from the surface to 10 μm, precipitate form, and vanadium-based precipitate (particle size of vanadium carbonitride 0 .2 to 2 μm particles and vanadium nitride particles having a particle size of 0.2 to 2 μm) were examined.

  In order to measure the hardness of the substantial surface layer, the Vickers hardness at a depth of 50 μm from the surface is 50 μm from the surface after cutting the inner and outer rings and the rolling elements in the depth direction from the surface. The measurement was made by applying a Vickers indenter to the position of the depth of. The Rockwell C hardness was determined by converting the measured Vickers hardness. The surface layer retained austenite amount at a depth of 10 μm from the surface is obtained by electropolishing up to a depth of 10 μm from the surface of the raceway portion of the inner ring and measuring the amount of retained austenite on the electropolished surface. It was. The carbon content in the range from the surface to 10 μm and the nitrogen content in the range from the surface to 10 μm are respectively in the range from the surface to 10 μm after the inner and outer rings and the rolling elements are cut in the depth direction from the surface. It was calculated | required by measuring each content in.

The precipitate form was evaluated by observing a range from the surface to 10 μm after cutting the inner and outer rings and rolling elements in the depth direction from the surface. The area ratio of vanadium-based precipitates (particles made of vanadium carbonitride having a particle size of 0.2 to 2 μm and particles of vanadium nitride having a particle size of 0.2 to 2 μm) depends on the surface of the inner and outer rings and rolling elements. After cutting in the depth direction, the measurement was performed in the range from the surface to 10 μm. The area ratio of the precipitate form and the vanadium-based precipitate (particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride and particles having a particle diameter of 0.2 to ² μm made of vanadium nitride) was 800 μm ^2. In the measurement field of view, carbon, nitrogen and vanadium were measured using a field emission electron probe microanalyzer under the conditions of acceleration voltage: 15.0 kV, irradiation current: 2.016 × 10 ⁻⁷ A and scan magnification: 3000 times. Mapping was performed, and the area ratio was calculated by an image processing apparatus.

  In addition, for each of the ball bearings of Examples 1 and 2 and Comparative Examples 1 to 7 and Reference Examples 1 to 3, the life in a lubricating oil mixed with foreign matter, which is one index of life (life in foreign matter oil), The track ring indentation depth, which is one index of static load capacity, was examined.

The life in foreign oil was tested under the conditions shown in Table 2. The foreign oil injection life was evaluated according to the following criteria.
〔Judgment criteria〕
○: Eight or more times the L10 life of the ball bearing of Comparative Example 1.
X: Less than 8 times the L10 life of the ball bearing of Comparative Example 1.

Further, the raceway indentation depth is determined by arranging the balls in the ball bearings of Examples 1 and 2 and Comparative Examples 1 to 7 and Reference Examples 1 to 3 on a vertical line, and applying a load of 14.7 kN from above in the vertical direction. In the ball bearing ring, the depth of the indentation at the portion where the maximum stress occurred was evaluated by measuring with a three-dimensional shape measuring instrument. The bearing ring indentation depth is a sum of the indentation depth generated in the inner ring and the indentation depth generated in the outer ring. The track ring indentation depth was evaluated according to the following criteria.
〔Judgment criteria〕
○: Indentation depth is 0.635 μm or less ×: Indentation depth is greater than 0.635 μm Note that “0.635 μm” is a smooth rotation in a ball bearing when the rolling element diameter is 9.525 mm. This is the amount of permanent deformation that is the limit that does not hinder. This value is equal to the inner ring, the outer ring, and the rolling element when the deformation due to the indentation is within the allowable limit of deformation due to the indentation in the entire rolling bearing determined by the rolling element diameter (9.525 mm) × 1/10000. Assuming that it occurs (1/3 of the whole), the combined value of the indentation depth of the inner ring and the indentation depth of the outer ring is 2/3 of the allowable limit of deformation due to the indentation in the entire rolling bearing. It is a value obtained by setting 2/3 of the allowable limit of deformation due to indentation in the entire rolling bearing as an allowable value.

