High-strength hot-dip galvanized steel sheet with high ductility and excellent formability, and manufacturing method for same

A method for manufacturing a hot-dip galvanized steel sheet having excellent ductility and formability, the method comprising:

• preparing a steel slab containing, by wt %, 0.06 to 0.16% of carbon (C), 0.8% or less (excluding 0%) of silicon (Si), 2.1 to 2.7% of manganese (Mn), 0.4% or less (excluding 0%) of molybdenum (Mo), 1% or less (excluding 0%) of chromium (Cr), 0.1% or less (excluding 0%) of phosphorus (P), 0.02% or less of sulfur(S), 1% or less (excluding 0%) of aluminum (sol.Al), 0.001 to 0.04% of titanium (Ti), 0.001 to 0.04% of niobium (Nb), 0.01% or less (excluding 0%) of nitrogen (N), 0.01% or less of boron (B), 0.05% or less of antimony (Sb), and a balance of Fe and unavoidable impurities, and satisfying the following Relational Expression 1,
• reheating the steel slab;
• hot rolling the reheated steel slab to manufacture a hot-rolled steel sheet, wherein a finish rolling end temperature is Ar3 to Ar3+50° C.;
• coiling the hot-rolled steel sheet at 400 to 650° C.;
• cooling the coiled hot-rolled steel sheet to room temperature at an average cooling rate of 0.1° C./s or lower;
• cold rolling the cooled hot-rolled steel sheet at a reduction ratio of 40 to 70% to manufacture a cold-rolled steel sheet;
• continuously annealing the cold-rolled steel sheet at a temperature of 820 to 860° C.;
• primarily cooling the continuously annealed steel sheet to a temperature within a range of 630 to 680° C. at an average cooling rate of 10° C./s or lower;
• secondarily cooling the primarily cooled steel sheet to a temperature of 300 to 350° C. at an average cooling rate of 5° C./s or higher using hydrogen gas;
• reheating the secondarily cooled steel sheet to a temperature of 400 to 480° C., and then maintaining the reheated steel sheet for 60 seconds or longer;
• and
• hot-dip galvanizing the maintained steel sheet at a temperature of 400 to 450° C. and then cooling the hot-dip galvanized steel sheet to a temperature of Ms to 100° C. or lower at an average cooling rate of 5° C./s or higher,
• (4×C+Si+Al)/(Mn+Cr+5×Mo+200×B)≤0.35. [Relational Expression 1]