BEARING COMPONENT HAVING A METALLIC BASE BODY AND AN ALLOY- STEEL COATING

Abstract

A bearing component such as a bearing ring includes a metallic base body and at least one alloy steel coating on the base body, the coating being applied to the base body by deposition welding. The base body is preferably non-alloy steel or cast iron, and the alloy includes at least one carbide-forming transition metal such as niobium, tantalum, zirconium, titanium, hafnium, tungsten, molybdenum, vanadium, or manganese. The coating can form a raceway of the bearing component or a structural element such as a flange. Also a method of forming such a bearing component is provided.

Claims

1. A bearing component including: a metallic base body, and at least one alloy steel coating on the base body, wherein the coating is applied to the base body by deposition welding.

2. The bearing component according to claim 1, wherein the base body comprises a material selected from the group consisting of: non-alloy steel, cast iron, an aluminum alloy, a titanium alloy and a copper alloy.

3. The bearing component according to claim 1, wherein the base body comprises non-alloy steel or cast iron.

4. The bearing component according to claim 1, wherein the at least one alloy steel coating comprises an alloy of a base steel and at least one carbide-forming transition metal.

5. The bearing component according to claim 4, wherein the at least one carbide-forming transition metal is selected from the group consisting of: niobium, tantalum, zirconium, titanium, hafnium, tungsten, molybdenum, vanadium, and manganese.

6. The bearing component according to claim 4, wherein the at least one carbide-forming transition metal is selected from the group consisting of niobium, tantalum, and zirconium.

7. The bearing component according to claim 4, wherein the at least one alloy steel coating contains between 0.01 wt. % and 5 wt. % of the carbide-forming transition metal, wherein the base steel of the at least one alloy steel coating is an overrolling-resistant steel, and wherein the carbide-forming transition metal includes a) between 1.5 and 2.5 wt. % zirconium, or b) between 0.5 and 1.5 wt. % niobium, or c) between 2.5 and 3.5 wt. % tantalum.

8. The bearing component according to claim 4, wherein the at least one alloy steel coating contains between 1 wt. % and 3 wt. % of the carbide-forming transition metal, wherein the at least one alloy steel coating includes a rolling-element-bearing steel as the base steel, and wherein the carbide-forming transition metal includes a) 2 wt. % zirconium, or b) 1 wt. % niobium, or c) 3 wt. % tantalum.

9. The bearing component according to claim 8, wherein the rolling-element bearing steel is selected from the group consisting of 100Cr6, 100CrMnSi6-4, 100CrMo7-3 and 100CrMnMoSi84-6.

10. The bearing component according to claim 4, wherein the base steel includes: 0.25 to 1.3 wt. % carbon, 0.1 to 1.0 wt. % silicon, 0.1 to 1.5 wt. % manganese, and 0.5 to 2.5 wt. % chromium.

11. The bearing component according to claim 10, wherein the base steel includes one or more of the following elements: 0 to 1.0 wt. % molybdenum, 0 to 4.0 wt. % nickel, 0 to 0.5 wt. % copper, 0 to 0.1 wt. % aluminum, 0 to 0.1 wt. % calcium, 0 to 0.1 wt. % vanadium, 0 to 0.1 wt. % titanium, 0 to 0.1 wt. % niobium, 0 to 0.1 wt. % tantalum, 0 to 0.1 wt. % tungsten, 0 to 0.1 wt. % cobalt, 0 to 0.1 wt. % nitrogen, 0 to 0.1 wt. % oxygen, 0 to 0.1 wt. % boron, 0 to 0.05 wt. % phosphorus, 0 to 0.05 wt. % sulfur, and 0 to 0.05 wt. % tin, the remainder being iron and unavoidable impurities.

12. The bearing component according to claim 1, wherein the bearing component comprises a bearing ring and the coating is formed as a raceway, a structure or a flange of the bearing ring.

13. A method of forming a bearing component comprising: providing a metallic base body; and applying at least one alloy steel coating on the base body by deposition welding.

14. The method according to claim 13, wherein the alloy steel coating comprises a base steel and at least one carbide-forming transition metal.

15. The method according to claim 14, wherein the method includes, during or after applying the at least one alloy steel coating, performing a) at least one reshaping treatment at a temperature between 500 and 1400 C. and/or b) a heat treatment at a temperature between 500 and 1200 C., to generate particles of carbides, carbonitrides, and/or nitrides of the transition metal by a deformation-induced and/or thermal precipitation, with or without previous solution annealing.

16. The method according to claim 15, including mixing the base steel and the at least one carbide-forming transition metal during the deposition welding.

