EP2872787A1

EP2872787A1 - Rolling bearing element, in particular rolling bearing ring

Info

Publication number: EP2872787A1
Application number: EP13732126.1A
Authority: EP
Inventors: Christian SCHULTE-NÖLLE
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2012-07-16
Filing date: 2013-06-25
Publication date: 2015-05-20
Also published as: KR20150036049A; CN104662312B; DE102012212426B3; WO2014012748A1; CN104662312A; CA2870114A1; US20150184695A1

Abstract

The invention relates to a rolling bearing element (2), in particular a rolling bearing ring (3, 4), said rolling bearing element being made of an austenitic steel which has a composition of 16 - 21 mass percent chromium, 16 - 21 mass percent manganese, 0.5 to 2.0 mass percent molybdenum, a total of 0.8 to 1.1 mass percent carbon and nitrogen, wherein the ratio of carbon to nitrogen is 0.5 to 1.1, up to 2.5 mass percent melting-related impurities, and a remaining mass percent of iron. The sum of all the components equals 100 mass percent, and the rolling bearing element has a surface layer (6) which is produced by means of at least one measure for diffusing carbon and/or nitrogen into regions near the surface of the rolling bearing element and which contains carbon and/or nitrogen.

Description

Name of the invention

Rolling element, in particular rolling bearing ring description

FIELD OF THE INVENTION The invention relates to a rolling bearing element, in particular a rolling bearing ring, which rolling bearing element is formed from an austenitic steel.

Background of the invention

Rolling or rolling bearing elements, in particular rolling bearing rings, rolling elements, rolling elements receiving Wälzkörperkäfige etc., are known to be used in different fields of technology. In this case, corresponding rolling bearing elements are regularly seen to have high mechanical and / or corrosive stresses during operation.

Known antifriction bearing elements are formed, for example, from stainless, martensite rolling bearing steels with carbide phases embedded therein, which, however, do not have sufficient corrosion resistance with respect to corrosive media. Rolling bearing elements of higher-alloyed steels exhibit improved corrosion resistance compared with corrosive media, but these generally have inferior mechanical properties, in particular with regard to wear resistance, which is due to their homogeneous austenitic or so-called duplex steels ferritic-austenitic microstructure. Accordingly, the property profile of known roller bearing elements is often unsatisfactory in view of their mechanical properties, in particular wear resistance, overstress resistance, and their corrosion resistance to corrosive environments.

Summary of the invention

The invention is thus based on the problem of specifying an improved bearing element on the other hand.

To solve this problem, it is provided according to the invention in a roller bearing element of the type mentioned that it contains a nitrogen (N) and / or carbon (C) formed by at least one measure for the diffusion of carbon and / or nitrogen into surface areas of the rolling bearing element Has edge layer.

The formation of a nitrogen and / or carbon-containing surface layer, the rolling bearing element according to the invention, both in terms of its mechanical properties, in particular surface hardness, wear resistance, rollover resistance, etc., as well as its corrosion resistance to corrosive media, that is, especially in chloride-containing media As in seawater or the like, an excellent property profile.

In particular, the rolling bearing element according to the invention is thus also suitable for so-called media lubrication, in which the lubrication of the rolling bearing element according to the invention comprehensive bearing not via lubricants such as greases or lubricating oils, but via the respective system liquid of the site of the bearing. Media-lubricated roller bearings are z. B. used when the rolling bearing sealing gaskets are undesirable and / or due to risk of contamination common lubricant should be dispensed with. So far, in particular, the media lubrication with aqueous solutions was problematic, as with aqueous solutions, especially under highly dynamic conditions, the formation of a sufficiently viable lubricating film between the rolling elements and the rolling bearing rings of the bearing is hardly possible.

Accordingly, the antifriction bearing element according to the invention can be made of an austenitic steel having a composition of 16-21% by mass of chromium, 16-21% by mass of manganese, 0.5% to 2.0% by mass of molybdenum, in total 0.8-1.1% by mass of carbon and nitrogen, wherein the ratio of carbon to nitrogen is 0.5 to 1.1, up to 2.5% by weight of impurity caused by impurities and a balance of iron by mass, the sum of all constituents being 100% by mass.

The rolling bearing element according to the invention is formed of a corrosion-resistant austenitic steel from the house. Two possible steel variants are described below. Two examples of concrete compositions of the aforementioned steel are shown in the following table. The data refer in each case to percent by mass.

