EP1420078A2 - Lagerstahl mit guter Korrosionsbeständigkeit - Google Patents

Lagerstahl mit guter Korrosionsbeständigkeit Download PDF

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Publication number
EP1420078A2
EP1420078A2 EP03026063A EP03026063A EP1420078A2 EP 1420078 A2 EP1420078 A2 EP 1420078A2 EP 03026063 A EP03026063 A EP 03026063A EP 03026063 A EP03026063 A EP 03026063A EP 1420078 A2 EP1420078 A2 EP 1420078A2
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Prior art keywords
bearing steel
steel
less
carbide
concentration
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EP03026063A
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English (en)
French (fr)
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EP1420078A3 (de
EP1420078B1 (de
Inventor
Kinami Koyo Seiko Co. Ldt. Toshiva
Kimura Daido Tokushuko K.K. Toshimitsu
Nishisaka Koyo Seiko Co. Ldt. Hisato
Goto Koyo Seiko Co. Ldt. Masao
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JTEKT Corp
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Koyo Seiko Co Ltd
JTEKT Corp
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Publication of EP1420078A3 publication Critical patent/EP1420078A3/de
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/28—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in one step
    • C23C8/30—Carbo-nitriding
    • C23C8/32—Carbo-nitriding of ferrous surfaces

Definitions

  • the present invention relates to bearing steel and particularly to bearing steel which is excellent in corrosion resistance, surface fatigue strength and rolling fatigue life and which is adapted for large-size bearing parts in a rolling machine (mill), a thermal power generator, a hydraulic powder generator, etc.
  • a carburized material of case-hardened steel such as JIS SCr, JIS SCM or JIS SNCM has been heretofore used as bearing steel for large-size bearing parts.
  • JIS SCr case-hardened steel
  • JIS SCM JIS SCM
  • JIS SNCM JIS SNCM
  • Japanese Patent Publication 14416/1990 has disclosed bearing steel adapted for large-size bearing parts and containing JIS SNCM 815 as a base material, and an appropriate amount of Si and Ni added to the base material.
  • rust may be formed due to penetration of rolling water in accordance with the rolling machine.
  • the rust brings about reduction in rolling fatigue life. Therefore, development of bearing steel more excellent in corrosion resistance is required newly so that the bearing steel can be adapted for large-size bearing parts.
  • carbonitriding treatment is more effective than ordinary carburizing treatment because nitriding improves heat resistance and because stability of residual austenite improves rolling fatigue strength against contaminants (rolling fatigue strength under an environment contaminated with dust). Accordingly, development of bearing steel excellent in carbonitriding characteristic is also required.
  • the invention is developed to solve the problem and an object of the invention is to provide bearing steel which is excellent in corrosion resistance, surface fatigue strength and rolling fatigue life and excellent in carbonitriding characteristic and which is particularly adapted for large-size bearing parts.
  • the invention is characterized by having the following arrangement.
  • FIG. 1 is a view typically showing rod-like carbide existing in steel.
  • the inventors have examined various alloy elements. As a result, it has been found that both reduction in the amount of added Si and addition of an appropriate amount of Ni and Cr are effective in improving corrosion resistance.
  • the reason why the presence of rod-like carbide deteriorates both rolling fatigue life and impact resistance can be conceived as follows. That is, the bearing steel cracks along a surface of rod-like carbide which is an inclusion, or the rod-like carbide is apt to operate as a start point of the crack. It is further conceived that corrosion resistance also deteriorates because the bearing steel is apt to corrode along the surface of the rod-like carbide. In the invention, it has been found that those properties deteriorate particularly when rod-like carbide having an aspect ratio of not lower than 3 and having a minor diameter of not larger than 2 ⁇ m is produced.
  • the inventors have also found that carbonitriding treatment improves both corrosion resistance and rolling fatigue life and that addition of an appropriate amount of Ni and Mo is effective in improving rolling fatigue life.
  • the invention is based on the aforementioned knowledge.
  • the size of each oxide inclusion in the steel before carburizing or carbonitriding treatment is preferably selected to be not larger than 50 ⁇ m in terms of the maximum diameter. That is, the inventors have found that corrosion resistance can be improved when the size of each oxide inclusion in the steel is reduced to be not larger than 50 ⁇ m.
  • the steel is preferably subjected to intermediate annealing and secondary quenching/tempering successively so that the steel exhibits a surface C concentration of not lower than 0.7 %, contains carbide having an area percentage of not higher than 15 % and contains 0.1 % by area or less of carbide having an aspect ratio of not lower than 3 and having a minor diameter of not smaller than 2 ⁇ m.
