JPH09256105A - Bearing element parts and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide bearing element parts prepared by the use of inexpensive steel, easy in forming into desired shape, reduced in dimensional change, and having a long rolling fatigue life and its production. SOLUTION: The bearing element parts have a base material constituted of a steel material which has a chemical composition consisting of, by weight, 0.7-1.2% C, >1.15-2.0% Mn, 0.3-1.6% Cr, 0-0.1% Nb, 0-0.2% V, <0.4% Si, <=0.02% P, <=0.02% S, >0.0005-0.0020% O, and the balance Fe with impurities and satisfying P+S=>0.01 to 0.04%, and further, a structure after quench-and- temper treatment is composed of martensite, spheroidal carbide, and retained austenite and the area ratio of the retained austenite is 5-15%. The steel having the chemical composition is subjected to spheroidizing, formed into parts, heated to 750-820 deg.C and hardened, and further tempered at 100-200 deg.C. By this procedure, a structure after quench-and-temper treatment is composed of martensite, spheroidal carbide, and retained austenite, and also the area ratio of the retained austenite can be regulated to 5-15%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing element component and a method for manufacturing the same, and more particularly, to rolling bearings such as ball bearings and roller bearings used in various industrial machines and automobiles, especially under a high surface pressure environment. TECHNICAL FIELD The present invention relates to an element part of a rolling bearing used in and a manufacturing method thereof.

[0002]

2. Description of the Related Art High surface pressure is repeatedly applied to rolling bearings such as ball bearings and roller bearings used in various industrial machines and automobiles. Therefore, the bearing element parts "outer ring", "inner ring", and "balls" and "rollers" that make rolling contact between the two require long rolling contact fatigue life.

In recent years, due to higher engine output and smaller peripheral parts, the rolling bearing has become more and more difficult to use due to higher surface pressure and higher temperature. There is a demand for a longer service life against rolling fatigue.

The above-mentioned bearing element parts are conventionally JIS G 48
SUJ which is a high carbon chrome bearing steel steel standardized to 05
1 to 5, in particular, SUJ2 as a base material (hereinafter also referred to as “raw steel”), hot-worked by means such as hot rolling, spheroidized and then cold-forged into a desired shape. Then, it is manufactured by quenching and tempering at a low temperature, and then grinding and polishing as a finishing process. However, when the above JIS standard steel is used as the base material, in the severe environment where the bearing is used, early damage due to rolling fatigue occurs.

Therefore, new bearing steels replacing the JIS standard steels are disclosed in, for example, Japanese Patent Laid-Open Nos. 2-3073 and 6-3.
-264186, Japanese Patent Laid-Open No. 61-272349, Japanese Patent Laid-Open No. 1-306542, and the like.

In Japanese Patent Laid-Open No. 2-30733, the weight% is
1.0 to 2.0% Ni, 1.0 to 2.0% Si
And further contain P and S, which are impurity elements, by weight%.
In order to improve the rolling fatigue life, the "high carbon chromium bearing steel" is disclosed.

However, in the bearing steel proposed in the above publication, Si and Ni are 1.0 to 2.% by weight, respectively.
It also contains 0%, and in particular, such a large amount of addition of Si causes a remarkable deterioration in cold forgeability. Moreover, 1.0-2.
The inclusion of 0% of Ni significantly increases the cost of the base material, and cannot meet the demand of the industry for manufacturing the bearing at low cost. Further, as a result of experiments conducted by the present inventors, it was not always possible to obtain a bearing having a long rolling contact fatigue life even if a bearing element component was manufactured by using the steel described in this publication as a base material.

Japanese Unexamined Patent Publication No. 6-264186 discloses Mn.
"Bearing steel excellent in retardation property of microstructure change due to repeated stress load" containing 2.0 to 5.0% by weight is disclosed. However, if the steel proposed in the above publication containing a large amount of Mn is used as a base material, a large amount of austenite remains after quenching and tempering, which results in a large dimensional change over time when the bearing is used. Further, there is a problem that the finish workability of grinding and polishing, which is a manufacturing process of the bearing element parts, deteriorates.

In JP-A-61-272349, C: 0.8 to 1.2% and S + P: 0.010% by weight.
The following high carbon chromium-based "bearing steels" have been proposed. However, the extreme reduction of the S + P amount has a problem that the finish workability of grinding and polishing, which is a manufacturing process of the bearing element parts, deteriorates.