In addition, each of a residue of iron (Fe) and impurities caused by melting, the latter having a total content of not greater than 2.5 percent by mass, each containing a total of 100 percent by mass. Alternatively, the antifriction bearing element according to the invention can be made of an austenitic steel having a composition of 16-21% by weight of chromium, 16-21% by weight of manganese, either greater than 2% by mass of molybdenum or less than or equal to 2% by mass of copper, or greater than or equal to 2% by mass of molybdenum and 0, 25 to 2% by mass of copper, and more than 0.5% in total by weight of carbon and nitrogen, wherein the ratio of carbon to nitrogen is greater than 0.5, up to 2.5% by weight of impurities caused by melting and a balance of iron by weight, the sum of all ingredients 100 percent by mass, be formed.

Four examples of concrete compositions of the aforementioned steel are given in the following table. The data refer in each case to percent by mass.

In addition, each of a residue of iron (Fe) and melting impurities, the latter having a total content of up to 2.5 percent by mass, contain, so that in each case a total of 100 percent by weight.

The mentioned steels are characterized, as mentioned, on the one hand by a good corrosion resistance on the part of the house, however, these show from the very beginning a comparatively low wear resistance. Essential to the present invention is the high solubility of the steels for impurities. Accordingly, it is possible that, under suitable conditions, foreign atoms, in particular carbon and / or nitrogen, can diffuse into the microstructure of the steels. In this way, the initially mentioned carbon and / or nitrogen-containing edge layer can be formed in the edge or near-surface regions of the roller bearing element.

The carbon and / or nitrogen-containing edge layer formed by the diffusion of carbon and / or nitrogen into the microstructure results in a type of solid solution hardening in the region of the surface layer, which in particular is due to an expansion of the austenitic microstructure through the introduction of the carbon and / or nitrogen atoms is due. Such a high hardness of the surface layer is given.

A microstructural change of the rolling bearing element in the region of carbon and / or nitrogen-containing surface layer formed as described is generally not given because the diffused into the steels impurities carbon and / or nitrogen there especially as interstitial atoms between the actual lattice sites of the microstructure present or are arranged. Consequently, the austenitic microstructure of the steels also essentially remains in the area of the carbon and / or nitrogen-containing boundary layer formed. In principle, the boundary layer containing carbon and / or nitrogen can be delimited from the remaining structural material of the rolling bearing element by corresponding carbon atoms and / or nitrogen atoms arranged on interstitial sites. The carbon and / or nitrogen-containing edge layer can also be understood as the region of the rolling bearing element in which an additional diffusion of carbon dioxide is achieved by carrying out the at least one measure for the diffusion of carbon and / or nitrogen into surface regions of the rolling bearing element. len and / or nitrogen, wherein the diffused carbon atoms and / or nitrogen atoms are preferably located on interstitial sites. The difference between the carbon and / or nitrogen-containing surface layer and the rest of the structure of the rolling bearing element is particularly evident in the microsection.

The thus-formed carbon and / or nitrogen-containing surface layer is also largely free of precipitates. The corrosion resistance of the steel-improving alloying elements such as, in particular, chromium (Cr), molybdenum (Mo) or nitrogen (N) are not or only slightly bound in carbide or nitride compounds by the additional introduction or penetration of carbon and / or nitrogen. Accordingly, the incorporation of carbon and / or nitrogen to form the carbon and / or nitrogen-containing surface layer does not significantly affect the corrosion resistance of the steels.

In particular, it may even be possible to improve the corrosion resistance in the region of the carbon and / or nitrogen-containing surface layer, which is achieved by introducing additional nitrogen and / or forming a stable passive layer which ensures passivation against corrosive media in the sense of additional surface passivation of the rolling bearing element can be explained. Corresponding experiments showed z. B. that by the formation of a carbon-containing surface layer, a significant improvement in corrosion resistance compared to a 3.5% NaCl solution is possible. Compared to samples without a corresponding surface layer, an increase of the pitting corrosion potential from 500 mV (vs. Ag / AgCl) to almost 1 V was measured for samples with a carbon-containing surface layer. A roller bearing element according to the invention is to be understood, for example, as a rolling bearing ring, a roller body rolling between corresponding roller bearing rings or a roller body cage for receiving corresponding rolling bodies. With reference to roller bearing elements which are present as rolling bearing rings, the edge zone containing carbon and / or nitrogen is formed at least in sections, in particular completely, on the outer and / or inner circumference of the rolling bearing ring and, in particular, in the region of the rolling bearing ring that is highly stressed during operation and encompasses the rolling body raceways ,

Incidentally, the boundary layer containing carbon and / or nitrogen can be delimited from the remaining material of the rolling bearing element in such a way that it has a comparatively higher proportion of carbon and / or nitrogen. B. can be represented by micrographs.