  • the steel may further contain 0.05 wt% to 1. 0 wt% of V, and 0.1 wt% or less of Nb as alloy components.
  • crystal grains can be made so fine that characteristic of the bearing steel can be improved.
  • C 0.10 % to 0.35 %
  • the amount of C needs to be not smaller than 0.10 % in order to obtain required strength as bearing steel and keep sufficient surface hardness after carburizing or carbonitriding treatment. If the content of C is larger than 0.35 %, both toughness and machinability are reduced. Accordingly, the content of C is selected to be in a range of from 0.10 % to 0.35 %.
  • Si ⁇ 0.5 % Si is effective in making a quench-hardened martensitic structure dense to thereby improve toughness and fatigue resistance of steel. In this sense, Si is a significant component in the invention.
  • Mn 0.2 % to 1.5 %
  • Mn is an element which operates as a deacidifying and desulfurizing element at the time of melting steel and which is effective in improving hardenability of steel. In this invention, therefore, the steel contains 0.2 % or more of Mn. Both processability and machinability, however, deteriorate if the content of Mn is larger than 1.5 %. Accordingly, the upper limit of the content of Mn is set at 1.5 %.
  • Ni 1.0 % to 3.5 %
  • Ni is a significant component in the invention and has a great effect on improvement in corrosion resistance of steel.
  • Ni is an element effective in improving hardenability of steel and toughness of steel after quenching/tempering.
  • the steel contains 1.0 % or more of Ni. Both toughness and processability of steel, however, deteriorate if the content of Ni is larger than 3.5 %. Accordingly, the upper limit of the content of Ni is set at 3.5 %.
  • the content of Ni is set from 2.0 to 3.0%.
  • Cr: 1.0 % to 5.0 % Cr is also a significant component in the invention and has a great effect on improvement in corrosion resistance of steel. Cr is an element effective in improving hardenability of steel and strength and toughness of steel after quenching/tempering. In the invention, therefore, the steel contains 1.0 % or more of Cr. If the content of Cr is larger than 5.0 %, both hardenability and machinability, however, deteriorate while the effect on improvement in corrosion resistance is saturated. Accordingly, the upper limit of the content of Cr is set at 5.0 %. Preferably, the content of Cr is set from 1.0 to 2.0 %.
  • Mo 0.03 % to 2.5 % Mo is an element effective in improving strength of steel.
  • the steel contains 0.03 % or more of Mo. Both hardenability and machinability, however, deteriorate simultaneously if the content of Mo is larger than 2.5 %. Accordingly, the upper limit of the content of Mo is set at 2.5 %.
  • the contents of Mo is set from 0.3 to 1.0 %.
  • Al: 0.005 % to 0.050 % Al forms AlN effective in making crystal grains fine. In the invention, therefore, the steel contains 0.005 % or more of Al. The effect on prevention of production of coarse crystal grains is however reduced as well as cleanliness of steel deteriorates if the content of Al is larger than 0.050 %.
  • the upper limit of the content of Al is set at 0.050 %.
  • Ti ⁇ 0.003 % Ti generates a hard precipitate TiN which operates as a fracture start point of rolling fatigue fracture and which causes reduction in rolling fatigue life. In the invention, therefore, the content of Ti is limited to be not larger than 0.003 %.
  • O ⁇ 0.0015 % O reduces cleanliness of steel to cause reduction in rolling fatigue life. In the invention, therefore, the content of O is limited to be not larger than 0.0015 %.
  • N ⁇ 0.025 % N is bonded to Al to generate AlN which operates to make crystal grains fine. Strength of steel, however, deteriorates if a large amount of N is contained.
  • the upper limit of the content of N is set at 0.025 %. More preferably, the content of N is in a range of from 0.01 % to 0.02 %.
  • V 0.05 % to 1.0 % Nb: ⁇ 0.1 %
  • Each of V and Nb is an element that contributes to making crystal grains fine. The effect on making crystal grains fine is reduced if the content of each of V and Nb is too large. Accordingly, when each of V and Nb needs to be added as a selected element, the steel contains 0.05 % to 1.0 % of V, and 0.1 % or less of Nb.
  • Surface C Concentration Surface C concentration after heat treatment is important in order to keep strength of steel.
  • a surface C concentration of not lower than 0.7 % is required for obtaining required hardness and rolling fatigue life.
  • surface C concentration is preferably set from 0.7 % to 0.9 %.
  • Carbide Fine carbide is required for ensuring rolling fatigue life. If the area percentage of carbide is higher than 15 %, strength of steel is reduced in reverse.
  • rod-like carbide 10 having an aspect ratio of not lower than 3 in terms of the ratio of major diameter to minor diameter and having a minor diameter of not smaller than 2 ⁇ m is produced as shown in Fig. 1. If the area percentage of the rod-like carbide 10 produced thus is higher than 0.1 %, both rolling fatigue life and impact resistance are reduced remarkably.
