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|1. (WO2018076965) COLD-ROLLED HIGH-STRENGTH STEEL HAVING TENSILE STRENGTH OF NOT LESS THAN 1500 MPA AND EXCELLENT FORMABILITY, AND MANUFACTURING METHOD THEREFOR|
|Applicants:||BAOSHAN IRON & STEEL CO., LTD.
|Title:||COLD-ROLLED HIGH-STRENGTH STEEL HAVING TENSILE STRENGTH OF NOT LESS THAN 1500 MPA AND EXCELLENT FORMABILITY, AND MANUFACTURING METHOD THEREFOR|
Provided is a cold-rolled high-strength steel having a tensile strength of not less than 1500 MPa and an excellent formability, the chemical elements thereof having the following mass percent ratios: 0.25% - 0.40% of C, 1.50% - 2.50% of Si, 2.0% - 3.0% of Mn, 0.03% - 0.06% of Al, P ≤ 0.02%, S ≤ 0.01%, N ≤ 0.01% and at least one of 0.1% - 1.0% of Cr and 0.1% - 0.5% of Mo, with the balance being Fe and other unavoidable impurities. The microstructure of the cold-rolled high-strength steel has 5% - 20% of residual austenite and 70% - 90% of martensite, and the carbon concentration ratio of the residual austenite to the martensite is greater than 3.5 and less than 15. A cold-rolled high-strength steel sheet has a high strength and an excellent formability through a rational ingredient design and microstructure control.