Vickers hardness (Rockwell at a depth of 50 μm from the surface, the kind of steel material used for the outer ring of Examples 1 and 2 and the inner ring and rolling elements used for the ball bearings of Examples 1 and 2 and the rolling elements. C hardness), amount of retained austenite at a depth of 10 μm from the surface, carbon content in the surface layer in the range from the surface to 10 μm, nitrogen content in the surface layer in the range from the surface to 10 μm, precipitate form Table 3 shows the results of examining the area ratio of the vanadium-based precipitates and the life in foreign oil and the raceway indentation depth of the ball bearings of Examples 1 and 2.
Further, the types of steel materials used in the outer and inner rings of Comparative Examples 1 to 7 and Reference Examples 1 to 3, heat treatment conditions, Vickers hardness (Rockwell C hardness) at a depth of 50 μm from the surface, and 10 μm from the surface Amount of retained austenite at the depth of the surface, carbon content in the surface layer in the range from the surface to 10 μm, nitrogen content in the surface layer in the range from the surface to 10 μm, precipitate morphology, area ratio of vanadium-based precipitates Table 4 shows the results of examining the life in foreign oil and the indentation depth of the bearing rings of the ball bearings of Comparative Examples 1 to 7 and Reference Examples 1 to 3.
In Tables 3 and 4, “Vickers hardness (Rockwell C hardness)” indicates Vickers hardness (Rockwell C hardness) at a depth of 50 μm from the surface, and “Residual austenite amount ( Volume%) ”indicates the amount of retained austenite at a depth of 10 μm from the surface, and“ carbon content (mass%) ”and“ nitrogen content (mass%) ”are respectively 10 μm from the surface. The carbon content and the nitrogen content in the surface layer in the range are shown, and the “area ratio (%) of vanadium-based precipitates” is a particle size of 0.2 to 0.2 μm of vanadium nitride in the surface layer in the range from the surface to 10 μm. The area ratio of what combined 2 micrometers particle | grains and the particle | grains of particle diameter 0.2-2 micrometers which consist of vanadium carbonitride is shown.

From the results shown in Table 3, the life in foreign oil of the ball bearings of Examples 1 and 2 is 12 times or more the L10 life of the ball bearing of Comparative Example 1. Further, the raceway indentation depths of the ball bearings of Examples 1 and 2 are 0.35 μm and 0.38 μm, respectively, and the amount of permanent deformation (0.635 μm), which is the limit that does not hinder smooth rotation of the ball bearing. It is as follows.
Therefore, according to the combination of the outer ring and the inner ring in Examples 1 and 2, it is possible to extend the life of the rolling bearing and to secure a sufficient static load capacity.

On the other hand, from the results shown in Table 4, the life in foreign oil of the ball bearings of Comparative Examples 2 to 4 and 7 is less than 8 times (1 to 3 times) the L10 life of the ball bearing of Comparative Example 1. It can be seen that the life in foreign oil is shorter than that of the ball bearings of Examples 1 and 2. In addition, the indentation depth of the ball bearings of the ball bearings of Comparative Examples 1 to 4 and 7 is larger than 0.635 μm (0.82 to 2.0 μm), and the amount of permanent deformation that is the limit that does not hinder smooth rotation in the ball bearing. It turns out that it is above.
Furthermore, from the results shown in Table 4, the life in foreign matter oil of the ball bearings of Comparative Examples 5 and 6 is 8 times or more the L10 life of the ball bearing of Comparative Example 1 [each 10 times (Comparative Example 5) And 12 times (Comparative Example 6)], but the indentation depth of the race ring is larger than 0.635 μm [1.4 μm (Comparative Example 5) and 1.6 μm (Comparative Example 6), respectively]. It turns out that it is beyond the amount of permanent deformation which is the limit which does not prevent smooth rotation.

  Further, from the results shown in Table 4, in the ball bearings of Reference Examples 1 to 3, the life in foreign oil and the depth of the raceway indentation are both usable levels, but the balls of Examples 1 and 2 It can be seen that the indentation depth of the bearing ring is longer than that of the bearing, and the static load capacity is lower than that of the ball bearings of Examples 1 and 2.

