JP4343357B2 - Rolling bearing parts for high temperature - Google Patents

Description

【００３７】
＜硬さ調査＞
焼入れ後の焼戻し硬さおよび浸炭窒化処理後の焼戻し硬さを測定するために、直径５０ｍｍの素材から直径２０ｍｍ、長さ１００ｍｍの円柱状の試験片を機械加工によって作製した。
【００３８】
焼入れ処理は、ソルト炉による加熱を行ない、８５０℃に３０分均熱した後、８０℃の油中に焼入れることで行なった。この後に、焼戻し処理として同じくソルト炉で加熱を行ない、３５０℃で２時間保持した後に空冷する焼戻し処理を行なった。
【００３９】
また浸炭窒化処理は通常の生産工程で使用されているガス雰囲気炉を用い、ＲＸガス雰囲気中で炭素ポテンシャルを１．０〜１．２％、ＮＨ₃ の添加量を５〜１０％として８５０℃に６０分保持した後、油中に焼入れた。その後、３５０℃で１２０分の焼戻しを行なった。
【００４０】
この焼入れ焼戻し処理を施した試験片または浸炭窒化処理後に焼戻し処理を施した試験片の中央部から厚さ１０ｍｍの円盤型の試験片を切断し、両面を湿式の研磨加工によって研磨し、硬さ測定用の試験片を作製した。
【００４１】
硬さはロックウェル硬さ計を使用し、試験片の断面において表面から２ｍｍ深さの位置の硬さ測定を行ない、７点の平均値を焼戻し硬さとして求めた。
【００４２】
＜転動疲労寿命試験＞
軸受部品として性能を確認するために、スラスト型の転動疲労寿命試験機によって疲労試験を行ない、各材料の寿命評価を実施した。
【００４３】
寿命評価に用いた試験片は、直径５０ｍｍの丸棒素材から機械加工によって外径４７ｍｍ、内径２９ｍｍおよび厚さ７ｍｍのリング状のスラスト型転動疲労寿命試験片を粗加工した。
【００４４】
粗加工を完了した試験片の熱処理として、焼入れ焼戻し処理および浸炭窒化処理を施した。処理は、通常の生産工程で使用されている実炉を用いた。
【００４５】
焼入れ焼戻し処理については、ガス雰囲気炉を用い、ＲＸガス雰囲気中で各鋼の炭素量をベースに脱炭や浸炭が起こらないように炭素ポテンシャルを制御しながら８５０℃に３０分保持した後、油中に焼入れた。その後、３５０℃で１２０分の焼戻しを行なった。
【００４６】
浸炭窒化処理は上記の硬さ試験片と同条件で熱処理を行なった。
熱処理完了の後に、試験片の両面を研磨加工し鏡面状態に仕上げた。なお、浸炭窒化処理した試験片では、研磨加工時の加工代を両面とも０．１ｍｍとした。
【００４７】
転動疲労寿命試験は、スラスト型転動疲労寿命試験機によって実施した。なお、表２にその試験の諸条件を示す。試験は、常温環境下および２００℃環境下で実施し、さらに異物の混入環境を再現した環境下でも試験を行なった。
【００４８】
【表２】

【００４９】
疲労試験は、同一条件で１５回の繰返し試験を行ない、ワイブル確率における累積損傷確率が１０％となる寿命を各材料の寿命として判定した。なお、表１における比較例Ｎｏ．１４は汎用のＳＵＪ２であり、この焼入れ焼戻し処理材の寿命を１．０とした場合の比率で各材料の寿命値を記述した。
【００５０】
＜炭化物＞
鋼中に存在する炭化物の測定には、スラスト型転動疲労寿命試験片を使用した。各種の熱処理を実施してスラスト型転動疲労寿命試験片に加工された試験片において、リング横断面を切断し、組織観察用のミクロ試験片を製造した。この試験片を鏡面仕上げし、さらに炭化物の観察を行なうために、ピクラル腐食液によって腐食した。このミクロ試料において、転動面の表層から０．１ｍｍ深さにおける炭化物の観察を光学顕微鏡で実施し、視野面積５０ｍｍ² における最大の炭化物を測定した。
【００５１】
上記の３５０℃焼戻し硬さ、常温および２００℃での転動疲労寿命、異物混入条件下での転動疲労寿命および最大炭化物寸法の結果を表３および表４に示す。
【００５２】
【表３】

