Title:
HIGH-STRENGTH COLD ROLLED STEEL SHEET HAVING SUPERIOR DEEP DRAWABILITY AND A HIGH YIELD RATIO, GALVANIZED STEEL SHEET USING SAME, ALLOYED GALVANIZED STEEL SHEET, AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2010/074458
Kind Code:
A2
Abstract:
The present invention relates to a cold rolled steel sheet having a yield ratio of 60% or higher, superior dent resistance and durability, superior drawability having an r-value of 1.4 or higher, and a superior tensile strength of 490 MPa or higher, to a galvanized steel sheet using same, to an alloyed galvanized steel sheet, and to a method for manufacturing same. More particularly, the present invention relates to a high-strength cold rolled steel sheet having superior deep drawability and a high yield ratio, comprising, by weight, C: 0.02-0.05%, Mn: 1.0-3.0%, Si: 0.5-2.0%, P: 0.05% or less, N: 0.006% or less, Al: 0.01-0.1%, S: 0.012% or less, and Nb: 0.04-0.15%, and one or more components selected from a group consisting of Ti, B, and Zr, wherein said components satisfy the condition in which the following Eq_N value is 0.001 or less and the following Eq_C value is 0.03 or less. The residuals consist of Fe and inevitable impurities, and the fraction of the retained austenite is 5% or less. The present invention also relates to a galvanized steel sheet using same, to an alloyed galvanized steel sheet, and to a method for manufacturing same. Eq_N = N - 14 × (Ti/47.9 + Zr/91.2 + B/10.8) Eq_C = C - 12/92.9 × Nb Eq_C = C - 12 × (Nb/92.9 + (Ti - 47.9/14 ×N)/47.9+ (Zr - 91.2/14 × N)/91.2) (wherein, if Ti - 47.9/14 ×N < 0, Ti - 47.9/14 ×N is regarded as 0, and if Zr - 91.2/14 × N < 0, Zr - 91.2/14 × N is regarded as 0).
Inventors:
LEE KYOO-YOUNG (KR)
CHIN KWANG-GEUN (KR)
KIM JONG-SANG (KR)
HONG YOUNG-KWANG (KR)
CHIN KWANG-GEUN (KR)
KIM JONG-SANG (KR)
HONG YOUNG-KWANG (KR)
Application Number:
PCT/KR2009/007608
Publication Date:
July 01, 2010
Filing Date:
December 18, 2009
Export Citation:
Assignee:
POSCO (KR)
LEE KYOO-YOUNG (KR)
CHIN KWANG-GEUN (KR)
KIM JONG-SANG (KR)
HONG YOUNG-KWANG (KR)
LEE KYOO-YOUNG (KR)
CHIN KWANG-GEUN (KR)
KIM JONG-SANG (KR)
HONG YOUNG-KWANG (KR)
International Classes:
C22C38/00; C21D8/02; C22C38/14; C23C2/06
Foreign References:
| JP2007197748A | 2007-08-09 | |||
| JPH11286747A | 1999-10-19 | |||
| KR20040027981A | 2004-04-01 | |||
| KR19990045765A |
Attorney, Agent or Firm:
C&S LOGOS PATENT AND LAW OFFICE (KR)
특허법인 씨엔에스·로고스 (KR)
특허법인 씨엔에스·로고스 (KR)
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