JP5392100B2 - Rolling sliding member and manufacturing method thereof - Google Patents

Description

  The present invention relates to a rolling sliding member and a manufacturing method thereof.

In order to extend the life of rolling bearings used in automobiles and industrial machinery, as a steel material that forms bearing rings and rolling elements of bearings, alloys that contain many metals that contribute to improving hardenability and wear resistance It has been proposed to use a steel material made of (Patent Document 1).
In the said patent document 1, in order to improve hardenability and abrasion resistance as steel materials used for a rotation side bearing ring, 0.3-2.0 mass% of chromium, 0.1-1. It has been proposed to use bearing steel containing 0% by weight.
However, since bearing steel containing a large amount of rare metals such as chromium and molybdenum is expensive, the manufacturing cost of the rolling bearing increases.
Therefore, the use of carbon steel for mechanical structures, which is less expensive than bearing steel, as a material for rolling bearings has been studied.

JP 2002-194438 A

  However, carbon steel for machine structural use is inferior in hardenability compared to bearing steel, and cannot be hardened and hardened to a sufficient hardness, and is equivalent to a rolling bearing using a bearing steel such as SUJ2. The service life cannot be secured.

  The present invention has been made in view of such circumstances, and using a cheap material, a rolling sliding member capable of ensuring a life equal to or longer than that of a conventional bearing steel rolling sliding member, and It aims at providing the manufacturing method.

The rolling sliding member of the present invention is 0.1 to 0.5% by mass of carbon, 0.1 to 0.4% by mass of silicon, more than 0% by mass and 0.9% by mass or less. Of steel and a steel material containing more than 0% by mass and 0.2% by mass or less chromium and the balance being iron and inevitable impurities, and relatively rolling contact with the mating member or A rolling sliding member having a rolling sliding surface for making contact including sliding contact or both contact,
The surface of the rolling sliding surface has a Vickers hardness of 800 or more,
The carbon content at a position of a depth of about 10 μm from the surface of the rolling sliding surface is 0.6 to 1.2% by mass,
The nitrogen content at a position of a depth of about 10 μm from the surface of the rolling sliding surface is 0.4 to 0.9 mass%,
The total content of these carbon and nitrogen is 1.4% by mass or more,
The position at a depth of about 200 μm from the surface of the rolling sliding surface has particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride, and the position at a depth of about 200 μm from the surface. The area ratio of particles is 5 to 15%.

Since the rolling sliding member provided with the said structure was obtained from cheap steel materials, such as carbon steel for machine structures which has the said composition, it can be manufactured at a cheap material cost.
In addition, the rolling sliding member of the present invention has a Vickers hardness of 800 or more on the surface of the rolling sliding surface, and is formed of a nitride particle at a depth of about 200 μm from the surface of the rolling sliding surface. It has particles having a diameter of 0.03 μm or more and 1 μm or less, and the area ratio of the particles at a depth of about 200 μm from the surface is 5 to 15%, and the particles are dispersed and precipitated.
Note that the carbon content at a depth of about 10 μm from the surface is a range of ± 1 μm in the depth direction centered at a depth of 10 μm from the surface in the cross section in the depth direction from the surface. Refers to the carbon content. In addition, the nitrogen content at a depth of about 10 μm from the surface is a range of ± 1 μm in the depth direction centered at a depth of 10 μm from the surface in the cross section in the depth direction from the surface. Refers to the nitrogen content. In addition, the observation of nitride at a depth of about 200 μm from the surface shows that the cross section in the depth direction from the surface is ± 15 μm in the depth direction centered at a depth of 200 μm from the surface and with respect to the depth direction. A 30 μm square range of 30 μm is observed in the vertical direction as a visual field. Further, the area ratio of particles having a particle diameter of 1 μm or less made of nitride at a depth of about 200 μm from the surface means the area ratio of particles having a particle diameter of 0.03 μm to 1 μm in a 30 μm square range.
Therefore, the rolling sliding member of the present invention exhibits a hardness equal to or higher than that of a conventional rolling bearing member made of bearing steel on both the surface of the rolling sliding surface and the inside of the rolling sliding member. It is possible to ensure a life equal to or longer than that of a rolling sliding member made of bearing steel.

