# US 12,000,028 B2 · Rail vehicle axle

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- Number: US 12,000,028 B2
- Document ID: US12000028B2
- Status: Granted
- Kind: B2
- Application number: 15/751,020
- Filed: 2016-08-17
- Published: 2018-08-30
- Granted: 2024-06-04
- Earliest claimed: 2015-08-24
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel & Sumitomo Metal Corporation
- Inventors: Taizo Makino; Takayuki Kamimura; Yuichiro Yamamoto; Yutaka Wakasu; Kiyonobu Sugae; Yukiteru Takeshita; Naomitsu Mizui
- Web page: https://patentgrep.com/patent/US12000028B2

## CPC

- C22C 38/50: with titanium or zirconium
- B61F 5/50: Other details
- C21D 1/28: Normalising
- C21D 6/002: {containing Cr (C21D6/004 takes precedence)}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 8/06: during manufacturing of rods or wires
- C21D 9/08: for tubular bodies or pipes
- C21D 9/28: for plain shafts
- C22C 38/001: {containing N}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/008: {containing tin}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/08: containing nickel {(C22C38/105 takes precedence)}
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/14: containing titanium or zirconium
- C22C 38/16: containing copper
- C22C 38/18: containing chromium
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- F16C 3/02: Shafts; Axles
- F16C 2204/62: Low carbon steel, i.e. carbon content below 0.4 wt%
- F16C 2326/10: Railway vehicles
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B61F: RAIL VEHICLE SUSPENSIONS, e.g. UNDERFRAMES, BOGIES OR ARRANGEMENTS OF WHEEL AXLES; RAIL VEHICLES FOR USE ON TRACKS OF DIFFERENT WIDTH; PREVENTING DERAILING OF RAIL VEHICLES; WHEEL GUARDS, OBSTRUCTION REMOVERS OR THE LIKE FOR RAIL VEHICLES (for vehicles in general B60; axles or wheels B60B; vehicle tyres B60C)
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS

## Abstract

Provided is a rail vehicle axle having an excellent fatigue limit and notch factor. A rail vehicle axle according to the present embodiment has a chemical composition consisting of, in mass %, C: 0.20 to 0.35%, Si: 0.20 to 0.65%, Mn: 0.40 to 1.20%, P: 0.020% or less, S: 0.020% or less, Sn: 0.07 to 0.40%, N: 0.0200% or less, Cu: 0 to 0.30%, Ni: 0 to 0.30%, Cr: 0 to 0.30%, Mo: 0 to 0.08%, Al: 0 to 0.100%, V: 0 to 0.060%, and Ti: 0 to 0.020%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2): 0.58≤C+Si/8+Mn/5+Cu/10+Cr/4+V≤0.67 (1) Si+0.9Cr≥0.50 (2) where, each element symbol in Formulae (1) and (2) is substituted by the content (mass %) of a corresponding element.

## Claims

### Claim 1

A rail vehicle axle comprising:
a chemical composition consisting of, in mass %,
C: 0.20 to 0.35%,
Si: 0.20 to 0.65%,
Mn: 0.40 to 1.20%,
P: 0.020% or less,
S: 0.020% or less,
Sn: 0.21 to 0.40%,
N: 0.0200% or less,
Cu: 0 to 0.30%,
Ni: 0 to 0.30%,
Al: 0 to 0.100%,
V: 0 to 0.060%, and
one or more from the group consisting of Cr: more than 0.20 to 0.30%, Mo: 0.005 to 0.08%, and Ti: 0.002 to 0.020%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2):
0.58≤C+Si/8+Mn/5+Cu/10+Cr/4+V≤0.67 (1)
Si+0.9Cr≥0.60 (2)
where each element symbol in Formulae (1) and (2) is substituted by the content (mass %) of a corresponding element,
wherein the smooth fatigue limit is more than 270 MPa,
the notched fatigue limit is more than 195 MPa, and
a notch factor of the rail vehicle axle is not more than 1.47, where notch factor is defined by smooth fatigue limit divided by notched fatigue limit.

### Claim 2 (depends on 1)

The rail vehicle axle according to claim 1, wherein
the chemical composition contains one or more selected from the group consisting of:
Cu: 0.01 to 0.30%, and
Ni: 0.01 to 0.30%.

### Claim 3 (depends on 1)

The rail vehicle axle according to claim 1, wherein
the chemical composition contains one or more selected from the group consisting of:
Al: 0.005 to 0.100%, and
V: 0.005 to 0.060%.

### Claim 4 (depends on 2)

The rail vehicle axle according to claim 2, wherein
the chemical composition contains one or more selected from the group consisting of:
Al: 0.005 to 0.100%, and
V: 0.005 to 0.060%.