Title:
ULTRA-HIGH STRENGTH STEEL SHEET HAVING EXCELLENT CHEMICAL CONVERSION TREATABILITY AND BENDING PROCESSABILITY AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2017/105025
Kind Code:
A1
Abstract:
The present invention relates to an ultra-high strength steel sheet used as steel sheets for vehicles and the like. Provided is an ultra-high strength steel sheet, having excellent chemical conversion treatability and hole expansibility, comprising 0.08~0.2 wt% of carbon (C), 0.05~1.3 wt% of silicon (Si), 2.0~3.0 wt% of manganese (Mn), 0.001~0.10 wt% of phosphorous (P), 0.010 wt% or less of sulfur (S), 0.01~0.1 wt% of aluminum (Al), 0.3~1.2 wt% of chromium (Cr), 0.0010~0.0030 wt% of boron (B), 0.01~0.05 wt% of titanium (Ti), and 0.001~0.01 wt% of nitrogen (N) with a balance of Fe and other inevitable impurities, wherein the Ti and N satisfy relational expression (1) 3.4≤Ti/N≤10, the Mn, Si and Cr satisfy relational expression (2) 1.0≤Mn/(Si+Cr), and the Mn, Si and Cr contents (Mn*, Si* and Cr*) in a surface layer (from the surface to 0.1㎛ in the thickness direction) satisfy relational expression (3) 0.7≤Mn*/(Si*+Cr*)≤Mn/(Si+Cr).
Inventors:
SEO SEOK-JONG (KR)
Application Number:
PCT/KR2016/014280
Publication Date:
June 22, 2017
Filing Date:
December 07, 2016
Export Citation:
Assignee:
POSCO (KR)
International Classes:
C22C38/38; C21D8/02; C22C38/02; C22C38/04; C22C38/06; C22C38/28; C22C38/32
Foreign References:
| KR20120049622A | 2012-05-17 | |||
| JP2015180766A | 2015-10-15 | |||
| KR20140037180A | 2014-03-26 | |||
| JP2005248281A | 2005-09-15 | |||
| CN104271787A | 2015-01-07 |
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
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