PURPOSE: Provided is a method for manufacturing a steel strip(50kg grade) with superior strength and yield ratio, which is suitable for weldable structural steels. CONSTITUTION: The method for manufacturing a steel sheet with superior strength and yield ration includes: injection of 0.6-1kg of Ca-Si into 1ton-molten liquid which comprises C 0.09-0.17%, Si 0.10-0.40%, Mn 1.00-1.60%, P 0.025% or less, S 0.010% or less, Nb 0.008-0.02%, Ti 0,008-0.02%, a balance of Fe and other unavoidable impurities in order to spheroidize MnS inclusions; continuous casting the spheroidized molten liquid into the shape of steel slab; finish rolling the steel slab at a temperature range of 800 to 900deg.C; cooling the rolled steel to a temperature range of 470 to 650deg.C at a cooling rate of 3 to 7deg.C/sec, starting from a temperature range of 850 to 750deg.C which is just higher than Ar3 transformation temperature point; and cooling to an ambient temperature.
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