Jfe Steel Corporation

Ryo Matsuoka

Hideki Takahashi

Yoshikazu Yoshida

Yuzuru Kataoka

Rinya Kojo

Tomoo Horita

Tatsumi Kimura

Makoto Nakaseko

Mineyasu Takemasa

Hiroyuki Fukuda

Minoru Honjo

Yuta Tamura

Shigeo Okamoto

Naoki Iizuka

Proposed are the welding conditions under which welds are always stably formed such that the difference in hardness between flash-butt welds and rail base metal and the deflection in a bending test are in better ranges. A plurality of pieces of rail base metal are joined via welds formed by flash-butt welding, where the rail base metal has a chemical composition containing C: 0.60 to 1.20 mass %, Si: 0.10 to 1.50 mass %, Mn: 0.10 to 1.50 mass %, and Cr: 0.10 to 1.50 mass %, with the balance being Fe and inevitable impurities, and the flash-butt welding is performed with an amount of welding heat input of 1.50×10kA×sec or more and 4.50×10kA×sec or less.

Method for manufacturing rail, and rail

A rail cooling device configured to forcibly cool a rail by jetting a coolant includes a porous plate nozzle including a plurality of nozzle holes configured to jet the coolant to an underside of the base of the rail to cool the underside of the base of the rail. Ends in a width direction of the porous plate nozzle correspond to ends of the underside of the base of the rail. Nozzle holes of the porous plate nozzle at the ends of the width direction are smaller than nozzle holes of the porous plate nozzle at a central part in the width direction, and a maximum value of a distance between centers of the nozzle holes at both ends in the width direction is 30% or more of a width of the underside of the base.

Rail cooling device

A rail cooling method for forcibly cooling a rail by jetting a coolant includes jetting the coolant to a foot back part of the rail from a porous plate nozzle in which a nozzle hole at an end in a width direction is smaller than a nozzle hole at a central part in the width direction and causes a cooling capacity for the end in the width direction of the underside of the base of the rail to be lower than a cooling capacity for the central part in the width direction of the underside of the base of the rail.

Rail cooling method and rail cooling device

A rail heat treatment device includes a cooling header, an oscillation mechanism, and a control system including: a storage unit that stores therein at least information required for a oscillation control; and a control unit that obtains a permissible range of required cooling time for a rail that satisfies a permissible range of hardness of the rail based on a correlation expression representing a correlation between the cooling time for the rail with the cooling header and the hardness of the rail after cooling, controls a stroke and a speed of relative reciprocation of the rail and the cooling header based on the permissible range of the required cooling time, and causes the oscillation mechanism to perform the relative reciprocation of the rail and the cooling header by the stroke and at the speed.

Rail heat treatment device and rail heat treatment method

A rail cooling method includes: calculating, based on a relation between temperatures and an amount of warp of the rail cooled to ambient temperature after the forced cooling, the temperatures including a cooling start temperature of the head, a cooling end temperature of the head, a cooling start temperature of the foot and a cooling end temperature of the foot, a target value or a target value range for each of the temperatures so that the amount of warp of the rail at ambient temperature falls within a permissive range; and setting a cooling condition in accordance with the target value or the target value range to perform the forced cooling on the head and the foot.

Rail cooling method

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Tokyo, Japan

Ryo Matsuoka