Method for producing a rolling bearing ring having an improved robustness against the formation of white etching cracks (WEC)

Patent metadata

Field	Value
Publication number	US-11624403-B2
Application number	US-201716347309-A
Country	US
Kind code	B2
Filing date	Nov 7, 2017
Priority date	Nov 9, 2016
Publication date	Apr 11, 2023
Grant date	Apr 11, 2023

Abstract

The invention relates to a method for producing a rolling bearing ring featuring an improved robustness against the formation of white etching cracks (WEC), wherein the rolling bearing component, which is made of a hypo-eutectoid heat-treated steel containing C in an amount of 0.4-0.55% and Cr in an amount of 0.5-2.0% in order to form a hardened boundary layer, is inductively heated, then quenched and subsequently tempered.

First claim

The invention claimed is:

1. A method for producing a rolling bearing ring, wherein the rolling bearing ring, which is made of a hypo-eutectoid heat-treated steel containing:
C: 0.45% by mass;
Si: 0.23% by mass;
Mn: 0.64% by mass;
P: 0.004% by mass;
S: 0.001% by mass;
Cr: 1.18% by mass;
Mo: 0.28% by mass;
Ni: 0.75% by mass;
Cu: 0.12% by mass;
Al: 0.02% by mass;
as well as a rest of iron and trace elements in order to form a hardened boundary layer, is inductively heated, then quenched and subsequently tempered, wherein the inductive heating is carried out at a frequency of 9-10 kHz, for a period of 4-7 s, wherein the hardened boundary layer lacks undissolved carbides after quenching and during tempering carbides are formed having a size less than 1 μm, wherein the tempering is carried out at a temperature ranging from 130-150° C. for a duration of 2-3 h, wherein a residual compressive stress of at least 300 MPa is provided in the hardened boundary layer, and
wherein a structure beneath the hardened boundary layer consists of lath martensite.

2. The method according to claim 1 , wherein the hardened boundary layer has a thickness ranging from at least 0.2 mm thickness to up to a maximum of 8 mm.

3. A method of producing a rolling bearing ring for a rolling bearing, the method comprising:
producing a rolling bearing ring having a steel containing:
C: 0.45% by mass;
Si: 0.23% by mass;
Mn: 0.64% by mass;
P: 0.004% by mass;
S: 0.001% by mass;
Cr: 1.18% by mass;
Mo: 0.28% by mass;
Ni: 0.75% by mass;
Cu: 0.12% by mass;
Al: 0.02% by mass;
as well as a rest of iron and trace elements;

inductively heating the steel at a frequency of 8-11 kHz for a period of 3-10 s; and
then quenching and tempering the steel to form a hypo-eutectoid heat-treated steel with a hardened boundary layer,
wherein the hardened boundary layer lacks undissolved carbides after quenching and during tempering carbides are formed having a size less than 1 μm;
wherein the tempering is carried out at a temperature ranging from 120-180° C. for a duration of 1-4 h, wherein a residual compressive stress of at least 300 MPa is provided in the hardened boundary layer;
wherein a structure beneath the hardened boundary layer consists of lath martensite.

4. The method of claim 3 , wherein the step of inductively heating is performed at a frequency 9-10 kHz.

5. The method of claim 3 , wherein the step of inductively heating is performed for a period of 4-7 s.

6. The method of claim 3 , wherein the tempering is carried out at a temperature ranging from 130-150° C.

7. The method of claim 3 , wherein the tempering is carried out for a duration of 2-3 hours.

Assignees

• Schaeffler Technologies Ag

Inventors

• Hofmann Lothar
• Mangold Andreas
• Blass Toni
• Kruhoeffer Wolfram
• Trojahn Werner

Classifications

• Y02P10/25

  Process efficiency · CPC title

• C22C38/06

  containing aluminium · CPC title

• C21D9/38

  for roll bodies · CPC title

• C22C38/44

  with molybdenum or tungsten · CPC title

• C22C38/02

  containing silicon · CPC title