The manufacturing method of the rolling sliding member of this invention is a manufacturing method of the rolling sliding member provided with the said rolling sliding surface which makes a contact including a rolling contact or a sliding contact, or both contacts relatively between the other members. There,
0.1 to 0.5 mass% carbon, 0.1 to 0.4 mass% silicon, more than 0 mass% and not more than 0.9 mass% manganese, more than 0 mass%, And a steel material containing 0.2% by mass or less of chromium and the balance being iron and unavoidable impurities, and having a machining allowance at least at a portion forming the rolling sliding surface. Pre-processing step to obtain the profile,
In the carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and a residual ammonia amount of 1 to 1.4% by volume, the raw material is heated at 850 to 950 ° C. and rapidly cooled. Carbonitriding process to obtain an intermediate material,
An induction hardening process for subjecting at least a portion of the intermediate material after the carbonitriding process to form the rolling sliding surface to an induction hardening process in which the intermediate material is heated to a temperature of 850 to 1000 ° C. and rapidly cooled;
The tempering step of tempering the intermediate material after the induction hardening process at 160 to 200 ° C., and polishing the portion of the intermediate material after the tempering step that forms the rolling sliding surface, thereby rolling the rolling material. A moving surface is formed, the surface of the rolling sliding surface has a Vickers hardness of 800 or more, and the carbon content at a depth of about 10 μm from the surface of the rolling sliding surface is 0.6-1 .2% by mass, the nitrogen content at a position approximately 10 μm deep from the surface of the rolling sliding surface is 0.4 to 0.9% by mass, and the total of these carbon and nitrogen contents Is 1.4% by mass or more, and has particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride at a position approximately 200 μm deep from the surface of the rolling sliding surface, and Approximately 200 μm deep from the surface of the rolling sliding surface It includes a polishing step for obtaining a rolling sliding member having an area ratio of the particles at a position of 5 to 15%.

In the manufacturing method of the rolling sliding member of the present invention, the steel material is used, and the carbonitriding process is performed on the shaped material obtained by processing the steel material, and at least the portion that forms the rolling sliding surface. Since the induction hardening process and the polishing process are performed, the Vickers hardness of the surface of the rolling sliding surface of the obtained rolling sliding member is 800 or more, and the carbon content at a depth of about 10 μm from the surface 0.6 to 1.2% by mass, the nitrogen content at a position approximately 10 μm deep from the surface of the rolling sliding surface is 0.4 to 0.9% by mass, and the content of these carbon and nitrogen The total amount is 1.4% by mass or more, particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride are present at a depth of about 200 μm from the surface of the rolling sliding surface, and the rolling sliding surface At a position approximately 200 μm deep from the surface The area ratio of the serial particles can be 5-15%.
Therefore, according to the method for manufacturing a rolling sliding member of the present invention, it is possible to obtain a rolling sliding member having the above-described excellent effects.

  According to the rolling sliding member and the manufacturing method thereof of the present invention, it is possible to ensure a life equal to or longer than that of a conventional rolling bearing member made of bearing steel using a low cost material.

It is a schematic explanatory drawing which shows the structure of the ball bearing provided with the rolling sliding member concerning one Embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the structure | tissue in the rolling sliding member which concerns on one Embodiment of this invention. It is process drawing which shows the manufacturing method of the rolling sliding member (outer ring) which concerns on one Embodiment of this invention. It is a schematic explanatory drawing which shows the induction hardening process of the manufacturing method shown by FIG. 3 is a diagram showing heat treatment conditions in Example 1. FIG. It is a diagram which shows the heat processing conditions in Example 2. FIG. 6 is a diagram showing heat treatment conditions in Example 3. FIG. It is a diagram which shows the heat processing conditions in Example 4. FIG. It is a diagram which shows the heat processing conditions in the comparative example 1. It is a diagram which shows the heat processing conditions in the comparative example 2. It is a diagram which shows the heat processing conditions in the comparative example 3. It is a diagram which shows the heat processing conditions in the comparative example 4. It is a diagram which shows the heat processing conditions in the comparative example 5. It is a diagram which shows the heat processing conditions in the comparative example 6.

(Rolling sliding member)
Hereinafter, a rolling sliding 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 provided with a rolling sliding member according to an embodiment of the present invention.

  The ball bearing 10 includes both an outer ring 1 having a raceway surface 1a as a rolling sliding surface on an inner peripheral surface, an inner ring 2 having a raceway surface 2a as a rolling sliding surface on an outer peripheral surface, and both raceways of the outer inner rings 1 and 2. A plurality of balls 3 as rolling elements, which are arranged between the surfaces 1a and 2a and have a rolling surface as a rolling sliding surface on the surface, and a cage for holding the plurality of balls 3 at predetermined intervals in the circumferential direction. 4 is provided. The outer inner rings 1 and 2 and the balls 3 are rolling sliding members according to this embodiment.