【００５３】
【表４】

【００５４】
上記の表３および表４の結果より、本発明の組成範囲を有する本発明例では、３５０℃の焼戻し処理を施しても、硬さがＨＲＣ５８以上となることが判明した。また、本発明例では、単なる焼入れ焼戻し処理（ＨＴ）を施した場合でも、比較例に比べて２００℃での転動疲労寿命および異物条件下における転動疲労寿命が高くなることが判明した。また、焼入れ処理に代えて浸炭窒化処理を施した場合でも、優れた転動疲労寿命が得られることも判明した。また、本発明例では、転動面の表層から０．１ｍｍ深さにおける炭化物の最大寸法が８．０μｍ以下になることが判明した。
【００５５】
今回開示された実施例は全ての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【００５６】
【発明の効果】
以上に説明したように本願発明者らが最適な組成元素およびその含有量を見出したことにより、焼入れ焼戻し処理をすることで、浸炭窒化処理を施さなくとも異物混入条件下で優れた転動疲労寿命が得られるとともに、高温（たとえば３５０℃）で焼戻し処理を施しても高い硬度を得られる安価な高温用転がり軸受部品を得ることができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to rolling bearing parts used in power transmission devices and engine parts of automobiles, airplanes, ships, industrial machines, and the like, and more specifically, in an environment in which foreign matters such as dust and dust are mixed and the temperature of the atmosphere. Relates to an inexpensive high-temperature rolling bearing part having an excellent rolling fatigue life even in an environment of room temperature to 300 ° C.
[0002]
[Prior art]
Rolling bearings used in power transmission parts and engine parts of automobiles, aircraft, ships, industrial machines, etc. are used in harsh environments, and even in such environments they have excellent rolling fatigue life. Reliability and reliability are required. In particular, the rolling bearings used above may contain foreign matter such as dust, debris and iron powder. Under these circumstances, the rolling fatigue life will be significantly reduced compared to the use in a clean environment. It has been known. As a countermeasure, in recent years, a high carbon chromium bearing steel such as SUJ2 and case hardening steel such as SCM420, SNCM420, and SNCM815 are subjected to carbonitriding to generate an appropriate amount of retained austenite directly under the rolling surface. The service life is improved when foreign matter is mixed.
[0003]
However, a general carbonitriding process is a longer process than a quenching and tempering process applied to SUJ2 steel and the like. For this reason, these carbonitrided rolling bearings have problems such as a significant increase in manufacturing costs compared to rolling bearings manufactured in a normal quenching and tempering process.
[0004]
In addition, since rolling bearings used in automobiles, aircrafts, and the like are used in a high temperature environment, excellent rolling fatigue life characteristics are required in an extremely harsh environment such as a foreign matter mixed environment and a high temperature environment. In general, rolling bearings used at high temperatures have dimensional stability after quenching high carbon chrome bearings such as SUJ2 or carburizing and quenching hardened steels such as SCM420 and SNCM815. In order to obtain, the tempering process is implemented at the high temperature of 300 degreeC or more.
[0005]
However, when these materials are tempered at a high temperature, the hardness is greatly reduced, so that the predetermined hardness required for the rolling bearing cannot be obtained, and the rolling fatigue life and wear resistance are lowered. For this reason, precipitation hardened steel materials such as M50 are used for bearing steels used in high temperature regions, but such steel materials have high manufacturing costs and material costs, and the range of use is limited. The above-mentioned needs could not be met.
[0006]
Further, in a rolling bearing subjected to carbonitriding, residual austenite is generated immediately after the heat treatment and nitrogen penetrates into the steel. This residual austenite relieves stress concentration due to foreign matter contamination, and further, the temper softening resistance is improved by the action of nitrogen that has penetrated into the steel, and the structural changes that occur during the rolling fatigue are suppressed. Thus, the rolling fatigue life is improved.
[0007]
However, when applied to a high temperature rolling bearing, it is necessary to perform high temperature tempering in order to ensure dimensional stability as described above. When this high temperature tempering is performed, the retained austenite is decomposed and the amount thereof is reduced. Therefore, the effect cannot be expected, and there is a limit in preventing temper softening by nitrogen. Sufficient performance cannot be obtained in a high-temperature environment in which is mixed.
[0008]
In recent years, in the field of automobiles and the like, high output and downsizing of engines are rapidly progressing, but at the same time, the usage environment of rolling bearings is increasing under more severe conditions. The operating temperature range of the rolling bearing used in the engine section is about 130 ° C. at the normal temperature, but it is expected that the temperature rises to 160 ° C. instantaneously. Today, with the increase in engine output, the operating temperature range of rolling bearings is expected to rise to about 160 ° C. at the normal temperature, and instantaneously exceed 200 ° C. Therefore, in the future, when higher output and lighter weight of the engine are promoted, it is expected that an improvement in rolling fatigue life in a foreign matter mixed environment and a high temperature environment is required.
[0009]
However, current high carbon chrome bearing steel and rolling bearings that have been carburized or carbonitrided do not have sufficient heat resistance. The life cannot be maintained. In addition, precipitation hardened bearing steel such as M50 has a problem such as high cost, and is in a situation where it is not possible to provide a rolling bearing that is inexpensive and excellent in rolling fatigue life characteristics.
[0010]
[Problems to be solved by the invention]
The present invention has been made to solve the above problems, and has excellent rolling fatigue life even in a foreign matter mixed environment and a high temperature environment, and is inexpensive for high temperatures. An object is to provide rolling bearing parts.
