Rail

Patent metadata

Field	Value
Publication number	US-2019161839-A1
Application number	US-201716098987-A
Country	US
Kind code	A1
Filing date	May 19, 2017
Priority date	May 19, 2016
Publication date	May 30, 2019
Grant date	—

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.

First claim

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%; Pb: 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 V: 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, 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.

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 1 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 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%.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Ueda Masaharu
• Miyazaki Teruhisa

Classifications

• C22C38/04

  containing manganese · CPC title

• C22C38/02

  containing silicon · CPC title

• C21C5/5264

  Manufacture of alloyed steels including ferro-alloys · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C22C38/60 Primary

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title