| 摘要 |
<p>A high strength cold-rolled steel plate which has a chemical composition in mass%: C: 0.04 to 0.10%, Si: 0.5 to 1.5%, Mn: 1.8 to 3%, P: 0.02% or less, S: 0.01% or less, Sol.Al: 0.01 to 0.1%, N: 0.005% or less, and the balance: Fe and inevitable impurities, and has a metal structure consisting substantially of a ferrite phase and a martensite phase. The high strength cold-rolled steel plate exhibits good ductility of an elongation of 18% or more and excellent stretch-flanging property of a bore expanding percentage of 60% or more, in combination with a tensile strength of 780 MPa or more, and thus can be suitably used for a structural member of an automobile.</p> |
