WO2000028102A1 - High-temperature rolling bearing part - Google Patents

Abstract

A high-temperature rolling bearing part which consists of a steel material containing in alloy element mass % at least 0.6 to up to 1.3 % of C, at least 0.3 to up to 3.0 % of Si, at least 0.2 % to up to 1.5 % of Mn, up to 0.03 % of P, up to 0.03 % of S, at least 0.3 to up to 5.0 % of Cr, at least 0.1 to up to 3.0 % of Ni, up to 0.05 % of Al, up to 0.003 % of Ti, up to 0.0015 % of O, up to 0.015 % of N and the remaining components of Fe and unavoidable impurities, and which has a construction obtained by being tempered after hardened or carbonitrided, with a temper hardness of at least HRC 58 and a maximum carbide size of up to 8 νm, whereby a high-temperature rolling bearing part is provided that has an excellent rolling fatigue life even in foreign matter-mixed and high-temperature environments and is less costly.

Description

 Description Rolling bearing parts for high temperature

 The present invention relates to a rolling bearing component used for a power transmission device such as an automobile, an aircraft, a ship, and an industrial machine, and an engine unit, and more specifically, to an environment and an atmosphere where foreign matters such as dust and dirt are mixed. The present invention relates to an inexpensive high-temperature rolling bearing component having an excellent rolling fatigue life even in an environment in which the temperature is from room temperature to 300 ° C. Background art

 Rolling bearings used in power transmission parts and engine parts of automobiles, aircraft, ships, industrial machines, etc. are used in harsh environments. Require reliability and reliability. In particular, in the rolling bearings used above, foreign matter such as dust, dirt, and iron powder may be mixed in, and in such an environment, the rolling fatigue life is significantly reduced as compared with the use in a clean environment. It is known that As a countermeasure, in recent years, high-carbon chromium bearing steel such as SUJ2 and case-hardened steel such as SCM420, SNCM420, and SNCM815 have been subjected to carbonitriding so that The method of generating an appropriate amount of residual austenite is applied, and the life is improved even if foreign matter is mixed.

 However, general carbonitriding is a longer time than quenching and tempering applied to SUJ2 steel and the like. For this reason, these carbonitrided rolling bearings have a problem that the production cost is significantly increased as compared with the rolling bearings manufactured in the usual quenching and tempering process.

In addition, since rolling bearings used in automobiles and aircraft are used in high-temperature environments, they are required to have excellent rolling fatigue life characteristics in extremely contaminated environments and high-temperature environments. ing. Generally, for rolling bearings used at high temperatures, high carbon chromium bearings such as SUJ2 are quenched, or case hardened steels such as SCM420 and SNCM815 are carburized. After obtaining dimensional stability Therefore, tempering is performed at a high temperature of 300 ° C. or more.

 However, when these materials are tempered at high temperatures, their hardness is greatly reduced, and the required hardness required for rolling bearings cannot be obtained, and the rolling fatigue life and wear resistance decrease. . For this reason, precipitation-hardening steel materials such as M50 are used for bearing steels used in high-temperature regions.However, such steel materials have high manufacturing and material costs, and their use range is high. Due to its limitations, it was unable to meet the needs described above.

 In addition, in rolling bearings that have been subjected to carbonitriding, residual austenite is generated immediately below the rolling parts after heat treatment, and nitrogen enters the steel. This residual austenite alleviates the stress concentration due to the inclusion of foreign matter, and further improves the temper softening resistance due to the action of nitrogen that has penetrated the steel, thereby reducing the structural changes that occur during the rolling fatigue process. As a result, the rolling fatigue life is improved. However, when applied to high-temperature rolling bearings, high-temperature tempering must be performed to ensure dimensional stability, as described above. When this high-temperature tempering is performed, the residual austenite is decomposed and its amount is reduced, so that its effect cannot be expected, and there is a limit in preventing temper softening by nitrogen. However, sufficient performance cannot be obtained in a high-temperature environment where foreign substances are mixed.