[0011]
[Means for Solving the Problems]
As a result of diligent study, the inventors of the present application have found that a combination of composition elements capable of obtaining an inexpensive rolling bearing part for high temperature having an excellent rolling fatigue life in a foreign matter-mixed environment as well as in a high temperature environment, each content thereof, The tempering hardness and the maximum carbide size were found.
[0012]
Therefore, a high-temperature rolling bearing part according to one aspect of the present invention is a high-temperature rolling bearing part having an inner ring, an outer ring, and a rolling element, and at least one of the inner ring, the outer ring, and the rolling element contains an alloy element. The amount is mass%, C (carbon) is 0.6% to 1.3%, Si (silicon) is 0.76 % to 3.0%, and Mn (manganese) is 0.2% to 1. 5% or less, P (phosphorus) 0.03% or less, S (sulfur) 0.03% or less, Cr (chromium) 0.5% to 3.0%, Mo (molybdenum) 0.05 % To less than 0.25%, Al (aluminum) 0.050% or less, Ti (titanium) 0.003% or less, O (oxygen) 0.0015% or less, N (nitrogen) 0.015% Including the following, the balance being made of steel consisting of Fe (iron) and inevitable impurities, and It has a structure that has been tempered after quenching or carbonitriding, has a hardness after tempering of not less than HRC58, and has a maximum carbide size of not more than 8 μm.
[0013]
A high temperature rolling bearing component according to another aspect of the present invention is a high temperature rolling bearing component having an inner ring, an outer ring and a rolling element, wherein at least one of the inner ring, the outer ring and the rolling element has an alloy element content. Is mass%, C (carbon) is 0.6% to 1.3%, Si (silicon) is 0.76 % to 3.0%, and Mn (manganese) is 0.2% to 1.5%. %, P (phosphorus) 0.03% or less, S (sulfur) 0.03% or less, Cr (chromium) 0.5% to 3.0%, Mo (molybdenum) 0.05% More than less than 0.25%, Al (aluminum) 0.050% or less, Ti (titanium) 0.003% or less, O (oxygen) 0.0015% or less, N (nitrogen) 0.015% or less It is made of a steel material that contains at least each element and the balance is made of Fe (iron). It has a structure that has been tempered after pouring or carbonitriding, has a hardness after tempering of not less than HRC58, and has a maximum carbide size of not more than 8 μm.
[0014]
In another aspect of the present invention, B (boron), W (tungsten), or other elements may be included in addition to the listed elements.
[0015]
The rolling bearing part for high temperature according to one and other aspects of the present invention has the above composition, and therefore, when subjected to quenching and tempering treatment, it has excellent rolling fatigue life in an environment containing foreign matter without performing carbonitriding treatment. Is obtained. For this reason, since carbonitriding can be omitted, the manufacturing cost can be reduced.
[0016]
As described above, it is desirable to omit the carbonitriding process from the viewpoint of reducing the manufacturing cost. However, even if the carbonitriding process is performed in place of the quenching process, an excellent rolling fatigue life can be obtained in a foreign matter mixed environment.
[0017]
Moreover, since it has the said composition, even if it performs tempering process at high temperature (for example, 350 degreeC), high hardness with HRC58 or more can be obtained. Thus, the amount of retained austenite can be reduced by performing tempering treatment at a high temperature, so that dimensional stability under a high temperature environment can be obtained and high hardness of HRC58 or higher can be obtained. For this reason, the rolling fatigue life and wear resistance in a high temperature environment can be improved as compared with the conventional example.
[0018]
Further, steel having the above composition is less expensive than precipitation hardening type bearing steel such as M50.
As described above, it is possible to obtain an inexpensive rolling bearing component for high temperature that has an excellent rolling fatigue life in a foreign matter mixed environment and a high temperature environment.
[0019]
In addition, it is preferable that the tempering process temperature is 180 degreeC or more and 350 degrees C or less. Since the rolling bearing is usually used at a temperature of about 100 ° C., the tempering temperature needs to be 180 ° C. or higher.
[0020]
Hereinafter, the reasons for limiting the chemical components of the high-temperature rolling bearing part of the present invention will be described.
[0021]
(1) C content (0.6% or more and 1.3% or less) C is an essential element for securing strength as a rolling bearing, and for maintaining the hardness after a predetermined heat treatment. Since it is necessary to contain 0.6% or more, the lower limit of the C content is limited to 0.6%. In the present invention, as described later, carbides play an important role in the rolling fatigue life. However, when the C content exceeds 1.3%, large carbides are formed, and rolling fatigue occurs. Since it was found that the lifetime was reduced, the upper limit of the C content was limited to 1.3%.
[0022]
(2) About Si content (0.3% or more and 3.0% or less) It is desirable to add Si because it suppresses softening in a high temperature range and improves the heat resistance of the rolling bearing. However, since the effect cannot be obtained if the Si content is less than 0.30%, the lower limit of the Si content is limited to 0.30%. Moreover, although heat resistance improves with increase in Si content, since the effect will be saturated even if it contains a large amount exceeding 3.0%, hot workability and machinability will fall. The upper limit of Si content was limited to 3.0%.
[0023]