In Japanese Patent Laid-Open No. 1-306542, it is regulated that O: 0.0005% or less and Ti: 0.002% or less by weight, and "bearing steel with controlled inclusion composition" in the steel.
Is disclosed. However, in order to control the composition of inclusions, particularly in order to reduce O (oxygen) in steel,
Installation of expensive melting equipment, drastic remodeling of conventional equipment, and special technology are required, which increases the cost of the base material.

[0011]

An object of the present invention is to use inexpensive steel as a base material, to easily form it into a desired shape, to reduce the dimensional change during use, and to prevent damage due to rolling fatigue. It is to provide a bearing element component having excellent durability and a method for manufacturing the same.

[0012]

As described above, for the bearing element parts, the JIS standard SUJ2 which has been tempered at a low temperature after quenching has been mainly used. Its structure is composed of spherical carbides (spherical cementite) and martensite remaining during heating during quenching, and austenite that did not transform during quenching and did not decompose during tempering (hereinafter simply referred to as "residual austenite"). . Of these structures, it is known that retained austenite has a great influence on rolling fatigue life, and an increase in the amount thereof up to a certain degree improves rolling fatigue life. On the other hand, heat treatment Vol. 17 No. 4 (1977) 2
It is also reported on pages 31 to 235 that when the amount of retained austenite increases, dimensional changes during use of the bearing become large and smooth rotational movement becomes impossible, resulting in problems in use.

In order to solve the above-mentioned problems, the inventors of the present invention have based on the above-mentioned known basic knowledge, the chemical composition of the steel material as the base material of the bearing element part, the structure of the bearing element part and As a result of research on the heat treatment method, the following findings were obtained.

In a bearing element component made of a base material of a specific component system, the structure after quenching and tempering is made of martensite, spherical carbide and retained austenite, and the area ratio of the retained austenite is 5 to 5. 1
Only in the case of 5%, resistance to rolling fatigue can be enhanced without deteriorating the dimensional stability, in other words, without causing a large dimensional change.

When the area ratio of retained austenite is in the range of, if the content of Mn among the constituent elements is strictly adjusted, the content of the impurity elements P, S and O is not particularly reduced. In addition, the resistance to rolling contact fatigue can be greatly improved.

Like C and Ni, Mn is an element that increases the amount (area ratio) of retained austenite after quenching and tempering, but the improvement in rolling contact fatigue life is based on this increase in the amount of retained austenite. Not only that, but the effect of Mn itself is great. That is, the inventors
Then, using a steel having C: 1.0%, Si: 0.2%, and Cr: 1.0% as base components, the heat treatment conditions and the Mn content are variously changed, and the structure is martensite or spherical. The rolling fatigue test was carried out under the conditions described in detail in later examples, with the carbide and the retained austenite being adjusted so that the amounts (area ratio) of the retained austenite were almost equal. As a result, the Mn content was more than 1.15% by weight and 2.
It has been found that steels up to 0% have better rolling fatigue life than steels with Mn content outside this range.

Mn content exceeds 1.15 to 2.0% by weight
In the steel No. 1, the amount of retained austenite (area ratio) may be controlled by controlling the heating temperature range for quenching and the tempering temperature range.

The present invention based on the above-mentioned findings has the gist of the following bearing element component (1) and its manufacturing method (2).

(1) The base material, in% by weight, C: 0.7 to
1.2%, Mn: 1.15% over 2.0%, C
r: 0.3 to 1.6%, Nb: 0 to 0.1%, V: 0
0.2%, Si: less than 0.4%, P: 0.02% or less,
S: 0.02% or less, P + S: 0.01% to 0.04%, O: 0.0005% to 0.002
A steel having a chemical composition of 0% to the balance Fe and unavoidable impurities, the structure after quenching and tempering is composed of martensite, spherical carbides and retained austenite, and the area ratio of the retained austenite is 5 to 15%. Bearing element parts characterized in that

(2) Steel having the chemical composition described in (1) above is spheroidized and annealed, and then formed into parts, and then 750 to 8
It is heated to 20 ° C. and quenched, and further tempered at a temperature of 100 to 200 ° C., and the structure after quenching and tempering is martensite, spherical carbide and retained austenite, and the area ratio of the retained austenite is 5 to 15 %, And the method for manufacturing a bearing element component according to (1) above.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Each requirement of the present invention will be described in detail below. In addition, “%” of the component content is “% by weight”.
Means