 In recent years, in the field of automobiles and the like, the output and miniaturization of engines have been rapidly progressing, but at the same time, the use environment of rolling bearings has been increasing under more severe conditions. The operating temperature range of the rolling bearings used in the engine section is about 130 ° C at normal temperature, but it is expected that the temperature will rise instantaneously to 160 ° C. Today, with the increase in engine power, the operating temperature range of rolling bearings is expected to rise to around 160 ° C at normal temperature, and even instantaneously exceed 200 ° C . Therefore, it is expected that if the output and weight reduction of the engine are promoted in the future, the rolling fatigue life under the contaminated environment and high temperature environment will need to be improved.

However, the current high-carbon chromium bearing steels--rolling bearings that have been carburized or carbonitrided do not have sufficient heat resistance, and have sufficient rolling fatigue under the anticipated contaminant environment and high temperature environment. Life cannot be maintained. Also, precipitation like M50 Hardened bearing steel has problems such as high cost, and it is not possible to provide a rolling bearing that is inexpensive and has excellent rolling fatigue life characteristics.

 The present invention has been made in order to solve the above problems, and has excellent rolling fatigue life even in a foreign material mixed environment and a high temperature environment, and is inexpensive as compared with a conventional example. An object of the present invention is to provide a high-temperature rolling bearing component. Disclosure of the invention

 As a result of intensive studies, the inventors of the present invention have found that combinations of compositional elements and their respective components that can provide an inexpensive high-temperature rolling bearing part having excellent rolling fatigue life in a foreign material-contaminated environment and a high-temperature environment. The content was found.

 Therefore, the high-temperature rolling bearing component of the present invention is a component of a high-temperature rolling bearing having an inner ring, an outer ring, and a rolling element, wherein the alloy element content is mass% and c (carbon) is

0.6% or more and 1.3% or less, Si (silicon) 0.3% or more and 3.0% or less, Mn (manganese) 0.2% or more and 1.5% or less, P (phosphorus) 0.0 3% or less, S (sulfur) is 0.03% or less, Cr (chromium) is 0.3% or more and 5.0% or less, Ni

(Nickel) is 0.1% or more and 3.0% or less, A1 (anoremium) is 0.050% or less, Ti (titanium) is 0.03% or less, and O (oxygen) is 0.1% or less. 0.15% or less, N (Nitrogen) is not more than 0.015%, and the balance consists of steel consisting of Fe (iron) and unavoidable impurities, and has been tempered after quenching or carbonitriding It has a structure, hardness after tempering is HRC 58 or more, and maximum carbide size is 8 μm or less.

 Since the high-temperature rolling bearing component of the present invention has the above-described composition, if it is subjected to quenching and tempering, excellent rolling fatigue life can be obtained in a foreign matter-mixed environment without carbonitriding. Therefore, the carbonitriding treatment can be omitted, and the production cost can be reduced.

 As described above, it is desirable to omit carbonitriding from the viewpoint of manufacturing cost reduction. Even if carbonitriding is performed instead of force quenching, excellent rolling fatigue life can be obtained in an environment where foreign substances are mixed.

In addition, since it has the above composition, it is baked at a high temperature (for example, 350 ° C). However, high hardness of HRC 58 or more can be obtained. By performing the tempering treatment at a high temperature in this way, the amount of retained austenite can be reduced, so that dimensional stability in a high-temperature environment can be obtained, and a high hardness of HRC 58 or more can be obtained. Therefore, the rolling fatigue life and wear resistance in a high-temperature environment can be improved as compared with the conventional example.

 Also, steels of the above composition are less expensive than precipitation hardened bearing steels such as M50.

 As described above, it is possible to obtain an inexpensive high-temperature rolling bearing component having excellent rolling fatigue life in a contaminated environment and a high-temperature environment.

 Preferably, the tempering temperature is from 180 ° C to 350 ° C. Since rolling bearings are usually used at a temperature of about 100 ° C, the tempering temperature must be at least 180 ° C.