The carbon and / or nitrogen-containing edge layer is inventively formed by at least one measure for the diffusion of carbon and / or nitrogen in near-surface regions of the rolling bearing element. Consequently, depending on the particular measure selected in the context of the measure for the diffusion of carbon and / or nitrogen into near-surface regions of the rolling bearing element, it is possible to diffuse carbon and / or nitrogen into near-surface regions of the rolling bearing element or the respective process parameters used in this context z. As temperature, pressure, duration, concentration of carbon and / or nitrogen content of any necessary carbon and / or nitrogen atmosphere targeted influence on the trainees or trained carbon and / or nitrogen-containing edge layer of the rolling bearing element are taken. In particular, the penetration depth of the carbon and / or nitrogen atoms and the concentration of the carbon and / or nitrogen atoms in the carbon and / or nitrogen-containing surface layer can be influenced or controlled in terms of process technology. For example, it is possible in the implementation of the measure for the diffusion of carbon and / or nitrogen in the near-surface regions of the rolling bearing element to form the carbon and / or nitrogen-containing edge layer, by setting a suitable temperature, ie in particular a temperature below 500 ° C, no risk of negatively affecting the mechanical properties of the austenitic steel forming the rolling bearing element, in particular due to the temperature-induced migration of dislocations. As a result, the mechanical properties such as hardness, wear resistance, roll resistance etc. of the steel used can essentially be retained.

Furthermore, by a suitable, relatively low process temperature and a negative effect on the dimensions or dimensions and the surface quality, ie in particular the roughness of Wälzlager- elements excluded or recorded only to a minor extent.

As a corresponding measure for the diffusion of carbon and / or nitrogen in near-surface regions of the rolling bearing element is in particular a thermochemical treatment of the rolling bearing element in question, that is, the diffusion of carbon and / or nitrogen to form the carbon and / or nitrogen-containing edge layer is advantageously based on a Ther- chemical treatment of the rolling bearing element.

By a suitable process selection and process control of the at least one measure for the diffusion of carbon and / or nitrogen into near-surface regions of the rolling bearing element for forming the carbon and / or nitrogen-containing surface layer, this particular hardening in the range of 800 - 1500 HV (Vickers hardness), in particular greater than 900 HV. Basically, the highest possible hardnesses of the carbon and / or nitrogen-containing surface layer should be sought, since they have a significant influence on the wear resistance of the rolling bearing element. Of course, the hardness of the carbon and / or nitrogen can be retaining boundary layer in exceptional cases or in sections below 800 HV or above 1500 HV.

Similarly, the layer thickness can be adjusted by suitable process selection and process control of the at least one measure for the diffusion of carbon and / or nitrogen into near-surface regions of the rolling bearing element to form the carbon and / or nitrogen-containing edge layer. The carbon and / or nitrogen-containing surface layer may accordingly have, for example, a layer thickness of from 1 to 50 μm, preferably from 2.5 to 40 μm, particularly preferably from 5 to 25 μm. Of course, the layer thickness of the carbon and / or nitrogen-containing surface layer may in exceptional cases or in sections also be below 2.5 μm or above 40 μm. The rolling bearing element according to the invention can be prepared by the method described below for producing a rolling bearing element, in particular a rolling bearing ring, with a carbon and / or nitrogen-containing surface layer, which also represents a part of the present invention.