(A) Chemical Composition of Base Material (Steel) C: C increases the hardness of martensite in the mixed structure of martensite, spheroidal carbide and retained austenite, and optimizes the amount of retained austenite, It has the effect of improving rolling fatigue life. But C
If the content of is less than 0.7%, the effect of addition is poor. On the other hand, if it exceeds 1.2%, during cooling during steel ingot casting, and further during cooling of the steel slab after hot working such as hot rolling or hot forging (hereinafter, referred to as “steel ingot”, “steel ingot”). The "piece" is also referred to simply as "steel material", and mesh-like carbides (mainly cementite) are generated at the austenite grain boundaries. This network carbide cannot be easily removed even if the steel material is subjected to soaking or normalizing, which deteriorates the rolling fatigue life of the final product (bearing). In addition, if the C content exceeds 1.2%, it becomes difficult to spheroidize the carbide in the spheroidizing annealing described later, and the rolling fatigue life of the product deteriorates. Therefore, the content of C is set to 0.7 to 1.2%. The C content is preferably 0.9 to 1.1%.

Mn: Mn is an extremely important element in the present invention. That is, when Mn is contained in an appropriate amount, it has an effect of increasing resistance to rolling contact fatigue. The appropriate amount is more than 1.15 to 2.0% as described above, and sufficient rolling contact fatigue resistance cannot be ensured even if the content is less than this amount or the content is more than that. Furthermore, the Mn content is 2.
If it exceeds 0%, especially in the case of a high carbon steel having a C content of more than 1.1%, the amount of retained austenite becomes remarkably large, and the change in product dimensions with time becomes large. Further, the finish workability of grinding and polishing, which is a manufacturing process of the bearing element parts, deteriorates. Therefore, the Mn content is set to more than 1.15% and up to 2.0%. The preferable content of Mn is 1.2 to 1.9%.

Cr: Cr is an element effective for enhancing the hardenability of steel and forming a desired structure. However, if the content is less than 0.3%, the effect of addition is poor. On the other hand, 1.6
Even if it is contained in excess of%, the effect is saturated and the cost increases. Further, since the carbide is stabilized, the carbide precipitated in the mesh shape cannot be removed even by soaking (soaking), which sometimes causes deterioration of rolling contact fatigue characteristics. Therefore, the content of Cr is 0.3 to 1.
6%. The Cr content is preferably 0.5 to 1.5%.

Nb: Nb may not be added. If added, it has a function of forming a carbonitride and suppressing the growth of austenite crystal grains during heating during quenching, and refining the structure after quenching to improve the rolling fatigue life. In order to surely obtain this effect, the content of Nb is preferably set to 0.01% or more. However, if the content exceeds 0.1%, the amount of carbonitrides formed becomes too large and the amount of dissolved C in the matrix decreases, so the amount of retained austenite decreases and it becomes impossible to secure the desired amount. On the contrary, the rolling fatigue characteristics are deteriorated. Therefore, the content of Nb was set to 0 to 0.1%.

V: V may not be added. If added, similar to the above Nb, it has the effect of forming a carbonitride and suppressing the growth of austenite crystal grains during quenching and heating, and refining the structure after quenching to improve the rolling fatigue life. In order to ensure this effect, it is preferable that the content of V is 0.05% or more. However, if the content exceeds 0.2%, the amount of carbonitrides formed becomes too large and the amount of solid solution C in the matrix decreases, so the amount of retained austenite decreases and it becomes impossible to secure the desired amount. On the contrary, the rolling fatigue characteristics are deteriorated. Therefore, the content of V is 0 to
It was set to 0.2%.

Si: Si, which is solid-dissolved in the matrix, increases the hardness, increases the deformation resistance during cold forging which is a manufacturing process of bearing element parts, and deteriorates cold forgeability. In particular, if the content is 0.4% or more, the cold forgeability is greatly reduced, and the life of the die is significantly reduced. Therefore, the Si content is set to less than 0.4%. The preferable Si content is 0.3% or less.