Therefore, from these results, in the ball bearing which is a rolling bearing, carbonitriding with a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume with respect to the shaped material obtained by processing the steel material A. In the atmosphere, the carburizing treatment is performed on the driving wheel (inner ring) having the following predetermined value obtained by performing carbonitriding treatment that is heated at 850 to 900 ° C. and rapidly cooled. After that, by using a fixed ring (outer ring) having the following predetermined property obtained by subjecting the obtained intermediate material to sub-zero treatment at −50 to −100 ° C., the service life is extended. It can be seen that the static load capacity can be improved.
(1) Inner ring:
The content of carbon in the surface layer in the range from the surface to 10 μm is 1.1 to 1.6 mass%, and the Vickers hardness at a depth of 50 μm from the surface is 740 to 900 (Rockwell C hardness is 62 67), the amount of retained austenite at a depth of 10 μm from the surface is 20 to 55% by volume, the nitrogen content in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0% by mass, the surface To 10 μm in the surface layer, particles having a particle diameter of 0.2 to 2 μm composed of vanadium nitride and / or particles of a particle diameter of 0.2 to 2 μm composed of vanadium carbonitride, and from the surface The area ratio of particles having a particle diameter of 0.2 to 2 μm and / or particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride in the surface layer in the range of up to 10 μm is 1 to 10%.
(2) Outer ring:
The carbon content in the surface layer in the range from the surface to 10 μm is 1.1 to 1.6 mass%, and the Vickers hardness at a depth of 50 μm from the surface is 800 to 940 (Rockwell C hardness is 64 68), the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, the nitrogen content in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0% by mass, the surface To 10 μm on the surface layer having a particle size of 0.2 to 2 μm made of vanadium nitride and / or a particle of 0.2 to 2 μm made of vanadium carbonitride. The area ratio of particles having a particle diameter of 0.2 to 2 μm and / or particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride in the surface layer in the range up to 1 to 10%.

[Example 3 and Comparative Examples 8-12]
Each of the steel materials C and D shown in Table 5 was processed into a predetermined shape, and a shape material of an outer ring for a ball bearing (model number 6206) having a grinding allowance at a portion forming a raceway surface was manufactured. In addition, the steel material D of Table 5 is JIS SUJ2 which is bearing steel.

Next, the obtained shaped material is subjected to heat treatment under the heat treatment conditions shown in FIGS. 8 and 16 to 20, and further subjected to finishing by polishing, so that Example 3 which is a race member and Comparative Examples 8 to Twelve outer rings were produced.
The heat treatment conditions shown in FIG. 16 are as follows. The raw material was heated at 860 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and an ammonia gas concentration of 5% by volume, and then oil-cooled to 80 ° C. Next, it is maintained at −75 ° C. for 1 hour (sub-zero treatment), and then heated at 180 ° C. for 2 hours (tempering treatment).
The heat treatment conditions shown in FIG. 17 are as follows. The shaped material was heated at 850 ° C. for 5 hours in a carburizing atmosphere having a carbon potential of 1.2, then cooled to 80 ° C., and then heated at 180 ° C. for 2 hours [tempering. Process].
The heat treatment condition shown in FIG. 18 is that the raw material was heated at 850 ° C. for 4 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and an ammonia gas concentration of 5% by volume, and then oil-cooled to 80 ° C. Then, it is heated (tempered) at 180 ° C. for 2 hours.
The heat treatment conditions shown in FIG. 19 are as follows: the raw material was heated in an atmosphere having a carbon potential of 1.0 at 900 ° C. for 0.5 hours, quenched, then oil cooled to 80 ° C., , Heated at 180 ° C. for 2 hours (tempering treatment).
The heat treatment conditions shown in FIG. 20 are as follows: the shaped material was heated in a carburizing atmosphere with a carbon potential of 1.2 at 930 ° C. for 7 hours, followed by heating at 900 ° C. for 0.5 hour, and then 80 Oil-cooled to ℃, and then heated (tempered) at 180 ℃ for 2 hours.

