HIGH STRENGTH COLD-ROLLED DUAL PHASE STEEL SHEET FOR AUTOMOBILE WITH EXCELLENT FORMABILITY AND METHOD OF MANUFACTURING THE COLD-ROLLED MULTI PHASE STEEL SHEET

摘要

PURPOSE: A high strength cold-rolled multi-phase steel sheet with superior moldability for a vehicle and a manufacturing method thereof are provided to enhance the press formability of a cold-rolled multi-phase steel sheet by securing an elongation ratio and increasing an average Rankford value. CONSTITUTION: A high strength cold-rolled multi-phase steel sheet comprises carbon of 0.01-0.08weight%, silicon of 0.5 weight% or less, manganese of 1.2-1.6weight%, phosphorus of 0.015-0.030weight%, one or more among aluminum of 0.30-0.70weight%, vanadium of 0.20-0.30weight%, chrome of 0.30-0.60weight%, molybdenum of 0.05-0.15weight%, and titanium of 0.01-0.02weight%, and iron and inevitable impurities of the remaining amount.