Production manner null of the hot rolling steel sheet which is superior in scale

摘要

PURPOSE:To produce a hot rolled steel plate excellent in adhesive strength of scale by connecting, while decoiling a coiled sheet bar of steel with specific composition, the head end of this sheet bar to the tail end of a preceding sheet bar, exerting hot finish rolling while applying tension under specific conditions, applying strain, and then coiling the resulting hot rolled steel plate. CONSTITUTION:A steel having a composition consisting of, by weight, 0.001-0.20% C, =0.50% Si, 0.05-2.00% Mn, =0.03% P, =0.01% S, 0.01-0.10% solAl, =0.020% N, and the balance Fe with inevitable impurities is heated up to a temp. not lower than the Ac, point and roughened into a sheet bar, which is temporarily coiled. While being decoiled, the head end of this coil is connected to the tail end of a preceding sheet bar. Then, while applying a tension of 1-4kgf/mm2, hot finish rolling is continuously performed. A tensile strain of 0.1-1% is applied in the course between the completion of rolling and coiling and coiling is done at 550-700 deg.C. By this method, the formation of bubbles in the scale on the steel surface can be effectively prevented and the dense scale can be formed and, as a result, the hot rolled steel plate excellent in adhesive strength of scale can be obtained.