The method according to the invention comprises the steps:

Providing an austenitic steel rolling bearing element having a composition of 16 to 21% by mass of chromium, 16 to 21% by mass of manganese, 0.5 to 2.0% by mass of molybdenum, in total 0.8 to 1.1% by mass of carbon and nitrogen, said The ratio of carbon to nitrogen is 0.5 to 1.1, up to 2.5% by weight of impurity-causing impurities and a balance of iron by weight, the sum of all constituents being 100% by mass, or

Providing a rolling bearing element made of an austenitic steel, more preferably a composition of 16-21% by weight of chromium, 16-21% by weight of manganese, either greater than 2% molybdenum by weight or less than 2% copper by weight, or greater than 2% molybdenum by mass and 0.25 to 2% copper by weight, and more than 0.5% carbon and nitrogen in total, wherein the ratio of carbon to nitrogen is greater than 0.5, up to 2.5% by weight of impurities caused by melting and a balance of iron by mass, wherein the sum of all components is 100 percent by mass, and

- Performing at least one measure for the diffusion of carbon and / or nitrogen in near-surface regions of the rolling bearing element to form the carbon and / or nitrogen-containing surface layer. The above-mentioned embodiments generally apply to the rolling bearing element according to the invention, that is, in particular all embodiments in connection with the carbon and / or nitrogen-containing surface layer or their formation, that is, the or the measures for the diffusion of carbon and / or nitrogen in near-surface regions of the rolling bearing element analog.

As a measure for forming the carbon and / or nitrogen-containing surface layer, a thermochemical treatment of the rolling bearing element is preferably carried out. For this purpose, in particular the following processes for the diffusion of carbon and / or nitrogen into edge or near-surface areas of the rolling bearing element in question: Kolsterisieren, plasma carburizing, plasma nitriding, gas nitriding, gas nitrocarburizing. If necessary, the processes can also be combined or carried out sequentially.

Kolsterizing is generally understood to mean a diffusion of carbon into the material to be treated at temperatures below 300 ° C., whereby the carbon is dissolved in interstices of the starting material, resulting in compressive stresses and thus in a high hardness (greater than 1000 HV (Vickers hardness)). leads. A plasma carburization is used with the use of a plasma for the diffusion of carbon into edge or near-surface areas of the material to be carburized. Similarly, a high hardness can be achieved in such a way due to the introduction of attributable to the incorporation of carbon compressive stresses.

The same applies essentially to a plasma nitriding, whereby here of course not carbon, but nitrogen is diffused into the starting material to be treated.

Gas nitriding is a thermochemical process in which the material to be treated, that is in particular to be cured tempered while a nitrogen-containing gas such. B. ammonia (NH ₃ ) is exposed, which then leads to the diffusion of nitrogen into the starting material.

In gas nitrocarburizing, in which a diffusion of carbon and nitrogen is achieved in the material to be treated, the material to be treated in addition a carbon-containing gas such. B. CO ₂ , that is a total of a gas mixture of a nitrogen and a carbon-containing gas exposed and tempered accordingly.

As part of experiments to form the carbon and / or nitrogen-containing surface layer of corresponding rolling bearing elements showed that plasma nitriding particularly good results in terms of the formation of a nitrogen-containing surface layer of corresponding rolling bearing elements can be achieved.

It is advantageous if the thermochemical treatment is carried out in a temperature range from 250 to 550.degree. C., in particular below 500.degree. C., preferably below 450.degree. C. or of 400.degree. By adjusting the temperature applied during the thermochemical treatment, it is possible to have a specific influence on the kinetics of the diffusion of carbon and / or nitrogen are taken in the edge or surface area of Wälzlagerele- element and thus targeted a certain range of properties of the carbon and / or nitrogen-containing surface layer to be formed can be adjusted. Due to the comparatively low temperatures, temperature-related influences on the dimensional stability and / or surface quality or roughness of the rolling bearing element can be excluded or at least kept to a tolerable extent. Of course, the thermo-chemical treatment in exceptional cases and / or temporarily below 200 ° C or above 550 ° C can be performed.

The thermochemical treatment can be carried out in particular for a period of two to 24 hours, in particular 4 to 16 hours. Similar to the setting of the temperature applied in the course of carrying out the thermochemical treatment, it is also possible to influence the diffusion of carbon and / or nitrogen into the edge or surface area of the rolling bearing element by adjusting the duration or process time specifically a certain property spectrum of the carbon and / or nitrogen-containing surface layer to be formed can be set. Of course, in exceptional cases, the thermochemical treatment can also be carried out for less than two hours or longer than 24 hours.

In principle, the measure for forming the carbon and / or nitrogen-containing surface layer can be carried out such that a carbon and / or nitrogen-containing surface layer having a layer thickness of 1 to 50 μm, preferably from 2.5 to 40 μm, particularly preferably from 5 to 25 μιτι, trains. In exceptional cases, the layer thickness of the carbon and / or nitrogen-containing surface layer may also lie below 1 μm or above 40 μm.

