| 摘要 |
<p>The present invention relates to a cold-rolled steel sheet and a manufacturing method thereof and, more specifically, relates to a high-strength cold-rolled steel sheet in a 150 kg class tensile strength and a manufacturing method thereof. The present invention provides a method to manufacture a cold-rolled steel sheet, which comprises the steps of: cold rolling a hot-rolled steel sheet consisting of 0.23-0.27 wt% of carbon (C), 0.1-0.2 wt% silicon (Si), 2.0-2.5 wt% of manganese (Mn), 0.02-0.04 wt% of aluminum (Al), 0.09-1.1 wt% of molybdenum (Mo), 0.04-0.07 wt% of niobium (Nb), 0.01-0.03 wt% of titanium (Ti), 0.002-0.003 wt% of boron (B), and a balance of iron (Fe) and inevitable impurities; annealing a cold-rolled steel sheet in an austenite single-phase reverse greater than or equal to Ac3 point by heating the cold-rolled steel sheet; cooling the annealing-treated steel sheet to a martensite temperature reverse less than or equal to Ms point; and tempering the cooled steel sheet in the martensite temperature reverse.</p> |