Outer inner rings 1 and 2 and ball 3 are 0.1 to 0.5% by mass of carbon, 0.1 to 0.4% by mass of silicon, more than 0% by mass and 0.9% by mass or less. This is obtained from a steel material containing manganese, more than 0 mass% and chromium of 0.2 mass% or less, and the balance iron and inevitable impurities. Since such steel materials can be obtained at low cost, the outer inner rings 1 and 2 and the balls 3 can be manufactured at low cost.
Examples of the steel material include carbon steel for mechanical structure such as S25C, S35C, and S45C.

  In the ball bearing 10, the Vickers hardness of each of the raceway surfaces 1a and 2a of the outer inner rings 1 and 2 and the rolling surface of the ball 3 is 800 or more, and a conventional rolling sliding member made of bearing steel is used. Shows sufficient hardness equivalent or better.

  From the viewpoint of ensuring sufficient hardness, the carbon content at a position of a depth of about 10 μm from the surfaces of both raceway surfaces 1a and 2a of the outer inner rings 1 and 2 and the rolling surfaces of the balls 3 is 0. It is 6% by mass or more, and is 1.2% by mass or less from the viewpoint of securing sufficient toughness and further improving the life.

  The nitrogen content at a position of a depth of about 10 μm from both the raceway surfaces 1a, 2a of the outer inner rings 1, 2 and the rolling surfaces of the balls 3 is an amount sufficient to obtain a predetermined hardness. From the viewpoint of precipitating nitride particles, the content is 0.4% by mass or more, and from the viewpoint of sufficiently obtaining the quenching effect, it is 0.9% by mass or less.

  The total content of carbon and nitrogen precipitates a sufficient amount of nitride particles to obtain a predetermined hardness, and distributes the particles substantially uniformly throughout the rolling sliding member so that sufficient hardness is obtained. From the viewpoint of securing the thickness and toughness, it is 1.4% by mass or more.

Further, particles having a particle diameter of 1 μm or less made of nitride exist at positions at a depth of approximately 200 μm from both the raceway surfaces 1 a and 2 a of the outer inner rings 1 and 2 and the rolling surfaces of the balls 3. . As a result, the outer inner rings 1 and 2 and the balls 3 ensure sufficient hardness as well as wear resistance.
The particles preferably have a particle size of 0.03 μm or more from the viewpoint of ensuring wear resistance, and preferably have a particle diameter of 1 μm or less from the viewpoint of ensuring a sufficient life.

And the area ratio of the said particle | grain in the position of the depth of about 200 micrometers from each surface of both the raceway surfaces 1a and 2a of the outer inner rings 1 and 2 and the rolling surface of the ball 3 is a nitride having a large particle diameter in the surface layer. From the viewpoint of ensuring a sufficient life by reducing the abundance of particles consisting of the above, the austenite structure is less than 5%, and by reducing the abundance of particles of a small particle size nitride in the surface layer From the viewpoint of facilitating the formation of martensite and securing sufficient hardness, it is 15% or less.
Thereby, in the outer inner rings 1 and 2 and the balls 3, as shown in FIG. 2, particles (nitride particles 53) made of nitride having a particle diameter of 0.03 μm to 1 μm are austenite grain boundaries 52 in the base material 50. In such a state, they are dispersed in a substantially uniform manner and are deposited, and a sufficient hardness is ensured in each of them. Therefore, the outer inner rings 1 and 2 and the balls 3 exhibit excellent fatigue resistance and have a long life.

(Method for manufacturing rolling sliding member)
Next, a method for manufacturing the outer ring 1 will be described as an example of a method for manufacturing a rolling sliding member. FIG. 3 is a process diagram of an outer ring manufacturing method according to an embodiment of the present invention.

First, 0.1 to 0.5 mass% carbon, 0.1 mass% to 0.4 mass% silicon, manganese exceeding 0 mass% and 0.9 mass% or less, and 0 mass% An annular material 13 (see FIG. 3 (a)) of the outer ring 1 made of a steel material (carbon steel) containing chromium exceeding 0.2% by mass and the balance iron and inevitable impurities is obtained and obtained. The annular material 13 is cut into a predetermined shape and processed into a predetermined shape, and an outer ring shaped member 14 having a grinding allowance is formed in each of the portions forming the raceway surface 11a, the end surface 11b, the inner peripheral surface 11c, and the outer peripheral surface 11d. [Refer to “Pre-processing step”, FIG. 3B].
In such a pre-processing step, since the steel material such as the carbon steel for mechanical structure that can be obtained at low cost is used, the outer ring 1 can be manufactured at a low cost.

