Rail

Patent metadata

Field	Value
Publication number	US-12247358-B2
Application number	US-202017432607-A
Country	US
Kind code	B2
Filing date	Mar 2, 2020
Priority date	Mar 15, 2019
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

A rail including a predetermined chemical composition is provided, in which 90 area % or greater of a metallographic structure in a cross section of a rail web portion is a pearlite structure, a minimum value of a hardness in the cross section of the rail web portion is Hv 300 or greater, and a difference between a maximum value and the minimum value of the hardness in the cross section of the rail web portion is Hv 40 or less.

First claim

The invention claimed is:

1. A rail comprising steel composition including, by mass %:
C: 0.75 to 1.20%;
Si: 0.10 to 2.00%;
Mn: 0.10 to 2.00%;
Cr: 0 to 2.00%;
Mo: 0 to 0.50%;
Co: 0 to 1.00%;
B: 0 to 0.0050%;
Cu: 0 to 1.00%;
Ni: 0 to 1.00%;
V: 0 to 0.50%;
Nb: 0 to 0.050%;
Ti: 0 to 0.0500%;
Mg: 0 to 0.0200%;
Ca: 0 to 0.0200%;
REM: 0 to 0.0500%;
Zr: 0 to 0.0200%;
N: 0 to 0.0200%;
Al: 0 to 1.00%;
P: 0.0250% or less;
S: 0.0250% or less; and
a remainder including Fe and impurities,
wherein 90 area % or greater of a metallographic structure in a cross section of a rail web portion is a pearlite structure,
a minimum value of a hardness in the cross section of the rail web portion is Hv 300 or greater, and
a difference between a maximum value and the minimum value of the hardness in the cross section of the rail web portion is Hv 40 or less.

2. The rail according to claim 1 ,
wherein the difference between the maximum value and the minimum value of the hardness in the cross section of the rail web portion is Hv 20 or less.

3. The rail according to claim 2 ,
wherein the steel composition includes, by mass %, one or two or more selected from the group consisting of:
Cr: 0.01 to 2.00%;
Mo: 0.01 to 0.50%;
Co: 0.01 to 1.00%;
B: 0.0001 to 0.0050%;
Cu: 0.01 to 1.00%;
Ni: 0.01 to 1.00%;
V: 0.005 to 0.50%;
Nb: 0.0010 to 0.050%;
Ti: 0.0030 to 0.0500%;
Mg: 0.0005 to 0.0200%;
Ca: 0.0005 to 0.0200%;
REM: 0.0005 to 0.0500%;
Zr: 0.0001 to 0.0200%;
N: 0.0060 to 0.0200%; and
Al: 0.0100 to 1.00%.

4. The rail according to claim 1 ,
wherein the steel composition includes, by mass %, one or two or more selected from the group consisting of:
Cr: 0.01 to 2.00%;
Mo: 0.01 to 0.50%;
Co: 0.01 to 1.00%;
B: 0.0001 to 0.0050%;
Cu: 0.01 to 1.00%;
Ni: 0.01 to 1.00%;
V: 0.005 to 0.50%;
Nb: 0.0010 to 0.050%;
Ti: 0.0030 to 0.0500%;
Mg: 0.0005 to 0.0200%;
Ca: 0.0005 to 0.0200%;
REM: 0.0005 to 0.0500%;
Zr: 0.0001 to 0.0200%;
N: 0.0060 to 0.0200%; and
Al: 0.0100 to 1.00%.

5. The rail according to claim 1 , wherein
the rail includes a rail head portion, a rail foot portion, and the raid web portion extending between the rail head portion and the rail foot portion, and
the web portion has a cross-sectional hardness distribution within a range of 0 to 40 Hv, the cross-sectional hardness distribution being a distribution of a hardness at a cross section in a thickness direction of the rail web portion that is perpendicular to a direction in which the web portion extends.

Assignees

• Nippon Steel Corp

Inventors

• Ueda Masaharu
• Miyazaki Teruhisa
• Tanahashi Takuya
• Maeda Yusuke

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C22C38/18

  containing chromium · CPC title

• C22C38/16

  containing copper · CPC title

• C22C38/14

  containing titanium or zirconium · CPC title

• C22C38/12

  containing tungsten, tantalum, molybdenum, vanadium, or niobium · CPC title