Title:
PRECIPITATION-HARDENING HOT ROLLED STEEL SHEET HAVING EXCELLENT MATERIAL UNIFORMITY AND HOLE EXPANDABILITY, AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2017/222343
Kind Code:
A1
Abstract:
One aspect of the present invention relates to a precipitation-hardening hot rolled steel sheet having excellent material uniformity and hole expandability, comprising, by wt%, 0.02-0.05% of C, 0.01-0.3% of Si, 1.0-1.6% of Mn, 0.04-0.1% of Ti, 0.01-0.05% of Nb, 0.008% or less of N and the balance of Fe and other inevitable impurities, wherein the following formula (1) is satisfied, the microstructure comprises 95 area% or more of ferrite and (Ti, Nb)C composite precipitates, and the (Ti, Nb)C composite precipitates are formed such that the number of (Ti, Nb)C composite precipitates having a diameter of 10 nm or less is five times or more the number of (Ti, Nb)C composite precipitates having a diameter of more than 10 nm.
Formula (1): 0.35 ≤ (Ti+Nb+V+Mo)/(C+N) ≤ 0.70
(In formula (1), each element symbol means the at.% of each element and the element, which is not contained in steel, is calculated as zero.)
Inventors:
NA HYUN-TAEK (KR)
SEONG HWAN-GOO (KR)
SEO SEOK-JONG (KR)
KIM SUNG-IL (KR)
SEONG HWAN-GOO (KR)
SEO SEOK-JONG (KR)
KIM SUNG-IL (KR)
Application Number:
PCT/KR2017/006668
Publication Date:
December 28, 2017
Filing Date:
June 23, 2017
Export Citation:
Assignee:
POSCO (KR)
International Classes:
C22C38/14; C21D8/02; C22C38/00; C22C38/02; C22C38/04; C22C38/12
Foreign References:
| JP2000087142A | 2000-03-28 | |||
| KR20140085188A | 2014-07-07 | |||
| KR100711481B1 | 2007-04-24 | |||
| KR20150025910A | 2015-03-11 | |||
| KR20140081048A | 2014-07-01 | |||
| JPH06200351A | 1994-07-19 | |||
| JP2003321739A | 2003-11-14 | |||
| KR20120049993A | 2012-05-18 | |||
| KR20120052022A | 2012-05-23 |
Other References:
See also references of EP 3476969A4
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
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