| 摘要 |
<p>A cold rolled steel having excellent workability and strength, and the manufacturing method thereof are provided to promote the adaptation of a high-strength material for outer vehicle panels and to supply a steel sheet of stable quality by manufacturing a cold rolled steel at the 340MPa tensile strength level having uniform brake hardenability of 30MPa or more. A cold rolled steel having excellent workability and strength comprises 0.0015~0.0080 weight percent carbon(C), less than 0.8 weight percent silicon(Si), 0.1~0.8 weight percent manganese(Mn), 0.005~0.06 weight percent phosphorus(P), 0.004~0.015 weight percent sulfur(S), 0.03~0.1 weight percent aluminum(Al), less than 0.0050 weight percent nitrogen(N), and iron(Fe) and other inevitable impurities, wherein niobium(Nb) is added certainly within the range of 0.004~0.03 weight percent.</p> |