 Hereinafter, the reasons for limiting the chemical components of the rolling bearing component for high temperature of the present invention will be described.

 (1) Content of C (0.6% or more and 1.3% or less)

 C is an essential element for ensuring strength as a rolling bearing, and must be contained at least 0.6% in order to maintain the hardness after a given heat treatment. Limited to 6%. Also, in the present invention, carbides play an important role in rolling fatigue life as described later, but if the C content exceeds 1.3%, large carbides are generated, Since it was found that the fatigue life was reduced, the upper limit of the C content was limited to 1.3%.

 (2) Si content (0.3% or more and 3.0% or less)

 Si is desirably added because it has the effect of suppressing softening at high temperatures and improving the heat resistance of rolling bearings. However, the effect cannot be obtained if the Si content is less than 0.3%, so the lower limit of the Si content is limited to 0.3%. Although the heat resistance improves with an increase in the Si content, the effect saturates even if it is contained in a large amount exceeding 3.0%, and decreases in hot workability and machinability. Therefore, the upper limit of the Si content was limited to 3.0%.

 (3) Mn content (0.2% or more and 1.5% or less)

Mn is an element used for deoxidation in the production of steel, and is also an element that improves hardenability.It is necessary to add 0.2% or more to obtain this effect. The lower limit of the Mn content was limited to 0.2%. However, if it is contained in a large amount exceeding 1.5%, machinability is greatly reduced, so the upper limit of the Mn content was limited to 1.5%.

 (4) P content (0.03% or less)

 Since P segregates at the austenite grain boundaries of steel and causes a decrease in toughness and rolling fatigue life, the upper limit of the content is set to 0.03%.

 (5) S content (0.03% or less)

 Since S impairs the hot workability of steel and forms nonmetallic inclusions in the steel to reduce toughness and rolling fatigue life, the upper limit of the S content is set to 0.03%. In addition, S has a harmful surface as described above, but also has the effect of improving the machinability. Therefore, it is desirable to reduce S as much as possible, but if it is contained up to 0.005%, it is allowable. Is done.

 (6) Cr content (0.3% or more and 5.0% or less)

 Cι · is an element that plays an important role in the present invention, and is added to improve hardenability, secure hardness by carbide and improve life. Since the addition of 0.3% or more is necessary in order to obtain a predetermined carbide, the lower limit of the Cr content is limited to 0.3%. However, if it is contained in a large amount exceeding 5.0%, large carbides are formed and the rolling fatigue life is reduced, so the upper limit of the Cr content was limited to 5.0%.

 (7) About the content of A1 (less than 0.050%)

 A1 is used as a deoxidizing agent in the production of steel, but it is desirable to reduce it because hard oxide-based inclusions are formed and the rolling fatigue life is reduced. In addition, when a large amount of A1 was contained in excess of 0.050%, a remarkable decrease in rolling fatigue life was recognized, so the upper limit of the A1 content was limited to 0.050%.

 In order to reduce the 81 content to less than 0.005%, the production cost of steel increases, so the lower limit of the A1 content is preferably limited to 0.005%.

 (8) Content of Ding 1 (0.003% or less), O content (0.001 5% or less), N content (0.001 5% or less)

 T i, O and N form oxides and nitrides in the steel and become the starting point of fatigue fracture as non-metallic inclusions, reducing the rolling fatigue life. T i: 0.003%, 〇: 0. 001 5%, N: 0.01 5% was set as the upper limit of each element.

(9) Ni content (0.1% or more and 3.0% or less) Ni is an element that plays an important role in the present invention, and in particular, suppresses the structural change in the rolling fatigue process when used in a high-temperature environment, and also suppresses the decrease in hardness in the high-temperature region. It has the effect of improving the rolling fatigue life. In addition, Ni improves toughness, improves life under foreign material environments, and is effective in improving corrosion resistance. For this reason, since it is necessary to contain Ni at 0.1% or more, the lower limit of the Ni content is limited to 0.1%. However, if a large amount of Ni is contained in excess of 3.0%, a large amount of residual austenite is generated during the quenching process, and a predetermined hardness cannot be obtained, and the cost of steel material rises. Was limited to 3.0%.

