Title:
HOT DIPPED GALVANIZED STEEL SHEET WITH EXCELLENT HOLE EXPANSIBILITY, HOT DIPPED GALVANNEALED STEEL SHEET, AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2016/098963
Kind Code:
A1
Abstract:
A hot dipped galvanized steel sheet with an excellent hole expansibility, a hot dipped galvannealed steel sheet, and a manufacturing method therefor are provided. The present invention relates to a hot dipped galvanized steel sheet having excellent hole expansibility and comprising a hot dipped galvanized layer formed on the surface of a base steel sheet, wherein the base steel sheet is composed of 0.02-0.08 wt% of carbon (C), 1.3-2.1 wt% of manganese (Mn), 0.3 wt% or less of silicon (Si) (excluding 0 wt%), 1.0 wt% or less of chromium (Cr) (excluding 0 wt%), 0.1 wt% or less of phosphorus (P) (excluding 0 wt%), 0.01 wt% or less of sulfur (S) (excluding 0 wt%), 0.01 wt% or less of nitrogen (N) (excluding 0 wt%), 0.02-0.06 wt% of aluminum (sol. Al), 0.2 wt% or less of molybdenum (Mo) (excluding 0 wt%), 0.003 wt% or less of boron (B) (excluding 0 wt%), and the balance of Fe and other inevitable impurities, the microstructure of the base steel sheet is composed of 90% or more of ferrite, the balance of martensite, and 3% or less of bainite defined by relation 1 according to area percentage, and the ratio (a/b) of the concentration (a) of C+Mn in the base structure within 10 μm, on average, on a surface layer of the base steel sheet and the concentration (b) of C+Mn in the base structure at the 1/4t point of the thickness of the base steel sheet is 0.7 or less.
Inventors:
HAN SANG-HO (KR)
HAN SEONG-HO (KR)
HAN SEONG-HO (KR)
Application Number:
PCT/KR2015/004592
Publication Date:
June 23, 2016
Filing Date:
May 08, 2015
Export Citation:
Assignee:
POSCO (KR)
International Classes:
C22C38/38; C21D8/02; C22C38/22; C23C2/06
Foreign References:
| KR20140027526A | 2014-03-06 | |||
| JP2013163827A | 2013-08-22 | |||
| KR20110119285A | 2011-11-02 | |||
| KR100711468B1 | 2007-04-24 |
Other References:
See also references of EP 3235922A4
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
특허법인 씨엔에스 (KR)
특허법인 씨엔에스 (KR)
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