17. The method according to claim 15, wherein the base steel and the at least one carbide-forming transition metal are provided in the form of a powder.

18. A bearing ring comprising: a core composed of non-alloy steel that comprises up to 0.4 wt % carbon; and a cladding fused to a raceway surface of the core, the cladding being composed of a steel that comprises 0.8-1.2 wt % carbon and 1-3 wt. % of at least one carbide-forming transition metal.

19. The bearing ring according to claim 18, wherein: the non-alloy steel has a composition (in wt. %) of C: 0.4, Mn: 1.60, Ni: 0.4, P: 0.05, S: 0.05, Si: 0.4, Cr: 0.4, Mo: 0.1, N: 0.009, the remainder being iron and unavoidable impurities; and the cladding has a composition (in wt. %) of C: 0.93-1.05, Si: 0.15-0.75, Mn: 0.25-1.20, P: 0.025, S: 0.015, Cr: 1.35-2.05, Mo: 0.060, Al: 0.050, Cu: 0.30, and a total of 1-3 wt. % of the at least one carbide-forming transition metal, which is selected from the group consisting of Nb, Ta, and Zr, the remainder being iron and unavoidable impurities.

20. The bearing ring according to claim 19, wherein: the cladding has a thickness that is between 1-10% of a total thickness of the core and the cladding; the core and the cladding each contain at least 70% volume percent martensitic and/or bainitic microstructure; the cladding contains between 1-10 volume % of carbide-transition metal particles; the carbide-transition metal particles in the cladding have a number-weighted average particle size of 1 micron or less; and the at least one carbide-forming transition metal includes at least Zr.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0051] FIG. 1 is a schematic cross-sectional view of a rolling-element bearing according to the present disclosure.

DETAILED DESCRIPTION

[0052] In the following, identical or functionally equivalent elements are designated by the same reference numbers.

[0053] In FIG. 1 a rolling-element bearing 1 is illustrated that includes a bearing inner ring 2 having a raceway 9 and a bearing outer ring 3 having a raceway 10. Rolling elements 4 are disposed therebetween that roll on the raceways 9, 10.

[0054] The bearing inner ring 2 includes a base body (core) 5 that forms the bearing inner ring 2 and a metallic coating (cladding) 6 applied onto the base body 5, which metallic coating 6 forms the raceway for the rolling elements 4. Here the coating 6 is applied onto the base body 5 by deposition welding (cladding, e.g., laser cladding).

[0055] The base body 5 optionally may be manufactured from a non-alloy steel, for example, S235, S355, C22, or C35. In such embodiments of the present teachings, the base body 5 can be manufactured relatively cost-effectively due to the selection of a less expensive material for the core. The coating 6 itself includes an alloy steel, which enables the required hardness and rolling contact fatigue resistance to be achieved for the raceway 9.

[0056] According to one preferred exemplary embodiment the alloy of the coating 6 comprises the through-hardened rolling-element-bearing steel 100Cr6 as the base steel, and the transition metal zirconium in a concentration of 2.0 wt. % as a further component. This comparatively high proportion of the transition metal zirconium can be made possible in the alloy since the coating 6 is applied onto the base body 5 by the deposition welding process, wherein the alloy is formed in situ in the welding process. It is noted, for purposes of comparison, that such a high proportion of the transition metal can be achieved using known steel manufacturing techniques only with considerable technical effort.

[0057] The bearing outer ring 3 also may be formed in an analogous manner; in particular, the bearing outer ring 3 may include a base body 7 and a coating 8 that is applied in a similar manner onto the raceway of the bearing outer ring 3.

[0058] In summary a bearing component is provided that includes a base body and a coating, wherein the coating is distinguished by exhibiting a particularly high hardness and rolling wear resistance. Here the coating is formed on the base body in situ during a deposition welding process. In comparison to conventional melt-metallurgical steel manufacturing, with subsequent precipitation of carbides, carbonitrides, or nitrides, e.g., in the context of a heat treatment, using the inventive method, slag losses in particular can be more easily avoided during steel manufacturing.

[0059] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved bearing components having metallic base bodies and an alloy-steel coating.

[0060] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0061] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

REFERENCE NUMBER LIST

[0062] 1 Rolling-element bearing [0063] 2 Bearing inner ring [0064] 3 Bearing outer ring [0065] 4 Rolling element [0066] 5 Base body of the bearing inner ring [0067] 6 Coating of the bearing inner ring [0068] 7 Base body of the bearing outer ring [0069] 8 Coating of the bearing outer ring [0070] 9 Raceway of the bearing inner ring [0071] 10 Raceway of the bearing outer ring