P: P lowers the toughness of the steel and shortens the rolling fatigue life. In particular, its content is 0.0
If it exceeds 2%, the toughness and rolling fatigue properties are significantly deteriorated. Therefore, the upper limit of the P content is set to 0.02%.
The P content is preferably 0.015% or less. However, the small amount of P also has a preferable effect of facilitating finish processing by grinding or polishing steel.

S: S also lowers the toughness of steel and shortens the rolling fatigue life. Especially, its content is 0.02%
If it exceeds, the toughness and rolling fatigue characteristics are significantly deteriorated. Therefore, the upper limit of the S content is set to 0.02%. In addition,
The S content is preferably 0.015% or less.
However, the small amount of S also has a preferable effect of facilitating finish processing by grinding or polishing steel.

P + S: The amount of P + S, which is the sum of the contents of P and S as impurity elements, not only affects the toughness and rolling fatigue life of steel, but also grinding and polishing, which are manufacturing processes of bearing element parts. Affects the finishing processability of. That is, if this value is 0.01% or less, the finish workability of grinding or polishing is greatly deteriorated. On the other hand, if it exceeds 0.04%, the toughness and rolling fatigue characteristics are significantly deteriorated. Therefore, the amount of P + S is set to more than 0.01% and 0.04%. The P + S amount is preferably more than 0.01% and 0.03%.

O: O forms an alumina-based inclusion,
Rolling fatigue characteristics are deteriorated. In particular, when the content exceeds 0.0020%, the rolling fatigue life is significantly reduced. On the other hand, in order to make the O content extremely low, it is necessary to install expensive melting equipment, to drastically modify the conventional equipment, and to use a special technique, which increases the cost of the base material. The O content that can be reduced by ordinary techniques and equipment is more than 0.0005%. Therefore, the O content should be 0.0005.
% To 0.0020%. The upper limit of the O content is preferably limited to 0.0015%.

Base metal (material steel) having the above chemical composition
Is, for example, subjected to soaking, hot rolling or forging, then spheroidizing annealed, is roughly formed into a desired shape by cold forging, is then subjected to quenching and tempering, and is further ground or polished. It is machined and finished into the desired precise element part shape.

(B) Microstructure after quenching and tempering In order to impart a long rolling contact fatigue life to a rolling bearing, not only the chemical composition of the material steel of the bearing element parts is adjusted, but also the microstructure is plastically deformed by a high contact surface pressure. Must be able to withstand. Further, since the rolling bearing is a precision machine part, it is necessary to have a structure excellent in dimensional stability. On the other hand, for precise finishing, it is also necessary to have a structure with high machinability during machining performed after quenching and tempering at low temperature.

That is, by strictly adjusting the chemical composition of the raw steel and defining the structure of the bearing element parts, it is possible to impart a long rolling contact fatigue life to the rolling bearing which is a precision machine part.

Therefore, in the present invention, in addition to the chemical composition of the base material (A), the structure after quenching and tempering is defined as a mixed structure of martensite, spheroidal carbide and retained austenite. This is because in the bearing element component made of the base material having the chemical composition described in (A) above, quenching,
Only when the structure after tempering is composed of martensite, spheroidal carbide and retained austenite, and the area ratio of the retained austenite is 5 to 15%,
This is because the resistance to rolling fatigue can be increased without deteriorating the dimensional stability, in other words, without causing a large dimensional change, and more favorable machinability can be obtained.

In the above-mentioned mixed structure, particularly, only the amount (area ratio) of retained austenite is strictly defined. The reason is that if the area ratio of retained austenite is less than 5%, rolling fatigue life is remarkably reduced, while This is because if it exceeds%, a large dimensional change with time occurs, and the dimensional tolerance of the JIS standard is exceeded.

The amount (area ratio) of martensite and spheroidal carbide need not be particularly limited.

(C) Heat treatment Spheroidizing annealing is an essential treatment for ensuring cold forgeability in cold forging, which is a manufacturing process of bearing element parts, and machinability during machining for precision finishing. Is. The spheroidizing annealing is not particularly limited and may be a usual method.

The heating temperature for quenching must be 750 to 820 ° C. When the quenching heating temperature is lower than 750 ° C., ferrite in the structure before quenching (structure after spheroidizing annealing) remains in the matrix, so that the desired structure described in (B) is not obtained, and the rolling fatigue life is reduced. Markedly reduced. On the other hand, if the quenching heating temperature exceeds 820 ° C., the solid solution of the spherical carbide in the structure before quenching will be too much in the matrix, and the amount of solid solution C will be too much. Therefore, the area ratio of retained austenite is defined by (B) It greatly exceeds the amount that I did.