 Next, the tempering hardness and carbide of the rolling bearing component for high temperature of the present invention will be described.

 (10) Temper hardness

 Bearings used in high-temperature areas are generally subjected to tempering at a temperature equal to or higher than the environmental temperature in order to stabilize the dimensions in the operating environment. The inventors of the present invention conducted detailed adjustments on the tempering hardness and rolling fatigue life at a temperature of 200 ° C. As a result, a correlation was found between the tempering hardness and the rolling fatigue life, and the tempering hardness was reduced. It was confirmed that the higher the value, the longer the rolling fatigue life tends to be. In particular, when the tempering hardness is the same, it was found that a bearing whose tempering treatment was performed at a higher temperature has a longer life, and a bearing whose tempering hardness is higher even at a high temperature has a longer life. Was done. Furthermore, it was found that when the hardness after the tempering treatment was less than HRC58, the life tended to be sharply reduced, and the life variability became large. In order to improve the life at high temperatures and reduce the variation, it is necessary to maintain a hardness of HCR 58 or more, and the higher the tempering temperature is, the better.

 (11) Carbide

It has been found that the carbides maintain the hardness during tempering, suppress the microstructural changes during rolling fatigue, and have an effect on improving the rolling fatigue life. At this time, the maximum dimensions of carbide and the rolling fatigue life at a depth of 0.1 mm from the bearing surface were investigated, and as a result, the life tended to decrease when large carbides were present. It has been clarified that if large carbides larger than m remain, the life is suddenly shortened, so the maximum size of carbides is specified at 8 m. In the above-mentioned high-temperature rolling bearing component, preferably, the steel material is 0.05% or more and 0.25% by mass. /. It further contains at least one of Mo less than and less than 0.05% and less than 1.0% of V.

 As a result, the rolling fatigue life can be further improved in a foreign substance mixed environment and a high temperature environment, and the hardness after tempering can be improved. Hereinafter, the reasons for limiting the chemical components will be described.

 (1 2) Mo content (0.05% or more and less than 0.25%)

 Mo has the effect of improving the hardenability of steel and preventing softening during tempering by forming a solid solution in the carbide. In particular, Mo is added because it has been found to have an effect of improving the rolling fatigue life at high temperatures. However, when Mo is contained in a large amount of 0.25% or more, the cost of steel material increases, and the machinability deteriorates significantly without reducing hardness during softening treatment to facilitate cutting. The Mo content was limited to less than 0.25%. If the content of Mo is less than 0.05%, there is no effect on carbide formation, so the lower limit of the Mo content was limited to 0.05%.

 (1 3) About V content (0.05% or more and 1.0% or less)

 V combines with carbon to precipitate fine carbides, promotes the refinement of crystal grains, and has the effect of improving strength and toughness.The addition of V improves the heat resistance of steel materials, It suppresses softening, improves rolling fatigue life, and reduces life variability. Since the V content at which this effect is obtained is 0.05% or more, the lower limit of the V content is limited to 0.05%. However, if a large amount of V is contained in excess of 1.0%, machinability and hot workability are reduced, so the upper limit of the V content is limited to 1.0%. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, examples of the present invention will be described.

