Abstract: A method for manufacturing a high-strength cold-rolled steel sheet according to an embodiment includes the steps of: reheating a steel slab, which includes 0.10 wt % to 0.13 wt % carbon (C), 0.9 wt % to 1.1 wt % silicon (Si), 2.2 wt % to 2.3 wt % manganese (Mn), 0.35 wt % to 0.45 wt % chromium (Cr), 0.04 wt % to 0.07 wt % molybdenum (Mo), 0.02 wt % to 0.05 wt % antimony (Sb), and the remainder being iron (Fe) and inevitable impurities, at a temperature of 1150° C. to 1250° C.; hot-rolling the reheated slab in such a manner as to reach a finishing mill delivery temperature of 800° C. to 900° C.; cooling the hot-rolled slab to a temperature of 600° C. to 700° C. and coiling the cooled slab, thereby obtaining a hot-rolled steel sheet; pickling the hot-rolled steel sheet, followed by cold rolling; annealing the cold-rolled steel sheet in a two-phase region of ? and ? phases; and cooling the annealed steel sheet to the martensite temperature range, followed by overaging.

Abstract: A method for manufacturing a high-strength cold-rolled steel sheet according to an embodiment includes the steps of: reheating a steel slab, which includes 0.10 wt % to 0.13 wt % carbon (C), 0.9 wt % to 1.1 wt % silicon (Si), 2.2 wt % to 2.3 wt % manganese (Mn), 0.35 wt % to 0.45 wt % chromium (Cr), 0.04 wt % to 0.07 wt % molybdenum (Mo), 0.02 wt % to 0.05 wt % antimony (Sb), and the remainder being iron (Fe) and inevitable impurities, at a temperature of 1150° C. to 1250° C.; hot-rolling the reheated slab in such a manner as to reach a finishing mill delivery temperature of 800° C. to 900° C.; cooling the hot-rolled slab to a temperature of 600° C. to 700° C. and coiling the cooled slab, thereby obtaining a hot-rolled steel sheet; pickling the hot-rolled steel sheet, followed by cold rolling; annealing the cold-rolled steel sheet in a two-phase region of ? and ? phases; and cooling the annealed steel sheet to the martensite temperature range, followed by overaging.

Abstract: A high-strength steel sheet according to the present invention comprises, by weight, 10.0-15.0% Mn, 6.0-9.0% Al, 0.5-2.0% Cr, 0.8-1.6% C, and 0.001-0.01% N, and further comprises, by weight, 0.02-0.1% V, 0.005-0.015% Nb, and 0.005-0.02% Mo, or further comprises 0.1-0.5 wt % TiAl particles. The high-strength steel sheet has a mixed structure comprising austenite and a fine k-carbide having a mean particle diameter of 10-500 nm.

Abstract: A high-strength steel sheet according to the present invention comprises, by weight, 10.0-15.0% Mn, 6.0-9.0% Al, 0.5-2.0% Cr, 0.8-1.6% C, and 0.001-0.01% N, and further comprises, by weight, 0.02-0.1% V, 0.005-0.015% Nb, and 0.005-0.02% Mo, or further comprises 0.1-0.5 wt % TiAl particles. The high-strength steel sheet has a mixed structure comprising austenite and a fine k-carbide having a mean particle diameter of 10-500 nm.