[Test Example 2]
Regarding the outer rings of Example 3 and Comparative Examples 8 to 12, the heat treatment quality was examined.
Table 6 shows the types of steel materials used in the manufacture of the outer rings of Example 3 and Comparative Examples 8 to 12 and the heat treatment conditions.

  Table 7 shows the heat treatment quality of the surface (polishing portion) of the track portion, and Table 8 shows the heat treatment quality of the non-polishing portion. As the heat treatment quality of the surface of the track (polishing part), the Vickers hardness at a depth of 50 μm from the surface of the track (polishing part) (“Vickers hardness” in the table), the depth of 10 μm from the surface Surface layer retained austenite amount (in the table, “surface layer retained austenite amount”), internal retained austenite amount at a depth of 2 mm from the surface (in the table, “internal retained austenite amount”), Carbon content in the surface layer in the range from the surface to 10 μm (in the table, “carbon content”), nitrogen content in the surface layer in the range from the surface to 10 μm (in the table, “nitrogen content”), precipitation Vanadium-based precipitates in the surface layer in the range from the surface to 10 μm (particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride and particles having a particle diameter of 0.2 to 2 made of vanadium nitride) m particles) area ratio (in the table, “area ratio of vanadium-based precipitates”) and area ratio of precipitates containing nitride in the surface layer in the range from the surface to 10 μm (in the table, “nitride. The area ratio of the containing precipitates ") is shown respectively.

  Further, as the heat treatment quality of the non-polished part, the Vickers hardness at a depth of 50 μm from the surface of the non-polished part (“Vickers hardness” in the table), carbon in the surface layer in the range from the surface to 10 μm Content (in the table, “carbon content”), nitrogen content in the surface layer in the range from the surface to 10 μm (table, “nitrogen content”) and grains in the surface layer in the range from the surface to 10 μm The presence or absence of coarse carbon compound particles having a diameter of 10 μm or more (in the table, “coarse carbon compound particles having a particle diameter of 10 μm or more”) is shown.

From the results shown in Table 7 and Table 8, the outer ring of Example 3 obtained by subjecting the shaped material obtained from the steel material C to carbonitriding and then sub-zeroing, Vickers hardness is 880 at a depth of 50 μm from the surface of the part (polishing part), the surface layer portion retained austenite is 22% by volume at a depth of 10 μm from the surface, and the depth is 2 mm from the surface The amount of internal retained austenite at the position of 5% by volume, the carbon content in the surface layer in the range from the surface to 10 μm is 1.4% by mass, and the nitrogen content in the surface layer in the range from the surface to 10 μm is 0%. The area ratio of vanadium-based precipitates in the surface layer in the range from 6% by mass to 10 μm from the surface is 6%, and the area ratio of precipitates including nitride in the surface layer in the range from 10 μm to the surface is It can be seen that is 2%.
Further, in the non-polished part, the Vickers hardness at a position of 50 μm depth from the surface of the non-polished part is 800, the carbon content in the surface layer in the range of 10 μm from the surface is 0.8% by mass, To 10 μm, the nitrogen content in the surface layer is 1.3% by mass, and there is no coarse carbon compound particle having a particle size of 10 μm or more in the surface layer in the range from the surface to 10 μm.
In addition, nitride particles having a particle size of 500 nm or less were present on the surface (polishing portion) of the raceway portion of the outer ring of Example 3.
The surface (polishing portion) of the raceway portion of the polished outer ring of Example 3 has particles made of nitride having a particle size of 500 nm or less in the surface layer in a range from the polished surface to 10 μm. Since the area ratio of the precipitate containing nitride in the surface layer in the range from the surface to 10 μm is 5 to 20%, the hardness of the surface is improved, and it is used in lubricating oil mixed with foreign matter. Even in this case, the stress concentration around the indentation generated when a foreign object is caught can be relaxed.
From these results, it is suggested that the formation of the carbonitriding layer in the non-polished part as in the outer ring of Example 3 suppresses the occurrence of excessive carburized structure in the non-polished part.