The steel material having the chemical composition shown in Table 1 was melted by a vacuum induction furnace, forged into a steel ingot having a weight of 150 kg, and then heated and maintained at a temperature of 1200 ° C for 3 hours for hot forging. Was carried out to produce a round bar having a diameter of 50 mm. After normalizing the round bar material at 850 ° C for 1 hour as a normalizing process, it is air-cooled to further facilitate cutting. 790 as softening treatment. After holding at C for 6 hours, the material was cooled down to 650 ° C at a cooling rate of 10 ° C / hour and softened to cool to room temperature in the air.

table 1

 Chemical composition (% by mass)

 No. c Si Mn p s Ni Cr Mo V AI Ti 0 N

A 1 0.81 2.01 0.50 0.018 0.020 0.53 1.49 0.021 0.0023 0.0010 0.009

B 2 1.01 0.75 0.45 0.019 0.020 1.01 1.51 0.020 0.0023 0.0011 0.011 c 3 0.80 2.51 0.44 0.017 0.022 0.55 1.48 0.022 0.0024 0.0013 0.010

D 4 1.21 1.01 0.35 0.018 0.019 0.78 1.49 0.020 0.0025 0.0010 0.011 book E 5 1.05 1.51 0.40 0.019 0.017 2.01 1.50 0.021 0.0022 0.0009 0.008 departure F 6 1.01 1.49 0.45 0.016 0.021 1.51 1.51 0.021 0.0023 0.0010 0.009 light G 7 1.20 1.01 0.25 0.018 0.020 0.79 1.50 0.24 0.021 0.0024 0.0011 0.011 Example H 8 1.01 0.51 0.45 0.019 0.021 2.51 1.51 0.41 0.022 0.0025 0.0010 0.010

1 9 1.00 0.52 0.46 0.020 0.020 1.51 1.52 0.85 0.021 0.0022 0.0009 0.011

J 10 1.00 1.48 1.10 0.018 0.020 1.52 1.48 0.022 0.0023 0.0011 0.009

K 11 1.21 1.00 0.45 0.019 0.019 2.51 2.51 1-1 0.020 0.0023 0.0012 0.010

CD 12 1.01 0.50 0.35 0.017 0.021 0.79 4.51 ― 0.021 0.0025 0.0011 0.010

 M 13 1.01 0.25 0.50 0.020 0.020 0.02 1.50 1-10.020 0.0022 0.0009 0.009

N 14 1.22 0.22 0.45 0.019 0.019 0.02 1.49 ― 1 0.021 0.0023 0.0010 0.010

0 15 1.00 1.51 0.45 0.018 0.019 0.03 1.48 ― ― 0.021 0.0024 0.0011 0.011

P 16 1.23 1.01 0.35 0.017 0.018 0.02 1.51 0.020 0.0023 0.0011 0.010

Q 17 0.55 1.00 0.40 0.016 0.017 0.50 1.50 0.25 0.020 0.0022 0.0010 0.010

R 18 1.55 1.01 0.35 0.017 0.018 1.00 1.50 0.40 0.022 0.0023 0.0011 0.009

S 19 1.21 1.00 0.30 0.065 0.040 0.50 1.50 0.065 0.0522 0.0025 0.025

T 20 1.20 1.01 2.65 0.018 0.020 1.50 1.45 0.021 0.0021 0.0010 0.011

U 21 1.21 0.98 0.45 0.017 0.019 1.50 6.01 0.020 0.0021 0.0011 0.009

V 22 1.10 0.55 0.15 0.017 0.020 1.00 0.22 0.01 0.02 0.003 0.0020 0.0010 0.009

W 23 1.15 1.01 0.45 0.018 0.020 1.50 1.45 0.35 0.021 0.0022 0.0011 0.010

X 24 1.15 1.00 0.40 0.019 0.021 2.00 1.40 2.01 0.022 0.0021 0.0010 0.010

Y 25 1.21 4.01 0.55 0.019 0.019 1.00 1.40 0.020 0.0022 0.0010 0.009 z 26 1.20 0.55 0.45 0.018 0.018 4.23 1.35 0.019 0.0020 0.0009 0.010

<Hardness investigation>

 To measure the hardness after quenching and the hardness after carbonitriding, a cylindrical test piece with a diameter of 20 mm and a length of 100 mm was prepared by machining from a material with a diameter of 5 O mm. did.