(3) About Mn content (0.2% or more and 1.5% or less) Mn is an element used for deoxidation when manufacturing steel, and is an element that improves hardenability. In order to obtain it, since it is necessary to add 0.2% or more, the minimum of Mn content was limited to 0.2%. However, if Mn is contained in a large amount exceeding 1.5%, the machinability is greatly lowered, so the upper limit of the Mn content is limited to 1.5%.
[0024]
(4) P content (0.03% or less) P segregates at the austenite grain boundaries of the steel and causes a decrease in toughness and rolling fatigue life, so 0.03% was made the upper limit of the content.
[0025]
(5) S content (0.03% or less) S impairs hot workability of steel and forms non-metallic inclusions in the steel to reduce toughness and rolling fatigue life. 03% was made the upper limit of the S content. Further, S has a harmful surface as described above, but also has an effect of improving machinability, so it is desirable to reduce it as much as possible, but if the content is up to 0.005% Permissible.
[0026]
(6) About Cr content (0.5% to 3.0%) Cr is an element that plays an important role in the present invention, for improving hardenability, ensuring hardness by carbide and improving life. To be added. Since addition of 0.5% or more is necessary to obtain a predetermined carbide, the lower limit of the Cr content is limited to 0.5%. However, if Cr is contained in a large amount exceeding 3.0%, large carbides are generated and the rolling fatigue life is reduced, so the upper limit of Cr content is limited to 3.0%.
[0027]
(7) Al content (less than 0.050%) Al is used as a deoxidizer during steel production, but it is reduced because it produces hard oxide inclusions and reduces rolling fatigue life. It is desirable to do. Further, when the Al content exceeds 0.050%, a significant decrease in rolling fatigue life was observed, so the upper limit of the Al content was limited to 0.050%.
[0028]
In order to make the Al content less than 0.005%, the manufacturing cost of the steel increases, so it is preferable to limit the lower limit of the Al content to 0.005%.
[0029]
(8) Regarding Ti content (0.003% or less), O content (0.0015% or less), and N content (0.015% or less), Ti, O and N are oxides in the steel. In order to reduce the fatigue life of rolling by forming nitride and forming non-metallic inclusions as a non-metallic inclusion, Ti: 0.003%, O: 0.0015%, N: 0.015% are the upper limit of each element. It was.
[0030]
(9) About Mo content (0.05% or more and less than 0.25%) Mo improves the hardenability of steel and has the effect of preventing softening during tempering treatment by dissolving in carbide. . In particular, Mo has been added because it has been found to improve the rolling fatigue life at high temperatures. However, if Mo is contained in a large amount of 0.25% or more, the steel material cost increases, and the hardness does not decrease during the softening treatment for facilitating the cutting process, and the machinability is greatly deteriorated. The Mo content was limited to less than 0.25%. Further, if the Mo content is less than 0.05%, there is no effect on carbide formation, so the lower limit of the Mo content is limited to 0.05%.
[0031]
Next, reference will be made to the tempering hardness and carbide of the high temperature rolling bearing part of the present invention.
[0032]
(10) Tempering hardness Bearings used in a high temperature range are generally subjected to tempering treatment at a temperature equal to or higher than the environmental temperature in order to stabilize the dimensions under the usage environment. As a result of conducting a detailed investigation on the tempering hardness and the rolling fatigue life at a temperature environment of 200 ° C., the inventors of the present application found a correlation between the tempering hardness and the rolling fatigue life. It was confirmed that the life tends to show a long life. In particular, when the tempering hardness is the same, a bearing that has been tempered at a higher temperature has a longer life, and a bearing that has a higher tempering hardness even when tempered at a higher temperature has a longer life. It was done. Furthermore, when the hardness after the tempering treatment is less than HRC58, it has been found that the life tends to decrease rapidly, and the life variation increases. In order to improve the life at high temperature and reduce variation, it is necessary to maintain a hardness of HCR 58 or higher, and the higher the tempering temperature at this time, the more preferable.
[0033]
(11) It has been found that the carbide carbide has the effect of improving the rolling fatigue life by maintaining the hardness during the tempering treatment and suppressing the structural change during the rolling fatigue. At this time, as a result of investigating the maximum carbide size and rolling fatigue life at a depth of 0.1 mm from the surface layer of the bearing, there is a tendency for the life to decrease when large carbides exist, and the maximum size is larger than 8 μm. Since it became clear that when the carbides remain, the service life suddenly decreases. Therefore, the maximum size of the carbides is defined as 8 μm.
[0034]
【Example】
Examples of the present invention will be described below.
[0035]
A steel material having the chemical composition shown in Table 1 was melted by a vacuum induction furnace, cast into a steel ingot with a weight of 150 kg, heated and held at 1200 ° C. for 3 hours, and hot forged, A round bar was produced. The round bar material is kept at 850 ° C. for 1 hour as a normalizing treatment, then air-cooled, and further maintained at 790 ° C. for 6 hours as a softening treatment for easy cutting, and then up to 650 ° C. up to 10 ° C. The sample was cooled at a cooling rate of / hour and softened by allowing it to cool to room temperature and used as materials for various investigations.
[0036]
[Table 1]

