| 摘要 |
PROBLEM TO BE SOLVED: To improve the toughness and ductility of a rail by subjecting the outermost surface of the head of the rail to accelerated cooling at a temp. equal to or above the specified one at a cooling rate in a specified range before any one pass in finish rolling. SOLUTION: The outermost surface of the head of a rail is subjected to accelerated cooling at >=20 deg.C at a cooling rate of 5 to 100 deg.C/sec. In the case the temp. of the head of the rail before finish rolling is reduced, the recrystallized grains are made fine. Preferably, the finish rolling is executed in such a manner that the reduction of cross-sectional area in the head of the rail is controlled to >=5%, after the completion of the finish rolling, successively, or after reheating successively to temporary cooling, the head of the rail is subjected to accelerated cooling at 700 to 500 deg.C at 1 to 5 deg.C/sec. The slab preferably has a compsn. contg. one or more kinds among, by weight, 0.55 to 1.20% C, 0.10 to 1.20% Si, 0.10 to 1.50% Mn and 0.002 to 0.050% S, furthermore contg. one or more kinds among 0.0005 to 0.05% Al, 0.001 to 0.05% Nb, 0.1 to 4.0% Ni and 0.1 to 4.0% Cu and one or more kinds among 0.1 to 1.0% Cr, 0.01 to 0.50% Mo, 0.01 to 1.00% V and 0.0001 to 0.0050% B as well.
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