  On the other hand, from the results shown in Table 7 and Table 8, the outer ring of Comparative Example 12 obtained by carburizing the raw material obtained from the steel material C has nitrogen (N) on the surface of the non-polished part. It can be seen that is not included. Moreover, since the coarse carbon compound particle | grains with a particle size of 10 micrometers or more exist in the non-polishing part of the outer ring | wheel of the comparative example 12, the excessive carburizing structure | tissue has generate | occur | produced.

[Test Example 3]
Next, for each of the inner and outer rings of Example 3 and Comparative Examples 8 to 12, a life test in a foreign oil and a crushing strength test were performed. When conducting the life test in the foreign oil, carbonitriding is performed on the outer and inner rings of each of Example 3 and Comparative Examples 8 to 12 and the high carbon chromium bearing steel (JIS SUJ2), followed by quenching and tempering. The ball bearing of model number 6206 was assembled by combining with the balls manufactured in this manner, and the obtained ball bearing was subjected to a life test in a foreign oil. The test conditions for the foreign oil life test are the conditions shown in Table 2 above. Table 9 shows the test conditions of the crushing strength test. In the crushing strength test, the first location in the circumferential direction of the 6206 outer ring and the second location where the first location in the circumferential direction was moved in the circumferential direction at 180 ° C. were measured in the radial direction with an Amsler tester. The first part and the second part are moved close to each other at a speed of 0.5 mm / min along a direction perpendicular to the axis of the 6206 outer ring connecting the first part and the second part. This is a test to evaluate the radial load when the 6206 outer ring is deformed, broken, and broken. The crushing strength ratio is the ratio of the load when the 6206 outer ring of each example and comparative example breaks to the load when the 6206 outer ring of comparative example 8 breaks. These results are shown in Table 10.

  From the results shown in Table 10, the ball bearing provided with the outer ring of Example 3 in which the steel material C having the composition shown in Table 5 was used is the ball bearing provided with the outer ring of Comparative Examples 8 to 12 in which the steel material D was used. In comparison, it can be seen that the life in foreign oil is longer and the crushing strength of the outer ring is also higher.

On the other hand, from the results shown in Table 10, the ball bearing provided with the outer ring of Comparative Example 12 in which carburizing treatment was performed on the shaped material obtained from the same steel material C as the steel material used for the outer ring of Example 3 was It can be seen that the crushing strength of the outer ring is lower than that of the ball bearing provided with the outer ring of Comparative Examples 8 to 10 in which the steel material D is used. In contrast, the ball bearing provided with the outer ring of Example 3 obtained by subjecting the shaped material obtained from the steel material C to carbonitriding has both the life in foreign oil and the crushing strength of the outer ring. It can be seen that it has improved.
As described above, in Comparative Examples 9 and 12, coarse carbon compound particles having a particle size of 10 μm or more exist in the non-polished portion existing in the portion excluding the track portion, and an excessive carburized structure such as free carbide is generated. It has been found that the excessive carburized structure decreases the crushing strength of the rolling bearing by becoming the starting point of stress concentration. And, in Example 3, by subjecting a predetermined steel material to carbonitriding under predetermined conditions, while forming a long-life structure (carburized structure) with less precipitates in the raceway portion of the rolling bearing, In the non-polished part, coarse carbon compound particles having a particle size of 10 μm or more are not generated, generation of excessive carburized structures such as free carbide is suppressed, reduction in crushing strength is suppressed, and high rolling fatigue life can be achieved. did it.

  Therefore, from these results, as shown in Example 3, according to the race member obtained by subjecting the shaped material obtained from the steel material C having the composition shown in Table 5 to the carbonitriding treatment, the non-polished portion is excessively increased. It is suggested that a carburized structure is not formed, and that a rolling bearing excellent in both foreign oil life and crushing strength can be obtained.

