| 摘要 |
PURPOSE:To manufacture the titled steel independently of components contained with a conventional equipment for manufacturing a steel bar by hot rolling a steel contg. a prescribed amount of C, forcing the steel to be cooled under specified conditions, allowing it to cool, and carrying out finish rolling by a specified extent of stretch. CONSTITUTION:A steel contg. >=0.30wt% C is heated, hot rolled and forced to be cooled for 1-10sec. This cooling is stopped before a supercooled structure is produced, and the steel is allowed to cool to obtain a steel having a uniform ferrite-pearlite structure. The steel is then subjected to finish rolling by 0.5-5% extent of stretch. By this method, a high yield ratio suitable for the manufacture of a PC steel bar, a high strength bolt or the like as well as high strength and toughness can be provided to a bar steel or an unrefined steel.
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