  Next, the outer ring shaped material 14 (intermediate material) obtained was 850 to 950 ° C. in a carbonitriding atmosphere having a carbon potential of 0.9 to 1.3 and a residual ammonia amount of 1 to 1.4% by volume. For a predetermined time, and then rapidly cooled to a predetermined temperature ["carbonitriding step", see FIG. 3 (c)].

  The carbon potential in the carbonitriding atmosphere is 0.9 or more from the viewpoint of obtaining sufficient hardness on the surface of the outer ring 1 and 1.3 or less from the viewpoint of ensuring toughness in the outer ring 1.

  Further, the amount of residual ammonia in the carbonitriding atmosphere is 1% by volume or more from the viewpoint of ensuring the area ratio of the particles made of the nitride and ensuring sufficient hardness, and uneven distribution of nitrides having a large particle size. From the viewpoint of preventing and securing sufficient toughness, it is 1.4% 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 the excessive carbon intrusion into the rolling sliding member is suppressed to suppress the occurrence of excessive carburized structure. At the same time, the temperature is 950 ° C. or lower from the viewpoint of preventing ammonia in the carbonitriding atmosphere from being decomposed and preventing nitrogen from entering the rolling sliding member.
The heating and holding time is 5 to 10 hours from the viewpoint of obtaining a carburization depth sufficient for strengthening the surface layer. The range from the surface to a depth of at least 500 μm is a carbonitriding layer. Usually, such a carbonitrided layer is formed to a depth of about 800 μm from the surface. The position deeper than the carbonitriding layer is not carbonitrided.

  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, the intermediate material is heated at 850 to 1000 ° C. and rapidly cooled with respect to the portions forming the raceway surface 11a, end surface 11b, inner peripheral surface 11c and outer peripheral surface 11d of the intermediate material 15 of the outer ring obtained. Induction hardening is performed (see “Induction hardening process”, FIG. 3D).

  For example, induction heating coil 101 (see FIG. 4A) smaller than the inner diameter of intermediate material 15 and induction heating coil 102 larger than the outer diameter of intermediate material 15 (see FIG. 4) (B)) and an induction heating coil 103 (see FIG. 4C) surrounding the end surface 11b of the intermediate material 15 can be used. Thereby, the induction hardening process can be performed on the portions forming the raceway surface 11a, the outer peripheral surface 11d, and the end surface 11b of the intermediate material 15 of the outer ring.

In the present specification, the heating temperature at the time of induction hardening is the temperature of the surface layer in the range of 2 mm from the surface of the portion forming the raceway surface 11a, outer peripheral surface 11d, and end surface 11b of the intermediate material 15. means. The heating temperature is 850 ° C. or more from the viewpoint of sufficiently intruding and dispersing the nitride into the intermediate material 15, and 1000 ° C. or less from the viewpoint of suppressing the disappearance of the nitride of the intermediate material 15. Thus, the effective hardened layer depth is ensured by heating the surface layer in a range of 2 mm from the surface of the portion forming the raceway surface 11a, outer peripheral surface 11d, and end surface 11b of the intermediate material 15 to the steam temperature. be able to.
The heating and holding time when the induction hardening process is performed is sufficient as long as the surface can be set to a predetermined temperature, and varies depending on the size of the intermediate material 15. Such heating and holding time is usually 1 to 10 seconds.

Next, the tempering process which heat-holds the intermediate raw material 15 after the said carbonitriding process at the temperature of 160-200 degreeC is performed ("tempering process process", refer FIG.3 (e)).
The heating and holding temperature in the tempering treatment is 160 ° C. or higher from the viewpoint of securing sufficient hardness, and is 200 ° C. or lower from the viewpoint of recovering toughness after quenching.
In addition, the heating and holding time in the tempering process is not particularly limited, but can usually be 30 minutes or longer.

  Thereafter, the portions forming the raceway surface 11a, the end surface 11b, and the outer peripheral surface 11d of the intermediate material 15 of the outer ring after the tempering process are polished and finished to a predetermined accuracy [see FIG. 3 (f)]. , “Polishing process”. In this way, the target outer ring 11 can be obtained.

