IP Library Granted Patent US 10,995,396
Granted Patent B2
US 10,995,396 · App. 16/098,987 · Granted May 4, 2021

Rail

Inventors: Masaharu Ueda (Tokyo, JP); Teruhisa Miyazaki (Tokyo, JP)
Assignee: NIPPON STEEL CORPORATION
C22C38/60C21C5/5211C21C5/5264C21D9/04C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/10C22C38/12C22C38/14C22C38/16C22C38/18C21C2007/0012C21D2211/004C21D2211/009Y02P10/20
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Quick Facts
Patent No.
US 10,995,396
App. No.
16/098,987
Granted
May 4, 2021
Kind
B2
Abstract

A rail according to an aspect of the present invention is manufactured by melting steel using an electric furnace, satisfies a predetermined range as a chemical composition and particularly includes Pb: 0.0003% to 0.0020%, 95 area % or more of a region from an outer surface of a head portion to a depth of 20 mm is a pearlite structure, and a hardness in the region from the outer surface of the head portion to the depth of 20 mm is in a range of Hv 300 to Hv 500.

Claims (45)

1. A rail manufactured by melting steel using an electric furnace comprising, as a chemical composition, by unit mass %:

C: 0.75% to 1.20%;

Si: 0.10% to 2.00%;

Mn: 0.10% to 2.00%;

P≤0.0250%;

S≤0.0250%;

Ph: 0.0003% to 0.0020%;

a group a: one or two of Cr: 0% to 2.00% and Mo: 0% to 0.50%;

a group b: Co: 0% to 1.00%;

a group c: B: 0% to 0.0050%;

a group d: one or two of Cu: 0% to 1.00% and Ni: 0% to 1.00%;

a group e: one or two or more of \′: 0% to 0.50%, Nb: 0% to 0.0500%, and Ti: 0% to 0.0500%;

a group f: one or two or more of Mg: 0% to 0.0200%, Ca: 0% to 0.0200%, and REM: 0% to 0.0500%;

a group g: Zr: 0% to 0.0200%;

a group h: Al: 0% to 1.0000%;

a group i: N: 0% to 0.0200%; and

a remainder including Fe and impurities,

wherein 95 area % or more of a region from an outer surface of a head portion to a depth of 20 mm is a pearlite structure,

a hardness in the region from the outer surface of the head portion to the depth of 20 mm is in a range of dv 300 to 500,

an impact value is 10.0 J/cm 2 or more, and

the hardness in the region from the outer surface of the head portion to the depth of 20 mm is obtained by measuring the Vickers hardness at 10 or more points under a load of 98 N at each of the measurement position of a depth of 2 ram from the outer surface of the head portion and the measurement position of a depth of 20 mm from the outer surface of the head portion, and calculating the average value thereof.

2. The rail according to claim 1 ,

wherein an average number density of Pb oxide-based inclusions having a grain size of 1.0 μm to 5.0 μm is 100 pieces/1000 μm 2 or less, in a cross-section of the region from the outer surface of the head portion to the depth of 2 mm to 20 mm.

3. The rail according to claim 2 comprising, as the chemical composition, by unit mass %:

one group or two or more groups of,

a group a: one or two of Cr: 0.10% to 2.00% and Mo: 0.01% to 0.50%;

a group b: Co: 0.01% to 1.00%;

a group c: B: 0.0001% to 0.0050%;

a group d: one or two of Cu: 0.01% to 1.00% and Ni: 0.01% to 1.00%;

a group e: one or two or more of V: 0.01% to 0.50%, Nb: 0.0010% to 0.0500%, and Ti: 0.0030% to 0.0500%;

a group f: one or two or more of Mg: 0.0005% to 0.0200%, Ca: 0.0005% to 0.0200%, and REM: 0.0005% to 0.0500%;

a group g: Zr: 0.0001% to 0.0200%;

a group h: Al: 0.0050% to 1.0000%; and

a group i: N: 0.0050% to 0.0200%.

4. The rail according to claim 1 comprising, as the chemical composition, by unit mass %:

one group or two or more groups,

a group a: one or two of Cr: 0.10% to 2.00% and Mo: 0.01% to 0.50%;

a group b: Co: 0.01% to 1.00%;

a group c: B: 0.0001% to 0.0050%;

a group d: one or two of Cu: 0.01% to 1.00% and Ni: 0.01% to 1.00%;

a group e: one or two or more of V: 0.01% to 0.50%, Nb: 0.0010% to 0.0500%, and Ti: 0.0030% to 0.0500%;

a group f: one or two or more of Mg: 0.0005% to 0.0200%, Ca: 0.0005% to 0.0200%, and REM: 0,0005% to 0.0500%;

a group g: Zr: 0.0001% to 0.0200%;

a group h: Al: 0.0050% to 1.0000%; and

a group i: N: 0.0050% to 0.0200%.

Assignments (2)
CHANGE OF NAME Recorded May 14, 2019
From: NIPPON STEEL & SUMITOMO METAL CORPORATION
To: NIPPON STEEL CORPORATION
Reel/Frame 049257/0828 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Nov 5, 2018
From: UEDA, MASAHARU; MIYAZAKI, TERUHISA
To: NIPPON STEEL & SUMITOMO METAL CORPORATION
Reel/Frame 047413/0290 →