Granted Patent B2

US 12,221,660 · App. 17/593,298 · Granted Feb 11, 2025

Inventors: Minoru Honjo (Tokyo, JP); Mineyasu Takemasa (Tokyo, JP)

Assignee: JFE STEEL CORPORATION

C21D1/02C21D6/004C21D6/005C21D6/008C22C38/002C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C22C38/16C22C38/54

Abstract

Claims (26)

1. A method for producing a rail, the method comprising

subjecting a bloom to hot rolling to obtain a rail, wherein the bloom comprises a chemical composition containing, in mass %,

C: 0.60% or more and 0.85% or less,

Si: 0.10% or more and 1.00% or less, and

Mn: 0.10% or more and 1.30% or less,

with the balance being Fe and inevitable impurities,

subjecting the rail to accelerated cooling under a set of conditions wherein

a cooling start temperature of rail head, expressed as T1, is 750° C. or higher and 850° C. or lower,

a cooling stop temperature of rail head, expressed as T2, is higher than 700° C., and

T1-T2 is 20° C. or more, and

then allowing the rail to be naturally cooled,

wherein an average cooling rate of the surface temperature of the rail head during the accelerated cooling is 1.0° C./s or higher and 10° C./s or lower, and

an average cooling rate of the surface temperature of the rail head during the natural cooling is 0.2° C./s or higher and 0.6° C./s or lower.

2. The method of producing a rail according to claim 1 , wherein the chemical composition further contains, in mass %, at least one selected from the group consisting of

Cr: 1.50% or less,

V: 0.50% or less,

Cu: 0.50% or less,

Ni: 0.50% or less,

Nb: 0.10% or less,

Mo: 0.50% or less,

Al: 0.05% or less,

W: 0.50% or less,

B: 0.005% or less,

Ti: 0.05% or less,

Mg: 0.020% or less, and

Ca: 0.020% or less.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (23)