  In addition, the manufacturing method of the rolling sliding member of this invention is employable also in manufacture of an inner ring | wheel and a rolling element.

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

[Examples 1 to 4 and Comparative Examples 1 to 5]
S25C, which is carbon steel for machine structural use, is processed into a predetermined shape, and the shape material of each of the inner and outer rings for ball bearings (model number 6206) having a grinding allowance at the portion forming the raceway surface as the rolling sliding surface is manufactured. did. Next, the obtained shaped material is subjected to heat treatment under the heat treatment conditions shown in FIG. 5 to FIG. 13, and a polishing process is performed on a portion forming the raceway surface of the obtained intermediate material. The inner and outer rings of 1-4 and Comparative Examples 1-5 were manufactured. The elemental composition of S25C is as follows: carbon 0.20 to 0.30 mass%, silicon 0.15 to 0.40 mass%, manganese 0.30 to 0.60 mass%, chromium 0.05 to 0.15 Mass%, balance iron and inevitable impurities.

Here, the heat treatment condition shown in FIG. 5 is that the shaped material is heated at 870 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 1.2% by volume, and then 80 ° C. Oil-cooled (carbonitriding), and the intermediate material obtained is heated at 900 ° C. for 10 seconds by induction quenching, then water-cooled (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment). (Inner and outer rings of Example 1).
The heat treatment conditions shown in FIG. 6 are as follows: the shaped material was heated at 920 ° C. for 5 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 1.2% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Example 2).
The heat treatment conditions shown in FIG. 7 are as follows: the raw material was heated at 930 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 1.1% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Example 3).
The heat treatment conditions shown in FIG. 8 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 a residual ammonia amount of 1.4% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Example 4).
The heat treatment condition shown in FIG. 9 is that the shaped material was heated at 950 ° C. for 5 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 0.8% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Comparative Example 1).
The heat treatment conditions shown in FIG. 10 are as follows. The shaped material was heated at 900 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 1.8% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Comparative Example 2).
The heat treatment conditions shown in FIG. 11 are as follows. The shaped material was heated at 900 ° C. for 5 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 1.6% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Comparative Example 3).
The heat treatment conditions shown in FIG. 12 are as follows. The shaped material was heated at 840 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 1.7% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Comparative Example 4).
The heat treatment conditions shown in FIG. 13 are as follows. The shaped material was heated at 920 ° C. for 7 hours in a carbonitriding atmosphere having a carbon potential of 1.2 and a residual ammonia amount of 0.9% by volume, and then oil-cooled to 80 ° C. (Carbonitriding), the obtained intermediate material is heated at 900 ° C. for 10 seconds by induction quenching, then cooled with water (induction quenching treatment), and heated at 170 ° C. for 2 hours (tempering treatment) ( Inner and outer rings of Comparative Example 5).

[Comparative Example 6]
Using the SUJ2 which is a bearing steel, each of the shape members for manufacturing the inner and outer rings of the ball bearing of model number 6206 was manufactured. Next, the obtained shaped material was subjected to heat treatment under the heat treatment conditions shown in FIG. 14 to produce the inner and outer rings of Comparative Example 6.
The heat treatment conditions shown in FIG. 14 are those in which the shaped material is heated at 840 ° C. for 0.5 hour, then oil cooled to 80 ° C. (quenching), and heated at 180 ° C. for 2 hours (tempering treatment). It is.

[Test Example 1]
For the inner rings of Examples 1 to 4 and Comparative Examples 1 to 6, the Vickers hardness at a position of a depth of 50 μm from the surface of the raceway surface, the carbon content at a position of a depth of about 10 μm from the surface of the raceway surface, Investigate the nitrogen content at a depth of approximately 10 μm from the surface of the raceway surface, and the area ratio of particles having a particle size of 0.03 μm to 1 μm consisting of nitride at a depth of approximately 200 μm from the surface of the raceway surface. It was. Moreover, the life test was done about the ball bearing which has each inner / outer ring of Examples 1-4 and Comparative Examples 1-6.

  The Vickers hardness at a depth of 50 μm from the surface was measured by cutting the inner ring in the depth direction from the surface and then applying a Vickers indenter at a depth of 50 μm from the surface.