  • Oxide Inclusion The presence of an oxide inclusion reduces rolling fatigue life because the oxide inclusion serves as a start point of rolling fatigue fracture. In addition, the presence of such an oxide inclusion large in size reduces corrosion resistance because the interface between the oxide inclusion and a matrix is preferentially corroded under a corrosive environment.
  • the maximum diameter of the oxide inclusion is preferably controlled to be not larger than 50 ⁇ m in order to obtain bearing steel excellent in corrosion resistance and rolling fatigue life.
  • Heat Treatment When the amount of added alloy elements is large after carburizing or carbonitriding, there is the possibility that required surface hardness cannot be obtained because the martensitic transformation point (Ms point) of steel becomes so low that a large amount of residual austenite is produced. It is therefore preferable that secondary quenching/tempering is performed. In this case, intermediate annealing may be preferably performed before the second quenching so that the formof carbide is made appropriate to improve hardenability of the matrix. Further, addition of nitrogen is effective in improving corrosion resistance.
  • a vacuum induction melting furnace 150 g of steel having chemical components shown in Table 1 was melted and hot-forged at 1200°C to produce a round bar having a diameter of 32 mm or 65 mm. After the round bar was normalized at 900°C, the round bar was subjected to spheroidizing treatment as softening treatment at 760°C to prepare a test material. For evaluation of cleanliness of the material, a size distribution of oxide inclusion particles was measured by an acid dissolution extraction-pore electrical resistance method (method for measuring volume of particles on the basis of change in electrical resistance at the time of passage of the particles through pores).
  • a round bar of ⁇ 20 mm was cut out of an R/2 portion of the material. After the round bar was quenched from 850°C, about 30 g of a 1 mm-thick thin plate was cut out of the round bar and subjected to acid dissolution. Extraction of oxide inclusions by acid dissolution was performed with a solution of sulfuric acid and permanganic acid. The extracted oxide inclusions were dispersed into 200 cc of an electrolytic solution. A size distribution of particles in 500 ⁇ l of the dispersed solution was measured in the condition of an aperture size (pore size) of 100 ⁇ m by the Multisizer made by Beckman Coulter, Inc.
  • Table 1 shows the measured maximum diameter of the oxide inclusions. In any test material of steel according to the invention, the maximum diameter of the oxide inclusions was not larger than 50 ⁇ m.
  • a corrosion test was performed in a humid condition and in a crevice corrosion condition. Specifically, a roughly processed test specimen having a diameter of 20 mm and a length of 36 mm was cut out of each of the materials. The test specimen was carburized at 960°C for 22 hours in a furnace in an atmosphere of 1. 2 % carbonpotential as a carburizing condition. After quenched from 860°C, the test specimen was intermediately annealed at 660°C for 4 hours, secondarily quenched at 790°C and tempered at 180°C. After a cylindrical surface of the test specimen was then ground-finished, the test specimen was subjected to the corrosion test.
  • the roughly processed test specimen provided in the aforementioned manner was carburized in the same condition as described above and then carbonitrided at 850°C for 7 hours in a furnace in an atmosphere of 1.2 % carbon potential and 5 % ammonia addition as a carbonitriding condition.
  • the test specimen was intermediately annealed and secondarily quenched in the same manner as described above.
  • a combined cycle testing machine was used in the corrosion test. The state of corrosion was examined after each test specimen was left at a test temperature of 49°C ⁇ 1°C with 95 % or higher relative humidity for 24 hours. With respect to crevice corrosion, the test specimen was placed quietly on a V block so that a contact portion between the V block and the test specimen was in the crevice corrosion condition.
  • a center portion of the test specimen was cut with a micro-cutter and ground-finished. Then, a C concentration distribution from a surface layer of the test specimen was measured by an electron probe microanalyser (EPMA) to thereby obtain the surface C concentration.
  • EPMA electron probe microanalysis
  • Carbide was measured as follows. A center portion of the test specimen was cut with amicro-cutter and ground-finished. Then, the test specimen was corroded by picral so that carbide came out from the test specimen. The carbide was observed in five visual fields by a 5000-power scanning electron microscope (SEM), so that the area percentage of carbide and the major and minor diameters of all carbide particles as shown in Fig. 1 were measured by image analysis.
  • SEM 5000-power scanning electron microscope
  • a thrust type rolling fatigue test was performed in order to examine rolling fatigue strength of bearing parts.
  • a ring-like test specimen having an outer diameter of 63 mm, an inner diameter of 28.7 mm and a thickness of 9 mm was cut out of each material so that it was used as a roughly processed test specimen.
