High strength thin steel sheet for the superior press formability and surface quality and galvanized steel sheet and method for manufacturing the same

A method of manufacturing a high strength thin steel sheet for superior press formability, the method comprising:

• hot-working a steel slab, which comprises, by weight percent, 0.06 to 0.4% C, 1.0 to 5.0% Mn, 0.05 to 2.5% Si, 0.01 to 2.0% Ni, 0.02 to 2% Cu, 0.01 to 0.04% Ti, 0.05 to 2.5% Al, 0.005 to 0.1% Sb, 0.0005 to 0.004% B, 0.007% or less N, and balance Fe and inevitable impurities, and which meets relation of Ni+0.5×Mn+0.3×Cu≧0.9, which is defined as Ni*, and Al/Ni*≦1.3 at a same time, and relation of Ti≧0.028×Al, at a temperature above Ar3;
• hot-rolling winding the hot-wrought steel slab at a temperature between 500° C. and 700° C.;
• pickling and cold rolling the wound steel slab;
• annealing the cold-rolled steel slab at a temperature at which a fraction of austenite has at least 30%;
• and
• quenching the annealed steel slab from a temperature direct above a martensite forming temperature to a temperature below a bainite forming temperature, and cooling the quenched steel slab after at least 30 seconds.