It is possible within the scope of the method according to the invention for the carbon to be carried out before the at least one measure is carried out and / or nitrogen-containing edge layer at least one measure for work hardening, in particular cold forming, of the rolling bearing element is performed. Under the measures for cold work hardening of a metallic material cold forming is the plastic deformation of metallic materials at a temperature well below their respective recrystallization temperature to understand. The plastic deformation of the material increases the dislocation density within the material and thus causes an increase in hardness. In this way, the mechanical properties of the roller bearing element can be increased even before the at least one measure for the diffusion of carbon and / or nitrogen into near-surface regions of the rolling bearing element to form the carbon and / or nitrogen-containing edge layer is carried out in the context of the method according to the invention then, that is after the implementation of the at least one measure for the diffusion of carbon and / or nitrogen in near-surface regions of the rolling bearing element for forming the carbon and / or nitrogen-containing edge layer again increased or improved.

Short description of the drawing

An embodiment of the invention is illustrated in the drawing and will be described in more detail below. 1 shows a rolling bearing, comprising a plurality of rolling bearing elements according to an exemplary embodiment of the invention and

Figure 2 enlargement of the detail shown in Figure 1.

Detailed description of the drawing FIG. 1 shows a roller bearing 1 comprising a plurality of roller bearing elements 2 according to an exemplary embodiment of the invention. Obviously, the rolling bearing 1 is present as a ball bearing. The rolling bearing elements 2 are formed as rolling bearing rings 3, 4 between which rolling elements 5 roll.

The rolling bearing elements 2 designed as rolling bearing rings 3, 4 are made of an austenitic steel, which steel has a composition of 16-21% by mass of chromium, 16-21% by mass of manganese, 0.5-2.0% by mass of molybdenum, in total 0.8-1, 1 mass% of carbon and nitrogen, wherein the ratio of carbon to nitrogen is 0.5 to 1.1, 0.1 to 2.5 mass% of impurities caused by melting and a balance of mass of iron, the sum of all constituents being 100 mass% , Alternatively, one of the rolling bearing elements 2 or both rolling bearing elements 2 may also be made of an austenitic steel having a composition of 16-21% chromium, 16-21% manganese, either greater than 2% molybdenum or less than 2% copper by weight, or greater than 2% by mass Molybdenum and 0.25 to 2% by weight of copper, and more than 0.5% in total by weight of carbon and nitrogen, wherein the ratio of carbon to nitrogen is greater than 0.5, 0.1 to 2.5% by weight of impurities and a balance in mass percent of iron, wherein the sum of all constituents is 100 percent by mass.

Concrete compositions of exemplary austenitic steels can be found in the tables above.

The inner or outer peripheries of the roller bearing elements 2 which form or cover the running surfaces for the rolling bodies 5 have a feature of at least one measure for the diffusion of carbon and / or nitrogen into them Near-surface regions of the rolling bearing element formed nitrogen and / or carbon-containing edge layer 6.

The carbon and / or nitrogen-containing edge layer 6 can be seen particularly clearly from the enlarged view of the detail shown in Figure 1 Figure 2. It turns out that a carbon and / or nitrogen-containing edge layer 6 has formed with a substantially homogeneous layer thickness d. The carbon and / or nitrogen-containing edge layer 6 has, for example, a layer thickness d of about 20 μιτι. The austenitic basic structure 7 of the rolling bearing element 2 forming steel is also shown.

The edge layer 6 is formed, in particular, by means of a thermochemical treatment or a thermochemical process for the diffusion of carbon and / or nitrogen into regions of the roller bearing elements 2 which are close to the edges or near the surface. For example, the surface layer is formed by plasma annealing or plasma nitriding.

The carbon and / or nitrogen-containing edge layer 6 therefore has a high hardness of more than 1000 HV, in particular in the range of 1200 HV, and, in particular, interstitial sites of the original microstructure 7 of the respective austenitic steel in terms of interstitial atoms thus an excellent wear resistance.

