PRODUCTION OF HOT-ROLLED STEEL STRIP HAVING NO SURFACE SCALE DEFECT

摘要

PURPOSE:To execute the effective hot rolling to prevent the formation of the red scale defect which arises particularly on the rear surface of a hot-rolled steel strip by transferring a sheet bar which is subjected to rough rolling while the formation of scale is suppressed or the scale is removed via table rollers in the state of natural cooling. CONSTITUTION:A slab (S45C, 215mmX1,125mmX9,500mm) having the component compsn. shown by, for example, a table-1 is charged into a heating furnace and is heated or 3.5hr at 1,160 deg.C. The heated slab is rolled to a sheet bar by a roughing mill provided with a descaler. The sheet bar is in succession thereto introduced into a finishing mill kept at 850 deg.C inlet temp. by which the hot-rolled steel strip sized at 5.7tX1,100mm is produced. The sheet bar after the rough rolling is held in the state of natural cooling during the transfer on the table roller and is subjected to finish rolling. The formation of red scale on both front and rear surfaces of the hot-rolled steel strip is not observed when a visual inspection is made after the end of the finish rolling.