[0037]
<Hardness investigation>
In order to measure the tempering hardness after quenching and the tempering hardness after carbonitriding, a cylindrical test piece having a diameter of 20 mm and a length of 100 mm was produced by machining from a material having a diameter of 50 mm.
[0038]
The quenching treatment was performed by heating in a salt furnace, soaking at 850 ° C. for 30 minutes, and then quenching in 80 ° C. oil. After this, as a tempering process, heating was similarly performed in a salt furnace, and a tempering process was performed in which air-cooling was performed after holding at 350 ° C. for 2 hours.
[0039]
In addition, carbonitriding is performed at 850 ° C. using a gas atmosphere furnace used in a normal production process, with a carbon potential of 1.0 to 1.2% and an addition amount of NH ₃ of 5 to 10% in an RX gas atmosphere. For 60 minutes and then quenched in oil. Thereafter, tempering was performed at 350 ° C. for 120 minutes.
[0040]
A 10 mm-thick disc-shaped test piece is cut from the center portion of the test piece that has been subjected to quenching and tempering treatment or the test piece that has been subjected to tempering treatment after carbonitriding, and both surfaces are polished by wet polishing to obtain hardness. A test specimen for measurement was prepared.
[0041]
The hardness was measured using a Rockwell hardness tester at a position 2 mm deep from the surface in the cross section of the test piece, and an average value of 7 points was obtained as the tempering hardness.
[0042]
<Rolling fatigue life test>
In order to confirm the performance as a bearing part, a fatigue test was performed by a thrust type rolling fatigue life tester, and the life evaluation of each material was performed.
[0043]
The test piece used for the life evaluation was roughly machined from a round bar material having a diameter of 50 mm by machining into a ring-shaped thrust type rolling fatigue life test piece having an outer diameter of 47 mm, an inner diameter of 29 mm and a thickness of 7 mm.
[0044]
Quenching and tempering treatment and carbonitriding treatment were performed as the heat treatment of the test piece after the rough machining. The actual furnace used in the normal production process was used for the treatment.
[0045]
For quenching and tempering treatment, a gas atmosphere furnace was used, and after holding at 850 ° C. for 30 minutes while controlling the carbon potential so that decarburization and carburization would not occur based on the carbon content of each steel in the RX gas atmosphere, Quenched inside. Thereafter, tempering was performed at 350 ° C. for 120 minutes.
[0046]
Carbonitriding was performed under the same conditions as the above hardness test pieces.
After the heat treatment was completed, both sides of the test piece were polished and finished in a mirror state. In the carbonitrided test piece, the machining allowance during polishing was 0.1 mm on both sides.
[0047]
The rolling fatigue life test was carried out using a thrust type rolling fatigue life tester. Table 2 shows the conditions of the test. The test was carried out in a normal temperature environment and a 200 ° C. environment, and the test was also performed in an environment in which a foreign matter mixed environment was reproduced.
[0048]
[Table 2]

