METHOD FOR COOLING HOT ROLLED STEEL SHEET, DEVICE THEREFOR AND MANUFACTURE OF STEEL SHEET EXCELLENT IN BRITTLE FRACTURE PROPAGATION STOP CHARACTERISTICS

摘要

PROBLEM TO BE SOLVED: To form the outer layer of a steel sheet into fine structure by inclining the angle formed with the center line of cooling water spray nozzles and the normal line to transporting face toward side edges by a specified amount in every bisected cooling zone from the center line of the transporting face to the side edges. ;SOLUTION: Laminar flow nozzles 5 are provided on a laminar pipe 4 in the direction perpendicular to the slab transporting face 8 and, in a spray nozzle 7, inclined spray nozzle groupes 7-1 and 7-2 are provided in the bisected cooling zones from the center line L-L of the slab transporting face 8 toward the side edges E, F. The inclined spray nozzle groupes 7-1 and 7-2 are composed so as to have nozzle spray divergent angle in the range of 40-120° around the nozzle center line and inclined angle of the nozzle center line in the range of 2-22° toward the side edges E, F to the normal line to the slab transporting face 8. In this way, the steel sheet S after completing rough rolling is uniformly cooled, finish rolling is executed while heat is recuperated by the internal heat of the steel sheet and brittle fracture propagation stop characteristics are improved by the fine structure.;COPYRIGHT: (C)1997,JPO