 The quenching process is performed by heating in a salt furnace, soaking at 850 ° C for 30 minutes,

This was performed by quenching in oil at 80 ° C. Thereafter, as a tempering treatment, heating was similarly performed in a sonolet furnace, and a tempering treatment was carried out at 350 ° C. for 2 hours, followed by air cooling.

The carbonitriding process using a gas atmosphere furnace used in ordinary production processes, 1 carbon potential in RX gas atmosphere. 0 to 1.2%, the amount of NH _3. 5 to a 1 0% 8 After being kept at 50 ° C for 60 minutes, it was quenched in oil. Thereafter, tempering was performed at 350 ° C. for 120 minutes.

 A 10 mm-thick disk-shaped test piece was cut from the center of the quenched and tempered test piece or the test piece that was tempered after carbonitriding, and both sides were polished by wet polishing. A test piece for hardness measurement was prepared.

 The hardness was measured at a position 2 mm deep from the surface in the cross section of the test piece using a mouth-well hardness tester, and the average value at seven points was determined as the tempered hardness.

 Rolling fatigue life test>

 In order to confirm the performance as a bearing component, a fatigue test was performed using a thrust-type rolling fatigue life tester, and the life of each material was evaluated.

 The test piece used for the life evaluation was a ring-shaped thrust-type rolling fatigue life test piece with an outer diameter of 47 mm, an inner diameter of 29 mm, and a thickness of 7 mm, which was machined from a 50 mm diameter round bar material. Roughed.

 As the heat treatment of the roughened test pieces, quenching and tempering and carbonitriding were performed. The processing used the actual furnace used in the normal production process.

For quenching and tempering, 30 minutes at 850 ° C using a gas atmosphere furnace while controlling the carbon potential in the RX gas atmosphere based on the carbon content of each steel to prevent decarburization and carburization. After holding, it was quenched in oil. Thereafter, tempering was performed at 350 ° C. for 120 minutes. In the carbonitriding treatment, a heat treatment was performed under the same conditions as those of the hardness test piece.

 After the completion of the heat treatment, both surfaces of the test piece were polished to a mirror finish. For the carbonitrided test specimen, the machining allowance for polishing was set to 0.1 mm on both sides. The rolling fatigue life test was performed using a thrust rolling fatigue life tester. Table 2 shows the conditions of the test. The test was performed under normal temperature environment and at 200 ° C environment, and was also performed under an environment in which the environment in which foreign substances were mixed was reproduced. Table 2

Rolling contact fatigue life test conditions

疲労試験は、 同一条件で 1 5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 1 0 %となる寿命を各材料の寿命として判定した。 なお、 表 2に おける比較例 N o . 1 3は汎用の S U J 2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。

The fatigue test was repeated 15 times under the same conditions, and the life when the cumulative damage probability in the Weibull probability was 10% was determined as the life of each material. The comparative example No. 13 in Table 2 is a general-purpose SUJ2, and the life value of each material is described as a ratio when the life of the quenched and tempered material is set to 1.0.

 <Carbide>

Thrust-type rolling fatigue life specimens were used to measure the carbides present in the steel. A cross section of the ring was cut from a test piece processed into a thrust rolling fatigue life test piece by performing various heat treatments, and a micro test piece for structure observation was manufactured. The specimen was mirror-finished and corroded by Picral etchant to observe carbides. In this micro sample, carbide at a depth of 0.1 mm from the surface layer of the rolling contact surface was observed with an optical microscope, and the largest carbide in a visual field area of 50 mm ² was measured.