  • test specimen was subjected to carburizing treatment and quenching/tempering treatment as heat treatment.
  • the carburizing condition was the same as in the corrosion test specimen.
  • one test surface of the test specimen was ground-finished by 0.15 mm and the other test surface of the test specimen was lapped so that the test specimen was used as a thrust type rolling fatigue test specimen.
  • the roughly processed test specimen provided in the aforementioned manner was subjected to carbonitriding treatment and quenching/tempering treatment.
  • the carbonitriding condition was the same as in the corrosion test specimen.
  • the test specimen was subjected to the same ground finish so that the test specimen was used as a thrust type rolling fatigue test specimen.
  • a thrust type rolling fatigue testing machine was used in the test.
  • the test was performed in the test condition shown in Table 2.
  • High-speed steel gas atomized powder having a hardness of 750 Hv and having a particle size of 100 ⁇ m to 180 ⁇ m obtained by classification was used in the test under a contamination environment.
  • the rolling fatigue life was evaluated on the basis of the number (L 10 ) of cycles in which the probability of accumulated breakage reached 10 % in a Weibull distribution and the number (L 50 ) of cycles in which the probability of accumulated breakage reached 50 % in a Weibull distribution when the test was repeated by 16 cycles in the same test condition.
  • a Charpy impact test was performed in order to examine toughness of bearing parts.
  • a roughly processed test specimen which was 12 mm wide, 14 mm high and 55 mm long and in which a notch having a depth of 1.8 mm and a curvature radius of 10 mm was formed in the lengthwise center of the test specimen was cut out of each of the materials.
  • the test specimen was subjected to carburizing and quenching/tempering treatment as heat treatment.
  • the carburizing condition was as follows.
  • the test specimen was carburized at 930°C for 4 hours in a furnace in an atmosphere of 1.2 % carbon potential. After quenched from 850°C, the test specimen was intermediately annealed at 660°C for 4 hours, secondarily quenched from 790°C and tempered at 180°C. After the heat treatment, the test specimen was ground into a test specimen which was 10 mm wide and 10 mm high and in which a notch having a depth of 2 mm and a curvature radius of 10 mm was formed in the test specimen. The test specimen was subjected to the Charpy test.
  • the roughly processed test specimen provided in the aforementioned manner was carbonitrided and quenched/tempered.
  • the carbonitriding condition was as follows. After carburized in the same manner as described above, the test specimen was carbonitrided at 850°C for 5 hours in a furnace in an atmosphere of 1.2 % carbon potential and 5% ammonia addition. Then, the test specimen was intermediately annealed and secondarily quenched/tempered in the same manner as described above. After the heat treatment, the test specimen was ground-finished in the same manner as described above. The test specimen was subjected to the Charpy test. A Charpy testing machine was used in the test. Energy absorbed at breakage of the test specimen was measured at ordinary temperature.
  • Table 3 shows test results of the carburized materials.
  • the surface C concentration was not lower than 0.7 %
  • the area percentage of carbide was not higher than 15 %
  • the area percentage of rod-like carbide was not higher than 0.1 %.
  • the term "rod-like carbide” used herein means carbide having a maj or diameter/minor diameter ratio (aspect ratio) of not lower than 3 and having a minor diameter of not smaller than 2 ⁇ m.
  • the Charpy impact value of steel according to the invention is equal to or greater than that of steel according to Comparative Examples. It is obvious that the steel according to the invention is excellent in crushing strength as bearing parts.
  • Table 4 shows test results of the carbonitrided materials.
  • the surface C concentration was not lower than 0.7 %
  • the area percentage of carbide was not higher than 15 %
  • the area percentage of rod-like carbide was not higher than 0.1 %. Accordingly, it is obvious that steel according to the invention is more excellent in corrosion resistance, rolling fatigue life and impact value than steel according to Comparative Examples. It is further obvious that the carbonitrided materials are more excellent in corrosion resistance than the carburized materials, and that the rolling fatigue life of steel made of any one of the carbonitrided materials is improved under the contamination condition.
  • bearing steel which exhibits excellent corrosion resistance even in the case where the bearing steel is adapted to bearing parts in a rolling machine, a thermal power generator, a hydraulic power generator, etc. and which is excellent in surface fatigue strength and rolling fatigue life and also excellent in carbonitriding characteristic.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Rolling Contact Bearings (AREA)
EP03026063.2A 2002-11-12 2003-11-12 Lagerstahl mit guter Korrosionsbeständigkeit Expired - Lifetime EP1420078B1 (de)