  51, 61 Outer ring, 51a, 61a Raceway part, 52 Inner ring, 52a Raceway part, 53 balls, 60 ball bearing

Claims (6)

And 3.2 to 5.0 mass% of chromium, with respect to industrial castings processing the steel material containing a less than 0.05 wt% 0.5 wt% vanadium, carbon potential 0.9 .3, in a carbonitriding atmosphere having an ammonia gas concentration of 2 to 5% by volume, after performing carbonitriding treatment by heating at 850 to 900 ° C. and quenching, -50 to −100 with respect to the obtained intermediate material A bearing component having a surface that is obtained by applying a sub-zero treatment at 0 ° C. and a finishing process, and has a polished finish,
The content of carbon in the surface layer in the range from the polished surface to 10 μm is 1.1 to 1.6 mass%, and the Vickers hardness at a depth of 50 μm from the surface is 800 to 940, the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, and the nitrogen content in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0. Mass%,
The surface layer in the range from the surface to 10 μm has particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and / or particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride. and if both the particle size 0.2~2μm of particles consisting of particles and vanadium carbonitride particle size 0.2~2μm consisting vanadium nitride on the surface layer is present, the The total area ratio of particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride in the surface layer is 1 to 10%, and the surface layer When either one of particles having a particle size of 0.2 to 2 μm made of vanadium nitride and particles having a particle size of 0.2 to 2 μm made of vanadium carbonitride is present, the particle size of vanadium nitride is 0. .2 to 2 μm particles and Bearing part of the area ratio of particles present in the surface layer of the particle size 0.2~2μm of particles consisting of vanadium carbonitride, characterized in that 1 to 10%. The bearing component member is a race member having a raceway portion that is polished and finished, and the steel material contains 0.7 to 0.9 mass% of carbon,
The carbon content in the surface layer in the range from the surface of the non-polished part existing in the part other than the track part to 10 μm is 0.7 to 1.0% by mass, and the position is 50 μm deep from this surface. The bearing component according to claim 1, having a Vickers hardness of 700 to 800. A rolling bearing having an outer ring having a raceway portion on an inner peripheral surface, an inner ring having a raceway portion on an outer peripheral surface, and a plurality of rolling elements arranged between both raceway portions of the outer inner ring,
A rolling bearing characterized in that the outer ring is a fixed ring and comprises the bearing constituent member according to claim 1. The inner ring is a drive wheel;
The carbon content in the surface layer in the range from the surface to 10 μm obtained from a steel material containing 3.2 to 5.0 mass% chromium and 0.05 mass% or more and less than 0.5 mass% vanadium. 1.1 to 1.6% by mass, the Vickers hardness at a depth of 50 μm from the surface is 740 to 900, and the amount of retained austenite at a depth of 10 μm from the surface is 20 to 55 The content of nitrogen in the surface layer in the range from the surface to 10 μm is 0.1 to 1.0% by mass,
The surface layer in a range from the surface to 10 μm has particles having a particle diameter of 0.2 to 2 μm and / or particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride. and if both the particle size 0.2~2μm of particles consisting of particles and vanadium carbonitride particle size 0.2~2μm consisting vanadium nitride on the surface layer is present, the surface The total area ratio of particles having a particle diameter of 0.2 to 2 μm made of vanadium nitride and particles having a particle diameter of 0.2 to 2 μm made of vanadium carbonitride in the layer is 1 to 10%, When either one of a particle having a particle size of 0.2 to 2 μm made of vanadium nitride and a particle having a particle size of 0.2 to 2 μm made of vanadium carbonitride is present, the particle size of vanadium nitride is 0. 2 to 2 μm particles and bar Rolling bearing according to claim 3 area ratio of particles present in the surface layer of the particle size 0.2~2μm of particles consisting of indium carbonitride is a member from 1 to 10%. A pre-processing step of obtaining a base material by processing a steel material containing 3.2 to 5.0% by mass of chromium and 0.05% by mass or more and less than 0.5% by mass of vanadium into a predetermined shape ,
Carburizing by heating the base material at 850 to 900 ° C. in a carbonitriding atmosphere having a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume with respect to the base material. Carburizing and nitriding process to obtain nitriding and intermediate material,
