| 摘要 |
<p>The present invention provides a high tensile cold-rolled steel sheet having superior ductility, strain age-hardening characteristics, and crash resistance properties, and also provides a manufacturing method therefor. As a particular means, a thin cold-rolled steel sheet containing 0.05% to 0.30% of C, 0.4% to 2.0% of Si, 0.7% to 3.0% of Mn, 0.08% or less of P, 0.02% or less of Al, and 0.0050% to 0.0250% of N on a mass% basis is manufactured in which N/Al is 0.3 or more. This thin cold-rolled steel sheet is heated to a temperature between (an Ac1 transformation point) and (an Ac3 transformation point + 50 DEG C), is cooled at a cooling rate of 5 to 150 DEG C/second in the range of at least 600 to 500 DEG C, and is held in the temperature range of 350 to 500 DEG C. This steel sheet has superior ductility, strain age-hardening characteristics having a DELTA TS of 50 MPa or more, and crash resistance properties.</p> |
