Abstract: A hot rolling line and a hot rolling method capable of finer refining crystal grains are provided. Specifically, the hot rolling line for a metal sheet is composed of a finish rolling mill, a leveler, and a cooling apparatus installed from upstream to downstream in this sequence in a metal sheet transporting direction. The hot rolling method is such that, in the above hot rolling line, a metal sheet obtained by finish rolling a metal piece is subjected to repeated bending processing by the leveler and then cooled.

Abstract: The present invention has an object to provide a manufacturing method of a long large-diameter composite cemented carbide roll and a hot rolling method of steel using the same. The roll manufacturing method covers a composite cemented carbide roll formed by engaging with, and fixing to, a steel arbor, a sleeve comprising an outer layer made of a cemented carbide formed by integrating a plurality of previously sintered cylindrical formed members and an inner layer made of a steel material formed on the inner surface of the outer layer. The sleeve has a sectional area ratio So/Si of the sectional area So of the outer layer and the sectional area Si of the inner layer in a cross-section perpendicular to the rotation axis within a range of from 0.3 to 20. The sleeve has a length within a range of from 520 to 6,000 mm. When hot-rolling steel, the cemented carbide rolls of the invention are used as work rolls of at least one stand for a roughing mill and/or a finishing mill.

Abstract: In a six high rolling mill comprising each pair of upper and lower work rolls, intermediate rolls and backup rolls, at least the intermediate rolls of the work and intermediate rolls being adapted for shifting in axial directions thereof, each of the intermediate rolls has a barrel length longer than that of the backup roll such that barrel ends of the intermediate roll extend beyond barrel ends of the-backup roll at maximum and minimum shifted positions of the intermediate roll, thereby providing a six high rolling mill having a high mill rigidity.