  The carbon content at a depth of about 10 μm from the surface and the nitrogen content at a depth of about 10 μm from the surface are respectively 10 μm from the surface after cutting the inner ring in the depth direction from the surface. It was determined by measuring each content in a range of ± 1 μm in the depth direction with the position of the depth of the center.

The observation of nitride at a depth of about 200 μm from the surface is, in a cross section in the depth direction from the surface, ± 15 μm in the depth direction centered at a depth of 200 μm from the surface and perpendicular to the depth direction. The range of 30 μm square in the direction was 30 μm. The area ratio of particles having a particle size of 0.03 μm or more and 1 μm or less made of nitride at a depth of about 200 μm from the surface is an acceleration voltage of 15.0 kV and an irradiation current of 2.016 × in a measurement field of 800 μm ^2. Nitrogen was mapped using a field emission electron probe microanalyzer under the conditions of 10 ⁻⁷ A and scan magnification of 3000 times, and the area ratio was calculated with an image processing apparatus.

In addition, the life test was carried out using Examples 1 to 4 and Comparative Examples 1 to 6 and JIS SUJ2 and the rolling elements subjected to the same heat treatment as Comparative Example 6, respectively. Each ball bearing of -4 and Comparative Examples 1-6 was assembled, and each ball bearing obtained was tested under the conditions shown in Table 1. And the test of measuring the time until the inner ring of the ball bearing was broken was repeated five times, and the L ₁₀ life estimated to have a 10% damage probability by the Weibull distribution was obtained.

These results are shown in Table 2. In Table 2, the “carbon content” is the carbon content at a depth of about 10 μm from the surface of the raceway surface, and the “nitrogen content” is the location at a depth of about 10 μm from the surface of the raceway surface. Nitrogen content, “area ratio of particles made of nitride” is the area ratio of particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride at a depth of about 200 μm from the surface of the raceway surface, “Vickers” hardness "is a Vickers hardness of the surface of the raceway surface," lifetime "refers to the L ₁₀ life, respectively. The life was calculated as a relative value with the life of the ball bearing of Comparative Example 6 as 1.

  From the results shown in Table 2, in the inner rings of Examples 1 to 4, the carbon content at a depth of about 10 μm from the surface of the raceway surface is in the range of 0.6 to 1.2 mass%. The nitrogen content at a depth of about 10 μm from the surface of the raceway surface is in the range of 0.4 to 0.9 mass%, and the total content of carbon and nitrogen is 1.4 mass% or more. And that the area ratio of the particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride at a position approximately 200 μm deep from the surface of the raceway surface is in the range of 5 to 15%. I understand that. On the other hand, it can be seen that the inner rings of Comparative Examples 1 to 5 do not satisfy any of the carbon content range, the nitrogen content range, the total carbon and nitrogen content range, or the area ratio range.

  Moreover, from the results shown in Table 2, it can be seen that the inner rings of Examples 1 to 4 have a surface Vickers hardness of 800 or more. On the other hand, in the inner rings of Comparative Examples 1 to 5, it can be seen that the Vickers hardness at a position 50 μm deep from the surface is less than 800.

  Furthermore, it can be seen from the results shown in Table 2 that the ball bearings of Examples 1 to 4 have a lifespan three times or more that of the ball bearing of Comparative Example 6. On the other hand, in the ball bearings of Comparative Examples 1 to 5, it can be seen that the life of the ball bearing of Comparative Example 6 is 1.5 times or less.

Generally, as a steel material for producing a rolling sliding member, as in S25C, 0.1 to 0.5 mass% carbon, 0.1 mass% to 0.4 mass% silicon, An inexpensive steel material containing more than 0% by mass and not more than 0.9% by mass of manganese and more than 0% by mass and not more than 0.2% by mass of chromium, with the balance being iron and inevitable impurities When used, it is considered that the amount of retained austenite is large, the hardenability is insufficient, and the hardness of the surface becomes insufficient only by performing carbonitriding.
However, as can be seen from the results shown in Table 2, as a steel material, 0.1 to 0.5 mass% carbon, 0.1 mass% to 0.4 mass% silicon, and more than 0 mass%, When 0.9% by mass or less of manganese and 0% by mass and 0.2% by mass or less of chromium are used, and an inexpensive steel (S25C) in which the balance is iron and inevitable impurities is used. Even so, it is heated at 850 to 950 ° C. in a carbonitriding atmosphere having a carbon potential of 0.9 to 1.3 and a residual ammonia amount of 1 to 1.4% by volume with respect to such a steel shaped material. The intermediate material after the carburizing treatment is heated to a temperature of 850 to 1000 ° C. by induction hardening, rapidly cooled (induction hardening treatment), and after the induction hardening treatment. Intermediate material 160-200 In heating (tempering process), the intermediate material after tempering treatment, by performing the polishing, it is understood that it is possible to obtain in a sliding member rolling exhibit sufficient hardness and life cost.