The bond between the carbon and / or nitrogen-containing edge layer 6 and the remaining material or basic structure 7 of the respective rolling bearing element 2 is very good, since the carbon and / or nitrogen-containing edge layer 6 is not applied as a coating on the rolling bearing element 2, but directly from the steel bearing element 2 forming steel or basic structure 7 of the steel was formed. A corresponding rolling bearing element 2 can be produced, for example, by a manufacturing method described below for producing a rolling bearing element 2, in particular a rolling bearing ring 3, 4, with a boundary layer 6 containing carbon and / or nitrogen.

According to the method, first, a rolling bearing element 2 made of a austenitic steel having a composition of 16-21% by mass of chromium, 16-21% by mass of manganese, 0.5% to 2.0% by mass of molybdenum, in total 0.8-1.1% by mass Carbon and nitrogen, wherein the ratio of carbon to nitrogen is 0.5 to 1.1, 0.1 to 2.5 mass% of impurities caused by melting and a balance of mass of iron, the sum of all constituents being 100 mass% , provided. It is also conceivable to provide a rolling bearing element 2, made of an austenitic steel, which has a composition of 16-21% by weight of chromium, 16-21% by weight of manganese, either greater than 2% molybdenum by weight or less than or equal to 2% by mass copper, or greater than or equal to 2% by mass molybdenum and zero , 25 to 2% by mass of copper, and more than 0.5% in total by weight of carbon and nitrogen, wherein the ratio of carbon to nitrogen is greater than 0.5, 0.1 to 2.5% by mass of impurities caused by fusion and a balance of iron by mass, wherein the sum of all components is 100 percent by mass.

Concrete compositions of exemplary austenitic steels can, as mentioned, be taken from the above-mentioned tables.

After provision of the rolling bearing element 2, at least one measure would be taken to diffuse carbon and / or nitrogen into areas of the rolling bearing element 2 near the surface to form the carbon and / or nitrogen-containing edge layer 6. As a measure for forming the carbon and / or nitrogen-containing edge layer 6 while a thermochemical treatment of the rolling bearing element 2 is performed. The thermochemical treatment of the rolling bearing element 2 takes place in particular in the form of colosting and / or plasma carburizing and / or plasma nitriding and / or gas nitriding and / or gas nitrocarburizing.

In order not to adversely affect the dimensions and the surface quality, ie in particular the roughness of the rolling bearing element 2, the thermochemical treatment at low temperatures in a temperature range of 250 to 550 ° C, in particular below 500 ° C, performed.

The thermochemical treatment of the rolling bearing element 2 is typically carried out for a period of two to 24 hours, in particular 4 to 16 hours. In this way it is possible to regularly form layer thicknesses d of the corresponding carbon and / or nitrogen-containing edge layers 6 from 1 to 50 μm, preferably from 2.5 to 40 μm, particularly preferably from 5 to 25 μm. It is possible that at least one measure for work hardening, in particular cold forming, of the rolling bearing element 2 is carried out prior to carrying out the at least one measure for forming the carbon and / or nitrogen-containing edge layer 6, that is to say before carrying out the thermochemical treatment of the rolling bearing element 2 , This Ka Itverfestigungsschritt may also be an integral part of the process according to the invention. In this way, the property profile, that is to say in particular the mechanical properties of the roller bearing element 2, can already be improved before the at least one measure for forming the carbon and / or nitrogen-containing edge layer 6 is carried out. This combination of measures leads to a particularly advantageous component. The material according to the invention causes the corrosion resistance, the work hardening (to 650 - 730 HV) causes the roller bearing roll over resistance, while the surface treatment causes the wear resistance. In contrast to martensites and standard austenites, the austenite "carnit" can gain in hardness, at least in the surface layer, to a depth of approximately 1.5 mm up to 300 V. In contrast to martensites, a largely precipitate-free surface layer of approx The high solubility of interstitial atoms in many austenites is typical in the case of the material used according to the invention because of its high Mn content, which, in contrast to many martensites and some austenites, reduces the hardness due to Erho - Lung in the thermochemical edge treatment in the temperature range of 250 - 550 ° C not, so that an excellent properties exhibiting rolling bearing element is obtained.