By subjecting the intermediate material after the carbonitriding process to a sub-zero treatment process for subjecting the intermediate material to cooling at −50 to −100 ° C., and applying a finishing process to the intermediate material after the sub-zero treatment process. The Vickers hardness at a depth of 50 μm from the surface is 800 to 940, the amount of retained austenite at a depth of 10 μm from the surface is 5 to 30% by volume, and the range from the surface to 10 μm The surface layer having a nitrogen content of 0.1 to 1.0 mass% and a surface layer in the range from the surface to 10 μm includes particles of vanadium nitride having a particle size of 0.2 to 2 μm and / or or consisting of vanadium carbonitrides have a particle diameter 0.2 to 2 .mu.m, and particles having a particle size 0.2 to 2 .mu.m consisting vanadium nitride on the surface layer and vanadium When both particle size 0.2~2μm of particles made of a nitride is present, the particle size 0 consisting of particles and vanadium carbonitride particle size 0.2~2μm consisting of vanadium nitride in the surface layer The total area ratio with the particles of 2 to 2 μm is 1 to 10%, and the surface layer has a particle size of 0.2 to 2 μm made of vanadium nitride and a particle size of 0.2 made of vanadium carbonitride. The surface of any of particles having a particle size of 0.2 to 2 μm made of vanadium nitride and particles having a particle size of 0.2 to 2 μm made of vanadium carbonitride when any one of the particles of ˜2 μm is present The manufacturing method of the bearing structural member characterized by including the finishing process of obtaining the bearing structural member whose area ratio of the particle | grains which exist in a layer is 1 to 10%. It is a manufacturing method of the race member as a bearing constituent member according to claim 2,
A steel material containing 0.7 to 0.9 mass% carbon, 3.2 to 5.0 mass% chromium, and 0.05 mass% or more and less than 0.5 mass% vanadium is formed into a predetermined shape. Processing to obtain a track member shape material having a grinding allowance in at least a portion forming the raceway surface,
In a carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and an ammonia gas concentration of 2 to 5% by volume, the raw material is heated at 850 to 900 ° C. for 4 hours or more. Carbonitriding process to obtain intermediate material by performing carbonitriding to quench
A sub-zero treatment step for subjecting the intermediate material after the carbonitriding treatment to a sub-zero treatment for cooling the intermediate material at −50 to −100 ° C., and a portion for forming the raceway surface of the intermediate material after the sub-zero treatment step In addition, the track portion is formed by polishing finishing, and the carbon content in the surface layer in the range from the surface of the track portion to 10 μm is 1.1% by mass or more and less than 1.6% by mass. The Vickers hardness at a position of a depth of 50 μm from this surface is 800 to 940, the amount of retained austenite at a position of a depth of 10 μm from the surface is 5 to 30% by volume, and from the surface to 10 μm The content of nitrogen in the surface layer in the range of 0.1 to 1.0% by mass and the surface layer in the range from the surface to 10 μm has a particle diameter of 0.2 to 2 μm made of vanadium nitride. The particles of the particulate and / or consisting of vanadium carbonitrides have a particle diameter 0.2 to 2 .mu.m, and particle size 0.2 to 2 .mu.m consisting vanadium nitride on the surface layer and vanadium When both particles having a particle size of 0.2 to 2 μm made of carbonitride are present , particles having a particle size of 0.2 to 2 μm made of vanadium nitride and a particle size made of vanadium carbonitride in the surface layer The total area ratio with 0.2 to 2 μm particles is 1 to 10%, and the surface layer has a particle size of 0.2 to 2 μm made of vanadium nitride and a particle size of vanadium carbonitride of 0. When any one of the particles having a particle size of 2 to 2 μm is present, the particles among the particles having a particle size of 0.2 to 2 μm made of vanadium nitride and the particles having a particle size of 0.2 to 2 μm made of vanadium carbonitride are used. surface of the particles present in the surface layer The rate is 1 to 10%, the carbon content in the surface layer in the range from the surface of the non-polished part existing in the part other than the track part to 10 μm is 0.7 to 1.0% by mass, and A method of manufacturing a race member as a bearing component, comprising a finishing step of obtaining a race member having a Vickers hardness of 700 to 800 at a depth of 50 μm from the surface.

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