| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a structural steel material excellent in mechanical property even without performing quenching-tempering, and excellent in surface quality. SOLUTION: The structural steel material has cross sectional round shape of 120-180mm diameter and containing 0.35-0.50 mass% C formed from a steel ingot through heating, rough-rolling, hot-scarfing and finish-rolling processes. The method for manufacturing the structural steel material, is performed following processes: the steel ingot is heated at heating temperatures of 1,100-1,150°C; successively, the heating temperature is once lowered to 850-900°C and again raised to 950-1,020°C; after holding the steel ingot in this temperature, this steel ingot is discharged from the heating furnace and the rough-rolling is performed; and the ingot surface is scarfed with pre-ignited hot-scarfer at the surface temperature of 900-950°C; and successively, the finish-rolling is performed at rolling-finish temperatures of 750-850°C. COPYRIGHT: (C)2007,JPO&INPIT
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