HIGH STRENGTH COMPLEX PHASE COLD-ROLLED STEEL SHEET, GALVANIZED STEEL SHEET, GALVA-ANNEALED STEEL SHEET WITH EXCELLENT AGING RESISTANCE AND DENTING RESISTANCE AND MANUFACTURING METHOD THEREOF

摘要

Disclosed are a high strength complex phase cold-rolled steel sheet, a galvanized steel sheet, and a glava-annealed steel sheet with excellent aging resistance and denting resistance, and manufacturing methods thereof. According to the present invention, the method for manufacturing the high strength complex phase cold-rolled steel sheet comprises the steps of: (a) reheating a slav board consisting of 0.01-0.05 wt% of carbon (C), less than or equal to 0.03 wt% of silicon (Si), 1.0-2.0 wt% of manganese (Mn), less than or equal to 0.02 wt% of phosphorus (P), less than or equal to 0.005 wt% of sulfur (S), 0.3-1.2 wt% of chrome (Cr), 0.1-0.5 wt% of molybdenum (Mo), 0.4-1.2 wt% of aluminum (Al), and the rest of iron (Fe) and inevitable impurities, hot-rolling the same at the temperature of over Ar3, and winding the same at the temperature of over 650°C; (b) acid-cleaning the wound board and cold-rolling the same; (c) annealing the cold-rolled board and cooling the same at the temperature of under Ms; and (d) temper rolling the cooled board.;COPYRIGHT KIPO 2015