HIGH STRENGTH LOW CARBON HOT-ROLLED STEEL SHEET WITH EXCELLENT HALL EXPANSIBILITY AND METHOD OF MANUFACTURING THE LOW CARBON HOT-ROLLED STEEL

摘要

PURPOSE: A low-carbon high-strength hot rolled steel plate with superior hole expandability and a manufacturing method thereof are provided to secure a steel plate with excellent strength and hole expandability through control of a hot-rolling process without cold rolling-annealing processes. CONSTITUTION: A method for manufacturing a low-carbon high-strength hot rolled steel plate comprises the steps of: hot-rolling slab to a finish rolling temperature of 850100C(S110), cooling the rolled plate to a martensite temperature range at a cooling rate of 100-250C/sec(S120), and coiling the cooled plate(S130). The slab comprises carbon of 0.03-0.08 weight%, silicon of 0.001-0.5 weight%, manganese of 1.3-1.8 weight%, aluminum of 0.001-0.1 weight%, two or more among vanadium of 0.06-0.15 weight%, molybdenum of 0.1-0.5 weight%, and chrome of 0.1-0.5 weight%, and iron and inevitable impurities of the remaining amount.