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Application Number Priority Date Filing Date Title
JP2002328854 2002-11-12
JP2002328854 2002-11-12

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EP1420078A2 true EP1420078A2 (de) 2004-05-19
EP1420078A3 EP1420078A3 (de) 2006-05-03
EP1420078B1 EP1420078B1 (de) 2019-02-27

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1978124A1 (de) * 2007-04-05 2008-10-08 Kabushiki Kaisha Kobe Seiko Sho Schmiedestahl, Schmiedestück und Kurbelwelle
EP2169082A1 (de) * 2008-09-30 2010-03-31 Kabushiki Kaisha Kobe Seiko Sho Schmiedestück aus Stahl 0.15-0.75%C, Si, Mn,Ni,Cr,Mo,V und Al und Kurbelwelle
WO2016107517A1 (zh) * 2014-12-30 2016-07-07 中车戚墅堰机车车辆工艺研究所有限公司 一种铁路辙叉用高耐磨合金钢及其制造方法
CN106893947A (zh) * 2017-03-28 2017-06-27 北京科技大学 一种可耐400度高温的轴承钢的制备方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2386669B1 (de) 2008-12-12 2019-03-27 JTEKT Corporation Bestandteil eines lagers, herstellungsverfahren dafür und wälzlager mit dem bestandteil
JP7152832B2 (ja) 2018-06-18 2022-10-13 株式会社小松製作所 機械部品
JP7270343B2 (ja) 2018-06-18 2023-05-10 株式会社小松製作所 機械部品の製造方法
CN114032470B (zh) * 2022-01-07 2022-04-05 北京科技大学 一种渗碳轴承钢及其制备方法

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US4026727A (en) 1975-11-04 1977-05-31 A. Finkl & Sons Company Fatigue resistant steel, machinery parts and method of manufacture thereof
JPH0214416A (ja) 1988-07-01 1990-01-18 Hitachi Ltd 薄膜磁気ヘッド
US5383768A (en) 1989-02-03 1995-01-24 Hitachi, Ltd. Steam turbine, rotor shaft thereof, and heat resisting steel
JPH03100142A (ja) 1989-09-13 1991-04-25 Kobe Steel Ltd 圧壊特性の優れた軸受用肌焼鋼およびその製造方法
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JPH0860294A (ja) 1994-08-17 1996-03-05 Kobe Steel Ltd 疲労強度に優れた機械構造部品の製造方法および該機械構造部品製造用肌焼鋼
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EP2169082A1 (de) * 2008-09-30 2010-03-31 Kabushiki Kaisha Kobe Seiko Sho Schmiedestück aus Stahl 0.15-0.75%C, Si, Mn,Ni,Cr,Mo,V und Al und Kurbelwelle
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CN106893947B (zh) * 2017-03-28 2018-07-27 北京科技大学 一种可耐400度高温的轴承钢的制备方法

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