Table 3 shows the results of the above-mentioned tempering hardness at 350 ° C, rolling fatigue life at room temperature and 200 ° C, rolling fatigue life under foreign matter-contaminated conditions, and the maximum carbide size. Table 4 shows comparative examples. Table 3

 350 ° C temper hardness Maximum carbide size Room temperature! Dynamic fatigue life 200 ° C rolling fatigue Foreign matter rolling life

No Ratio of steel life

 (HRC) Life ratio Life ratio rn z: Dish day 200 ° C

HT 58.8 2.5 3.2 4.0 3.6 4.3

1 A

 Carbonitriding 59.3 3.3 3.5 4.8 4.1 5.5

HT 59.4 3.5 4.5 6.9 4.8 7.3

2 B

 Carbonitriding 59.8 3.7 4.7 7.8 5.2 8.4

HT 58.8 2.5 3.1 5.1 3.4 5.3

3 C

 Carbonitriding 60.0 2.9 3.5 5.8 4.0 6.3

HT 60.5 2.6 10.1 14.0 10.4 14.2

4D

 Carbonitriding 61.1 3.1 10.7 15.2 11.3 15.7

HT 59.9 3.3 5.1 8.1 5.4 8.3

5 E

 Carbonitriding 59.3 3.9 7.0 10.2 7.7 10.8

HT 60.0 3.2 6.1 9.5 6.3 9.8

6 F book

 Carbonitriding 60.7 4.0 8.5 11.1 8.9 11.6 t HT light 60.7 3.5 7.3 11.1 7.7 11.4

/

 Carbonitriding Example 61.5 4.7 7.9 13.2 8.5 13.8

HT 59.8 2.7 4.0 7.6 4.3 7.9

8 H

 Carbonitriding 59.0 3.5 7.0 9.5 7.5 10.0

HT 59.5 3.2 4.5 8.7 4.9 9.1

9 I

 Carbonitriding 60.1 4.0 6.5 10.0 7.1 10.5

HT 59.6 4.2 5.2 9.1 5.4 9.3

10 J

 Carbonitriding 59.9 5.0 7.3 9.4 7.8 10.0

HT 60.5 6.1 9.4 13.5 9.7 13.8

11K

 Carbonitriding 60.0 6.7 7.5 10.3 8.0 10.8

HT 59.8 6.8 6.4 9.6 6.7 9.8

12

Carbonitriding 61.1 7.5 4.2 6.5 4.7 7.0

Table 4

 0 ° C temper hardness Maximum ash size Life ratio

No. Steel 35 Room temperature rolling fatigue life 200 ° C rolling fatigue Foreign matter rolling life