The tempering must be so-called "low temperature tempering" at 100 to 200 ° C. If the tempering temperature is less than 100 ° C, the recovery of the toughness of martensite is insufficient and the impact strength becomes low. On the other hand, if the temperature exceeds 200 ° C., the decomposition of the retained austenite proceeds, and the hardness also decreases. For this reason, the rolling fatigue life is significantly reduced.

[0041]

EXAMPLE Steels having the chemical compositions shown in Tables 1 and 2 were vacuum-melted by 150 kg by a usual method. Steels A1 to A9 in Table 1
Is a steel of the present invention (hereinafter referred to as the present invention steel). On the other hand, the steels B1 to C2 in Table 2 are comparative steels in which any of the components is out of the range specified by the present invention. Steel among comparison steels
C1 is equivalent to JIS standard SUJ2, and steel C2 is a conventional high Si-high Ni steel that is said to have a long rolling contact fatigue life.

[0042]

[Table 1]

[0043]

[Table 2]

Next, the steel materials of these steels are soaked at 1250 ° C., and then 1250-100.
Hot forged in the temperature range of 0 ℃, diameter 65mm and 20mm
It was a round bar.

Further, spheroidizing annealing is performed by a usual method. A round bar having a diameter of 65 mm has a diameter of 60 mm and a thickness of 6 mm, and a round bar having a diameter of 20 mm has a diameter of 11 m.
A blank having a length of 110 mm and a length of 110 mm was cut out.

(Example 1) Using the steels A3 to A5 which are steels of the present invention as base materials, the above-mentioned raw materials having diameters of 60 mm and 11 mm were prepared.
Heat to 740-860 ° C and then oil quench, then 1
Tempering was performed at 80 ° C. for 2 hours.

A rolling fatigue test piece having a diameter of 60 mm and a thickness of 5 mm was obtained from the heat-treated raw material having a diameter of 60 mm, and the dimensional change measurement shown in FIG. 1 was made from the raw material having a diameter of 11 mm. Test pieces were prepared and subjected to a rolling fatigue test and a dimensional change test, respectively.

The rolling fatigue test was conducted using a thrust type rolling fatigue tester under load conditions with a maximum contact surface pressure of 560 kgf / mm ² and a rotation speed of 1200 rpm. Table 3 shows the detailed conditions of the rolling fatigue test. The rolling fatigue test results are
The L ₅₀ life, which was plotted on a Weibull distribution probability paper and showed a 50% cumulative failure probability, was defined as “rolling fatigue life”.

[0049]

[Table 3]

On the other hand, in the dimensional change test, the test piece
The rate of change was determined by holding the sample in a furnace at 0 ° C. for 2500 hours and measuring the length before and after the treatment with a universal length measuring machine.

Further, the rolling fatigue test piece was used to measure the amount of surface retained austenite (area ratio) by a usual X-ray diffraction method. In addition, a microstructure observation by optical microscope observation was also carried out.

Table 4 shows the test results. In addition, regarding the structure of Table 4, it is meant that the portion (area ratio) other than the retained austenite is martensite and spherical carbide.

From Table 4, even when the steels of the present invention of A3 to A5 are used as the base material, the properties are inferior if the heating temperature for quenching is out of the regulation of the present invention. That is, when the quenching heating temperature is as low as 740 ° C., the amount of retained austenite is only 0 to 3% in area ratio, and therefore the rolling fatigue life is short. On the other hand, when the quenching heating temperature is as high as 860 ° C., the rolling fatigue life is improved, but the dimensional change is large because the retained austenite amount is as high as 18 to 21%.

On the other hand, when the heating temperature for quenching is 780 ° C. and 820 ° C., which are within the ranges specified in the present invention, the rolling fatigue life is as long as 5.1 × 10 ⁷ or more and the dimensional change is large. Is as small as 0.008% or less.

[0055]

[Table 4]

(Example 2) Steels A1 to A9 which are steels of the present invention,
Based on steels B1 to C2 which are comparative steels, the diameter is 60m.
The m and 11 mm blanks were heated to 820 ° C., oil-quenched, and then tempered at 180 ° C. for 2 hours.

