METHOD OF MANUFACTURING STRUCTURAL STEEL

摘要

PURPOSE: A method for manufacturing structural steel is provided to improve the surface scale property of a steel new structure (SN) type thick hot-rolled steel sheet for an earthquake-proof building structure. CONSTITUTION: A method for manufacturing structural steel includes: a step (S110) of extracting heated slab at a temperature of 1100 to 1180°C; a step (S120) of roughly rolling the extracted slab at a rough rolling finish temperature of 900 to 1000°C; a step (S130) of finish-rolling the roughly rolled steel in a condition in which a difference between a start temperature for finish-rolling and a finish temperature for finish-rolling is below 100°C; and a step (S140) of forcibly cooling the finish-rolled steel. In the step of finish-rolling the steel, the difference between the start temperature and the finish temperature is capable of being below 50°C. [Reference numerals] (AA) Start; (BB) End; (S110) Extract a slab (below 1180°C); (S120) Roughly rolling the extracted slab (AKANFL: below 1000°C); (S130) Finish-rolling (FET-FDT: below 100°C); (S140) Cooling