[0049]
The fatigue test was repeated 15 times under the same conditions, and the lifetime at which the cumulative damage probability in the Weibull probability was 10% was determined as the lifetime of each material. In Table 1, Comparative Example No. 14 is a general-purpose SUJ2, and the life value of each material is described in a ratio when the life of the quenched and tempered material is 1.0.
[0050]
<Carbide>
Thrust-type rolling fatigue life test pieces were used to measure carbides present in the steel. In a test piece processed into a thrust type rolling fatigue life test piece by performing various heat treatments, a ring cross-section was cut to produce a micro test piece for structure observation. This specimen was mirror-finished and further corroded with a picral corrosion solution for observation of carbides. In this micro sample, the carbides at a depth of 0.1 mm from the surface layer of the rolling surface were observed with an optical microscope, and the maximum carbides in a visual field area of 50 mm ² were measured.
[0051]
Tables 3 and 4 show the results of the 350 ° C. tempering hardness, the rolling fatigue life at room temperature and 200 ° C., the rolling fatigue life under the foreign matter mixing conditions, and the maximum carbide size.
[0052]
[Table 3]

[0053]
[Table 4]

[0054]
From the results of Tables 3 and 4 above, it was found that in the present invention examples having the composition range of the present invention, the hardness was HRC58 or higher even when tempering at 350 ° C. was performed. Moreover, in the example of this invention, it turned out that the rolling fatigue life in 200 degreeC and the rolling fatigue life in a foreign material condition become high compared with a comparative example, even when performing simple quenching and tempering treatment (HT). It has also been found that an excellent rolling fatigue life can be obtained even when carbonitriding is performed instead of quenching. Moreover, in the example of this invention, it turned out that the maximum dimension of the carbide | carbonized_material in 0.1 mm depth from the surface layer of a rolling surface will be 8.0 micrometers or less.
[0055]
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0056]
【The invention's effect】
As described above, the present inventors have found an optimal composition element and its content, and by performing quenching and tempering treatment, excellent rolling fatigue under the condition of foreign matter mixing without performing carbonitriding treatment An inexpensive high-temperature rolling bearing part that can obtain a long life and obtain a high hardness even when subjected to a tempering treatment at a high temperature (for example, 350 ° C.) could be obtained.

Claims (2)

A high temperature rolling bearing part having an inner ring, an outer ring and rolling elements,
At least one of the inner ring, the outer ring, and the rolling element has an alloy element content of mass%, C is 0.6% or more and 1.3% or less, and Si is 0.76 % or more and 3.0% or less. Mn is 0.2% or more and 1.5% or less, P is 0.03% or less, S is 0.03% or less, Cr is 0.5% or more and 3.0% or less, and Mo is 0.05% or more. Less than 0.25%, Al is 0.050% or less, Ti is 0.003% or less, O is 0.0015% or less, N is 0.015% or less, and the balance is made of steel consisting of Fe and inevitable impurities. And having a structure tempered after quenching or carbonitriding, and having a hardness after the tempering of HRC58 or more and a maximum carbide size of 8 μm or less. Rolling bearing parts. A high temperature rolling bearing part having an inner ring, an outer ring and rolling elements,
At least one of the inner ring, the outer ring, and the rolling element has an alloy element content of mass%, C is 0.6% or more and 1.3% or less, and Si is 0.76 % or more and 3.0% or less. Mn is 0.2% or more and 1.5% or less, P is 0.03% or less, S is 0.03% or less, Cr is 0.5% or more and 3.0% or less, and Mo is 0.05% or more. Steel material comprising less than 0.25%, Al of 0.050% or less, Ti of 0.003% or less, O of 0.0015% or less, N of 0.015% or less and at least each element, and the balance being Fe And having a structure tempered after quenching or carbonitriding, and having a hardness after the tempering of HRC58 or more and a maximum carbide size of 8 μm or less. Rolling bearing parts for high temperatures.