Cold-rolled steel sheet having excellent corrosion resistance and formability, and method for manufacturing same

A method of manufacturing a cold rolled steel sheet, comprising:

• reheating a slab at a temperature of 1200° C. or higher, the slab including, by wt %, 0.01% or less (excluding 0%) of carbon (C), 0.5% or less (excluding 0%) of silicon (Si), 0.1 to 0.5% (excluding 0%) of manganese (Mn), 0.1% or less (excluding 0%) of aluminum (Al), 0.01% or less of phosphorus (P), 0.01% or less of sulfur (S), 0.005% or less of nitrogen (N) and 0.2 to 0.8% of niobium (Nb),
• the slab comprising one or more of 0.5% or less of antimony (Sb), 3.0% or less of chromium (Cr), 1.0% or less of molybdenum (Mo) and 0.5% or less of tungsten (W), comprising a remainder of iron (Fe) and inevitable impurities, and satisfying the following relational expression 1:
• 0.2≤[Sb]/0.5+[Cr]/3.0+[Mo]/1.0+[W]/0.5≤1.5, where [Sb], [Cr], [Mo] and [W] are the amounts (wt %) of relevant elements, respectively;
• finish rolling the reheated slab at a temperature of Ar3° C. or higher to obtain a hot-rolled steel sheet;
• coiling the hot-rolled steel sheet at a temperature ranging from 550 to 750° C.;
• cold rolling the coiled hot-rolled steel sheet at a reduction ratio of 50 to 95% to obtain a cold-rolled steel sheet;
• and
• continuously annealing the cold-rolled steel sheet at a temperature ranging from 600 to 900° C.