After that, the rolling fatigue test piece having the above-mentioned dimensions and FIG.
A test piece for dimensional change measurement shown in 1 was prepared, and a rolling fatigue test and a dimensional change test were performed under the same conditions as in Example 1 above. Amount of retained austenite by X-ray diffraction method (area ratio)
And the microstructure observation by optical microscope observation.

Table 5 shows the results. Regarding the structure shown in Table 5, the parts (area ratio) other than the retained austenite were martensite and spheroidal carbide except for the steel B2. on the other hand,
Non-spheroidized carbides were also found in Steel B2. Also, L
_{The 50} life is described as "rolling fatigue life".

In the case where the steel of the present invention is used as the base material, the amount of retained austenite specified in the present invention is used in all cases, the rolling fatigue life exceeds 5.0 × 10 ⁷ , and the conventional steels C1 and C2 are used.
It is longer than the base material. In the steel of the present invention containing Nb and / or V, the rolling fatigue life tends to be improved. Further, when the steel of the present invention is used as the base material, the dimensional change is a small value of 0.009% or less.

On the other hand, when steels B1 to B10, which are comparative steels, are used as the base metal, one of rolling fatigue life and dimensional stability, as compared with the case where the steel of the present invention is used as the base metal, Or both are inferior.

Steel B1 has a C content lower than the value specified in the present invention, and therefore, when this is used as the base material, the rolling fatigue life is short.

Steel B2 has a C content higher than the value specified in the present invention, and non-spheroidized carbides are present. When this is used as a base material, rolling fatigue life is short.

Steel B3 has a higher Mn content and a lower Cr content than the values specified in the present invention. Moreover, the amount of retained austenite is as large as 22%. Therefore, when this is used as the base material, the dimensional stability is poor and the rolling fatigue life is short.

On the contrary, in steel B4, the Mn content is lower and the Cr content is higher than the values specified in the present invention. Therefore, when this is used as the base material, the rolling fatigue life is short.

Steel B5 has P, which is higher than the value specified in the present invention.
Higher S, P + S and O contents. Therefore, when this is used as the base material, the rolling fatigue life is short.

Steel B6 has V and N higher than the values specified in the present invention.
The content of b is high. Therefore, the amount of retained austenite does not reach the value specified in the present invention, and when this is used as the base material, the rolling fatigue life is short.

Steels B7 and B8 each have a higher Nb and V content than the values specified in the present invention, and the residual austenite amount does not reach the value specified in the present invention. Therefore, rolling fatigue life is short when these steels are used as base materials.

Steels B9 and B10 respectively have higher P and S contents than the values specified in the present invention. Therefore, rolling fatigue life is short when these steels are used as base materials.

[0069]

[Table 5]

[0070]

INDUSTRIAL APPLICABILITY The bearing element component of the present invention is made of inexpensive steel as a base material, is easily formed into a desired shape, has a small dimensional change during use, and has a long rolling contact fatigue life. It can be used as an element component of rolling bearings such as ball bearings and roller bearings used in industrial machines and automobiles. This bearing element component can be manufactured relatively easily by the method of the invention described above.

[Brief description of drawings]

FIG. 1 is a view showing a dimensional change measuring test piece used in Examples.

Claims (2)

[Claims] 1. A base material, in% by weight, C: 0.7 to 1.2.
%, Mn: 1.15% to 2.0%, Cr: 0.
3 to 1.6%, Nb: 0 to 0.1%, V: 0 to 0.2
%, Si: less than 0.4%, P: 0.02% or less, S:
0.02% or less, and P + S: more than 0.01% and 0.
Up to 04%, O: 0.0005% over 0.0020%
In the steel having a chemical composition of residual Fe and unavoidable impurities, the structure after quenching and tempering is composed of martensite, spherical carbide and retained austenite, and the area ratio of the retained austenite is 5 to 15%. Characteristic bearing element parts. 2. A steel having the chemical composition according to claim 1 is spheroidized and annealed, then formed into a component, then heated to 750 to 820 ° C. to be quenched, and further tempered at a temperature of 100 to 200 ° C. The manufacturing of a bearing element component according to claim 1, wherein the structure after quenching / tempering is martensite, spherical carbide and retained austenite, and the area ratio of the retained austenite is 5 to 15%. Method.