	US 12,264,373 B2
	Rail and method of manufacturing rail
Masaharu Ueda, Tokyo (JP); Jun Takahashi, Tokyo (JP); Teruhisa Miyazaki, Tokyo (JP); and Takuya Tanahashi, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/271,266
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Aug. 21, 2019, PCT No. PCT/JP2019/032627 § 371(c)(1), (2) Date Feb. 25, 2021, PCT Pub. No. WO2020/054339, PCT Pub. Date Mar. 19, 2020.
Claims priority of application No. 2018-168799 (JP), filed on Sep. 10, 2018.
Prior Publication US 2021/0395847 A1, Dec. 23, 2021
Int. Cl. C21D 6/00 (2006.01); B21B 1/085 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/24 (2006.01); C22C 38/34 (2006.01); C22C 38/38 (2006.01); E01B 5/02 (2006.01)

CPC C21D 6/008 (2013.01) [B21B 1/085 (2013.01); C21D 8/0226 (2013.01); C22C 38/001 (2013.01); C22C 38/02 (2013.01); C22C 38/24 (2013.01); C22C 38/34 (2013.01); C22C 38/38 (2013.01); E01B 5/02 (2013.01)]

4 Claims

1. A rail comprising, by mass %:

C: 0.75% to 1.20%;

Si: 0.10% to 2.00%;

Mn: 0.10% to 2.00%;

Cr: 0.10% to 1.20%;

V: 0.010% to 0.200%;

N: 0.0030% to 0.0200%;

P≤0.0250%;

S≤0.0250%;

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%;

Nb: 0% to 0.0500%;

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%;

Al: 0% to 1.00%; and

a remainder including Fe and impurities, wherein

a structure ranging from an outer surface of a head portion as an origin to a depth of 25 mm includes 95% or greater of a pearlite structure by area ratio,

a hardness of the structure is in a range of Hv 360 to 500, and

in ferrite of the pearlite structure at a position at the depth of 25 mm from the outer surface of the head portion as the origin, a number density of a V nitride having a grain size of 0.5 to 4.0 nm and including Cr is in a range of 1.0×10¹⁷to 5.0×10¹⁷cm⁻³.