LIST OF REFERENCE NUMBERS

roller bearing

Rolling element

roller bearing ring

rolling elements

Carbon and / or nitrogen-containing surface layer

microstructure

Claims

claims

Roller bearing element (2), in particular rolling bearing ring (3, 4), which roller bearing element (2) made of an austenitic steel, which has a composition of 16-21% by mass of chromium, 16-21% by mass of manganese, 0.5-2.0% by mass of molybdenum, in total 0.8 to 1, 1 percent by mass of carbon and nitrogen, wherein the ratio of carbon to nitrogen 0.5 to 1, 1, up to 2.5 percent by mass of impurities caused by melting and a balance of iron by mass, the sum of all components is 100 Mass percent results, has, is formed, characterized in that it comprises by at least one measure for the diffusion of carbon and / or nitrogen in near-surface regions of the rolling bearing element (2) formed carbon and / or nitrogen-containing edge layer (6).

Rolling bearing element (2), in particular rolling bearing ring (3, 4), which rolling bearing element (2) austenitic steel, which has a composition of 16-21 percent by mass of chromium, 16-21 percent by mass of manganese, either greater than 2 percent by mass of molybdenum or less than 2 percent by mass of copper , or greater than or equal to 2% by mass of molybdenum and 0.25 to 2% by weight of copper, and more than 0.5% by weight of carbon and nitrogen in total, wherein the ratio of carbon to nitrogen is greater than 0.5, up to 2.5% by weight of impurities caused by melting and a remainder of mass percent of iron, the sum of all constituents being 100 mass percent, characterized, characterized in that it comprises a carbon formed by at least one measure for the diffusion of carbon and / or nitrogen into near-surface areas of the rolling bearing element (2) / or nitrogen-containing edge layer (6). Rolling element according to claim 1 or 2, characterized in that the carbon and / or nitrogen-containing edge layer (6) has a hardness of 800 - 1500 HV, in particular greater than 900 HV.

Rolling element according to one of the preceding claims, characterized in that the carbon and / or nitrogen-containing edge layer (6) has a layer thickness (d) of 1 to 50 μιτι, preferably from 2.5 to 40 μιτι, particularly preferably from 5 to 25 μιτι, having.

Method for producing a roller bearing element (2), in particular a roller bearing ring (3, 4), with a carbon and / or nitrogen-containing edge layer (6), characterized by the steps:

- Providing a rolling bearing element (2) made of an austenitic steel, which has a composition of 16 - 21 percent by weight of chromium, 16 - 21 percent by mass of manganese, 0.5 to 2.0 percent by mass of molybdenum, in total 0.8 to 1, 1 percent by mass of carbon and nitrogen wherein the ratio of carbon to nitrogen is 0.5 to 1.1, up to 2.5% by weight of impurities caused by melting and a balance of iron by mass, the sum of all constituents being 100% by mass, or

Providing an antifriction bearing element (2) made of an austenitic steel having a composition of 16-21% by weight of chromium, 16-21% by weight of manganese, either greater than 2% by mass of molybdenum or less than or equal to 2% by mass of copper, or greater than or equal to 2% by mass of molybdenum and 0, 25 to 2% by mass of copper, and more than 0.5% in total by weight of carbon and nitrogen, wherein the ratio of carbon to nitrogen is greater than 0.5, up to 2.5% by weight of impurities caused by melting and a balance of iron by weight, the sum of all constituents 100 percent by mass,

Performing at least one measure for the diffusion of carbon and / or nitrogen into near-surface areas of the rolling bearing element ment (2) for forming the carbon and / or nitrogen-containing surface layer (6).

A method according to claim 5, characterized in that as a measure for forming the carbon and / or nitrogen-containing edge layer (6), a thermochemical treatment of the rolling bearing element (2) is performed.

A method according to claim 6, characterized in that the thermochemical treatment in a temperature range of 250 to 550 ° C, in particular below 500 ° C, is performed.

A method according to claim 6 or 7, characterized in that the thermochemical treatment for a period of two to 24 hours, in particular 4 to 16 hours, is performed.

Method according to one of claims 6 to 8, characterized in that the measure for forming the carbon and / or nitrogen-containing edge layer (6) is performed such that a carbon and / or nitrogen-containing edge layer (6) with a layer thickness (i.e. ) from 1 to 50 μιτι, preferably from 2.5 to 40 μιτι, more preferably from 5 to 25 μιτι, forms.

Method according to one of claims 6 to 9, characterized in that as a measure to form the nitrogen and / or carbon-containing surface layer (6) Kolsterisieren and / or plasma carburizing and / or plasma nitriding and / or gas nitriding and / or Gasnitrocarbu- is performed.