Jfe Steel Corporation

Kenji Okushiro

Hideo Kijima

Hiroyuki Fukuda

Moriyasu Yamaguchi

Hiroshi Ishikawa

Kazuya Tokunaga

A rail comprises a predetermined chemical composition. In a hardness distribution in a region from a rail head surface to a depth of 16.0 mm, a part having higher hardness than V1 that is minimum hardness in a first internal region is present in a second internal region, and hardness of the rail head surface is HBW 400 to 520 and average hardness in the region from the rail head surface to the depth of 16.0 mm is HBW 350 or more.

Rail and manufacturing method therefor

There are provided an apparatus for cooling a rail and a method for manufacturing a rail, capable of inexpensively manufacturing a rail with high hardness and high toughness. The apparatus for cooling a rail, configured to jet a cooling medium to the head portion and foot portion of a rail in an austenite temperature range to forcibly cool the rail, includes: a first cooling unit including plural first cooling headers configured to jet the cooling medium as gas to the head top face and head side of the head portion, and first driving units configured to move at least one first cooling header of the plural first cooling headers to change the jet distance of the cooling medium jetted from the first cooling header; and a second cooling unit including a second cooling header configured to jet the cooling medium as gas to the foot portion.

Cooling device and production method for rail

Rail-manufacturing equipment that performs forced cooling on at least a head of a hot rail hot-rolled at or heated to the austenite region temperature or higher. The rail-manufacturing equipment includes a head-cooling header configured to jet a cooling medium toward the head of the rail, a head thermometer configured to measure surface temperature of the head of the rail, and a controller configured to adjust jet of the cooling medium from the head-cooling header. The controller includes a temperature-monitoring unit configured to monitor measurement results by the head thermometer during the forced cooling, and a cooling-rate controller.

Rail manufacturing method and manufacturing equipment

A manufacturing method and a manufacturing apparatus for a head hardened rail to which various alloy elements are added and which is excellent in hardness and toughness of a head portion surface layer. The method includes, when forcibly cooling at least a head portion of a hot-rolled rail or a heated rail, starting the forcible cooling from a state where a surface temperature of the head portion of the rail is not less than an austenite range temperature, and performing the forcible cooling at a cooling rate of 10&#xb0; C./sec or more until the surface temperature reaches 500&#xb0; C. or more and 700&#xb0; C. or less after the forcible cooling is started.

Head hardened rail manufacturing method and manufacturing apparatus

Rail manufacturing method performs, on at least a head of the rail that is hot after hot-rolled at an austenite region temperature or higher or after heated to the austenite region temperature or higher, forced cooling: for 10 seconds from start of the forced cooling so that a cooling rate at a surface of the head becomes 1&#xb0; C./s to 20&#xb0; C./s; during a period after a lapse of 10 seconds from the start until heat generation during transformation begins at the surface so that the cooling rate becomes 1&#xb0; C./s to 5&#xb0; C./s; during transformation from beginning to end of the heat generation during transformation so that the cooling rate becomes lower than 1&#xb0; C./s or a temperature-rising rate becomes 5&#xb0; C./s or lower; and during a period after the end of the heat generation during transformation until temperature at the surface becomes 450&#xb0; C. or lower so that the cooling rate becomes 1&#xb0; C./s to 20&#xb0; C./s.

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Tokyo, Japan

Kenji Okushiro