# US 5,705,124 A · High carbon bearing steel having a long life

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,705,124 A
- Document ID: US5705124A
- Status: Granted
- Kind: A
- Application number: 08/591,451
- Filed: 1996-01-31
- Granted: 1998-01-06
- Earliest claimed: 1994-06-16
- Assignees: Nippon Steel Corporation
- Inventors: Tatsuro Ochi; Yuji Kawauchi
- Web page: https://patentgrep.com/patent/US5705124A

## CPC

- C22C 38/22: with molybdenum or tungsten
- F16C 33/62: Selection of substances
- F16C 2204/66: High carbon steel, i.e. carbon content above 0.8 wt%, e.g. through-hardenable steel
- Y10S 148/906: Roller bearing element
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The present invention is intended to provide a high carbon bearing steel, for bearing parts, excellent in rolling fatigue characteristics. A high carbon bearing steel having a long life comprising 0.70 to 1.20% of C, 0.15 to 1.70% of Si, 0.15 to 1.20% of Mn, 0.50 to 2.00% of Cr, 0.05 to 1.50% of Mo, 0.001 to 0.03% of S, 0.010 to 0.05% of Al, 0.003 to 0.015% of N, 0.0005 to 0.0300% of total Mg, up to 0.025% of P, up to 0.0040% of Ti, up to 0.0015% of total oxygen, one or at least two elements selected from V, Nb and Ni in specific amounts, and having a number ratio of Mg oxides contained therein of at least 0.8.

## Claims

### Claim 1

A high carbon bearing steel having a long life which comprises, in terms of weight, 0.70 to 1.20% of C, 0.15 to 1.70% of Si, 0.15 to 1.20% of Mn, 0.50 to 2.00% of Cr, 0.05 to 1.50% of Mo, 0.001 to 0.03% of S, 0.010 to 0.05% of Al, 0.003 to 0.015% of N, 0.0005 to 0.0300% of total Mg, up to 0.025% of P, up to 0.0040% of Ti, up to 0.0015% of total oxygen and the balance Fe and unavoidable impurities.

### Claim 2

A high carbon bearing steel having a long life which comprises, in terms of weight, 0.70 to 1.20% of C, 0.15 to 1.70% of Si, 0.15 to 1.20% of Mn, 0.50 to 2.00% of Cr, 0.05 to 1.50% of Mo, 0.001 to 0.03% of S, 0.010 to 0.05% of Al, 0.003 to 0.015% of N, 0.0005 to 0.0300% of total Mg, one or at least two elements selected from the group consisting of the following elements in the following amounts: 0.03 to 0.7% of V, 0.005 to 0.3% of Nb and 0.10 to 2.00% of Ni, up to 0.025% of P, up to 0.0040% of Ti, up to 0.0015% of total oxygen and the balance Fe and unavoidable impurities.

### Claim 3 (depends on 1)

The high carbon bearing steel having a long life according to claim 1, wherein the number ratio of oxides contained therein satisfies the formula
(number of MgO.Al.sub.2 O.sub.3 +number of MgO)/(number of total oxide inclusions).gtoreq.0.80.
4.

### Claim 4 (depends on 2)

The high carbon bearing steel having a long life according according to claim 2 wherein the number ratio of oxides contained therein satisfies the formula
(number of MgO.Al.sub.2 O.sub.3 +number of MgO)/(number of total oxide inclusions).gtoreq.0.80.