US 2026/0242910 A1Published application

Rail and method of producing same

AssigneeJfe Steel Corporation

InventorsKeisuke ANDO, Hirofumi OHTSUBO, Minoru HONJO

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Abstract

A rail with excellent fatigue crack propagation resistance at the rail base underside is provided. The rail includes a chemical composition containing C: 0.70 mass % to 1.20 mass %, Si: 0.10 mass % to 1.20 mass %, Mn: 0.10 mass % to 1.50 mass %, P: 0.035 mass % or less, S: 0.020 mass % or less, and Cr: 0.05 mass % to 2.00 mass %, with a balance consisting of Fe and inevitable impurities. An area ratio of a pearlitic microstructure at a depth of 1 mm from a surface of a central portion of a rail base underside is 95% or more, and a value of HC expressed by Expression (1) satisfies Expression (2), HC={(12×[% C])+([% Si]/10)+([% Mn]/20)+([% Cr]/18)}2 (1) HC≤(120×GS)/(1.1×BS) (2).

Claims4

Dependent claims

A rail comprising:

a chemical composition containing
C:
0.70 mass % to 1.20 mass %,
Si:
0.10 mass % to 1.20 mass %,
Mn:
0.10 mass % to 1.50 mass %,
P:
0.035 mass % or less,
S:
0.020 mass % or less, and
Cr:
0.05 mass % to 2.00 mass %,
with a balance consisting of Fe and inevitable impurities,
wherein an area ratio of a pearlitic microstructure at a depth of 1 mm from a surface of a central portion of a rail base underside is 95.0% or more, and
a value of HC expressed by Expression (1) satisfies Expression (2),
HC
=
{
(
12
×
[
%
⁢
C
]
)
+
(
[
%
⁢
Si
]
/
10
)
+
(
[
%
⁢
Mn
]
/
20
)
+
(
[
%
⁢
Cr
]
/
18
)
}
2
(
1
)
HC
≤
(
120
×
GS
)
/
(
1.1
×
BS
)
(
2
)
where
[% C], [% Si], [% Mn], and [% Cr] are respective contents by mass % of C, Si, Mn, and Cr,
GS is the prior austenite grain size in μm at the central portion of the rail base underside, and
BS is the pearlite block size in μm at the central portion of the rail base underside.

80 more elements

Dependencies are inferred from the claim text.

Facts

Application: 19/159,830Filed 16 Jan 2024
Priority: JP 2023-04905624 Mar 2023
Published: 20 Aug 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification31 codes

C22C 38/32
Containing chromium: with boron
C21D 1/02
General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering: hardening articles or materials formed by…
C21D 1/84
General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering: controlled slow cooling
C21D 6/002
Heat treatment of ferrous alloys: containing Cr

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