 Processing

 (HRC) m) Life ratio Life ratio rh / dish 200 ° C

HT 55.6

 13 1.1 1.0 1.0 1.0 1.0

M

 Carbonitriding 57.2 2.8 1.8 1.4 2.0 1.7

HT 56.0 2.5 1.1 1.3 1.1 1.2

14 N

 Carbonitriding 57.3 4.2 1.9 1.7 2.2 1.9

HT 60.1 2.8 2.1 2.5 2.0 2.5

15 0

 Carbonitriding 60.3 4.3 2.2 2.8 2.6 3.1

HT 60.1 3.0 2.2 2.1 2.0 1.9

16 p

 Carbonitriding 60.8 4.2 3.0 2.8 3.3 3.2

HT 53.0 2.5 0.4 0.7 0.3 0.6

17 Q

 Carbonitriding 54.3 2.3 0.5 1.1 0.9 1.4

HT 54.2 6.5 1.6 1.4 1.9 1.5

18 R

 Nitriding 61.5 9.2 0.9 1.0 1.0 1.2

HT 59.4 4.4 1.4 2.0 1.4 1.7

19 S ratio

 Nitriding 60.3 5.1 2.4 2.4 2.5 2.6

HT 59.4 7.7 1.9 1.5 1.9 1.3

20 T example

 ; Nitriding 59.9 6.5 1.7 1.7 1.9 1.8

HT 62.5 17.0 1.4 1.1 1.2 0.9

21 U k ± j

 ; Ashification 63.0 29.0 0.8 0.8 0.9 1.1

HT 56.5 3.8 0.7 0.3 0.4 0.6

22 V

 Carbonitriding 57.7 3.7 0.8 0.6 0.9 0.5

HT 59.4 3.0 1.3 1.5 1.1 1.3

23 W

 Carbonitriding 60.0 3.4 2.2 2.2 2.3 2.3

HT 61.5 2.4 2.0 2.5 1.9 2.1

24 X

 Carbonitriding 62.0 3.3 2.2 2.7 2.3 2.9

HT 62.5 1.4 2.3 2.7 2.3 2.9

25 Y

 Carbonitriding 62.6 2.7 2.3 2.9 2.7 3.0

HT 62.4 1.5 2.4 2.6 2.3 2.8

26 Z

Carbonitriding 62.3 2.5 2.1 2.9 2.6 2.9

From the results of Tables 3 and 4, it was found that in the present invention example having the composition range of the present invention, the hardness was HRC 58 or more even after tempering at 350 ° C. Further, in the present invention example, even when a simple quenching and tempering treatment (HT) is performed, the rolling fatigue life at room temperature and 200 ° C. and the rolling fatigue life under the foreign matter condition are larger than those of the comparative example. It turned out to be high. It was also found that excellent rolling contact fatigue life could be obtained when carbonitriding was performed instead of quenching. Further, in the example of the present invention, it was found that the maximum dimension of the carbide at a depth of 0.1 mm from the surface layer of the rolling contact surface was 8.0 μm or less.

 The embodiments disclosed this time should be considered in all respects as illustrative and not restrictive. 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.

 As described above, the present inventors have found out the optimum compositional elements and their contents. By performing quenching and tempering, excellent rolling can be achieved under foreign matter-mixed conditions without carbonitriding. In addition to providing fatigue life, even if tempering at high temperatures (for example, 350 ° C), inexpensive high-temperature rolling bearing parts with high resilience and hardness could be obtained. Industrial applicability

 INDUSTRIAL APPLICABILITY The present invention can be advantageously applied to a high-temperature rolling bearing component used in a foreign substance-mixed environment and a high-temperature environment.

Claims

The scope of the claims 1. A high-temperature rolling bearing component having an inner ring, an outer ring, and a rolling element,  Content of alloying elements is% by mass, C is 0.6% or more and 1.3% or less, 31 is 0.3% or more and 3.0% or less, Mn is 0.2% or more and 1.5% or less , P 0.03% or less, S 0.03% or less, J]: 0.3% or more 5.0% or less, 1 0.1% or more 3.0% or less, 1 0.005% % Or less, 0.001% or less for Ding 1, 0.005% or less for O, 0.015% or less for N, and the balance is made of steel consisting of Fe and unavoidable impurities, and after quenching or carburizing A high-temperature rolling bearing having a configuration tempered after nitriding, having a hardness after tempering of HRC 58 or more, and a maximum carbide size of 8 μm or less. parts. 2. The steel material is 0.05% by mass. /. 2. The high-temperature rolling bearing component according to claim 1, further comprising at least one of Mo of at least 0.25% and V of at least 0.5% and at most 1.0%. O 00/28102 Claim of amendment PCT / JP99 / 06253 [March 28, 2000 (28.03.00) Accepted by the International Bureau: Claim 1 originally filed was amended; other claims unchanged. (1 page)]  1. (After amendment) High-temperature rolling bearing parts having an inner ring, outer ring and rolling elements,  Content of alloying elements is% by mass, C is 0.6% or more and 1.3% or less, ≤ 1 is 0.5% 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, 〇1 to 0.3% or more, 5.0% or less, Ni is 0.1% or more, 3.0% or less, A1 is 0 050% or less, T i is 0.003% or less, O is 0.001 5% or less, 0.015% or less of N, each containing at least each element, the balance being made of a steel material composed of Fe, and having a structure tempered after quenching or carbonitriding, and A high-temperature rolling bearing component having a hardness after tempering of HRC 58 or more and a maximum carbide size of 8 μm or less.  2. The steel material is characterized in that the steel material further contains at least one of Mo of 0.05% or more and less than 0.25% and V of 0.05% or more and 1.0% or less in mass%. The high-temperature rolling bearing component according to claim 1. 1 6 Amended paper (Article 19 of the Convention)