Moreover, nitride is deposited on the surface of the obtained intermediate material by performing carbonitriding on the steel material. However, this nitride tends to be unevenly distributed in the intermediate material and is weak against rolling fatigue. In addition, the nitride is dissolved in the base material constituting the intermediate material by being heated at a high temperature for a long time, or released from the surface of the intermediate material. The effect may not be obtained sufficiently.
However, in the inner and outer rings of Examples 1 to 4, since the induction quenching process is performed on the intermediate material after the carbonitriding process, it is possible to sufficiently disperse the nitride particles. It is strong against rolling fatigue, and sufficient hardness can be secured even inside the intermediate material.

1 outer ring, 1a raceway surface, 2 inner ring, 2a raceway surface, 4 cage, 10 ball bearing,
11 Outer ring

Claims (3)

0.1 to 0.5% by mass of carbon, 0.1 to 0.4% by mass of silicon, more than 0% by mass and not more than 0.9% by mass of manganese, and more than 0% by mass And 0.2% by mass or less of chromium, and the balance is obtained from a steel material that is iron and unavoidable impurities, and is relatively rolling contact or sliding contact with a mating member or contact including both contacts. A rolling sliding member having a rolling sliding surface
The surface of the rolling sliding surface has a Vickers hardness of 800 or more,
The carbon content at a position of a depth of about 10 μm from the surface of the rolling sliding surface is 0.6 to 1.2% by mass,
The nitrogen content at a position of a depth of about 10 μm from the surface of the rolling sliding surface is 0.4 to 0.9 mass%,
The total content of these carbon and nitrogen is 1.4% by mass or more,
The position at a depth of about 200 μm from the surface of the rolling sliding surface has particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride, and the position at a depth of about 200 μm from the surface. A rolling sliding member having an area ratio of particles of 5 to 15%. A method of manufacturing a rolling sliding member provided with the rolling sliding surface that makes a contact including a rolling contact or a sliding contact or both contacts relative to a counterpart member,
0.1 to 0.5 mass% carbon, 0.1 to 0.4 mass% silicon, more than 0 mass% and not more than 0.9 mass% manganese, more than 0 mass%, And a steel material containing 0.2% by mass or less of chromium and the balance being iron and unavoidable impurities, and having a machining allowance at least at a portion forming the rolling sliding surface. Pre-processing step to obtain the profile,
In the carbonitriding atmosphere with a carbon potential of 0.9 to 1.3 and a residual ammonia amount of 1 to 1.4% by volume, the raw material is heated at 850 to 950 ° C. and rapidly cooled. Carbonitriding process to obtain an intermediate material,
An induction hardening process for subjecting at least a portion of the intermediate material after the carbonitriding process to form the rolling sliding surface to an induction hardening process in which the intermediate material is heated to a temperature of 850 to 1000 ° C. and rapidly cooled;
The tempering step of tempering the intermediate material after the induction hardening process at 160 to 200 ° C., and polishing the portion of the intermediate material after the tempering step that forms the rolling sliding surface, thereby rolling the rolling material. A moving surface is formed, the surface of the rolling sliding surface has a Vickers hardness of 800 or more, and the carbon content at a depth of about 10 μm from the surface of the rolling sliding surface is 0.6-1 .2% by mass, the nitrogen content at a position approximately 10 μm deep from the surface of the rolling sliding surface is 0.4 to 0.9% by mass, and the total of these carbon and nitrogen contents Is 1.4% by mass or more, and has particles having a particle diameter of 0.03 μm or more and 1 μm or less made of nitride at a position approximately 200 μm deep from the surface of the rolling sliding surface, and Approximately 200 μm deep from the surface of the rolling sliding surface The manufacturing method of the rolling sliding member characterized by including the grinding process process of obtaining the rolling sliding member whose area ratio of the said particle | grain in a position is 5 to 15%.   The method of manufacturing a rolling sliding member according to claim 2, wherein the rolling sliding member is an inner ring, an outer ring, or a rolling element of a rolling bearing.

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