Jfe Steel Corporation

Moriyasu Yamaguchi

Kenji Okushiro

Hiroyuki Fukuda

Hideo Kijima

Shigeru Endo

Tatsumi Kimura

Kiyoshi Uwai

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

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 pearlitic rail includes a composition including in % by mass: 0.70% to 0.90% of C; 0.1% to 1.5% of Si; 0.01% to 1.5% of Mn; 0.001% to 0.035% of P; 0.0005% to 0.030% of S; 0.1% to 2.0% of Cr, remainder of the composition consisting of Fe and inevitable impurities. Surface hardness of a rail top is not less than HB 430, and hardness at a depth of 25 mm from a surface of the rail top is not less than HB 410.

Pearlitic rail and method for manufacturing pearlitic rail

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

Moriyasu Yamaguchi