Title:
HIGH-STRENGTH STEEL SHEET AND MANUFACTURING METHOD THEREOF
Document Type and Number:
WIPO Patent Application WO/2021/020789
Kind Code:
A1
Abstract:
The present invention provides a high-strength steel sheet and a manufacturing method thereof, the high-strength steel sheet comprising C, Si, Mn, Cr, Al, Nb, Ti, B, P, S, N and a balance of Fe and other inevitable impurities, wherein the amounts of C, Si and Al satisfy mathematical equation (1) below, and the high-strength steel sheet has a microstructure comprising, by area fraction: more than 1% to 4% or less of retained austenite; more than 10% to 20% or less of fresh martensite; 5% or less (excluding 0%) of ferrite; more than 50% to 70% or less of tempered martensite; and a balance of bainite, wherein the number density of the retained austenite is 0.25/µm2 or less, the average effective diameter of the retained austenite is 0.2-0.4 µm, and the proportion of the retained austenite having an effective diameter smaller than the average effective diameter is more than 60%. [Mathematical equation (1)] [C] + ([Si]+[Al])/5 ≤ 0.35wt.% (Here, [C], [Si] and [Al] respectively mean the wt% of C, Si and Al.)
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Inventors:
IM YOUNG-ROC (KR)
LEE JAE-HOON (KR)
PARK JONG-CHAN (KR)
KIM JONG-KWEON (KR)
KIM IL-HYUN (KR)
HAN TAE-KYO (KR)
LEE TAE-OH (KR)
LEE JAE-HOON (KR)
PARK JONG-CHAN (KR)
KIM JONG-KWEON (KR)
KIM IL-HYUN (KR)
HAN TAE-KYO (KR)
LEE TAE-OH (KR)
Application Number:
PCT/KR2020/009557
Publication Date:
February 04, 2021
Filing Date:
July 20, 2020
Export Citation:
Assignee:
POSCO (KR)
International Classes:
C22C38/38; C21D1/68; C21D8/02; C21D9/46; C23C2/06
Foreign References:
| KR20190076307A | 2019-07-02 | |||
| KR20160132926A | 2016-11-21 | |||
| JP2014034716A | 2014-02-24 | |||
| US20180002778A1 | 2018-01-04 | |||
| KR20130027794A | 2013-03-18 | |||
| KR20177015003A | 2015-10-27 |
Other References:
See also references of EP 4006192A4
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
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