Title:
HIGH-STRENGTH HIGH-TOUGHNESS HOT-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2019/132179
Kind Code:
A1
Abstract:
A preferable aspect of the present invention provides a high-strength high-toughness hot-rolled steel sheet and a manufacturing method therefor, wherein the hot-rolled steel sheet contains, by weight, 0.07-0.13% C, 0.20-0.50% Si, 0.5-0.9% Mn, 0.03% or less P, 0.02% or less S, 0.005-0.03% Nb, 0.3-0.6% Cr, 0.005-0.03% Ti, 0.1-0.35% Cu, 0.05-0.3% Ni, 0.01-0.15% Mo, 0.007% or less N, 0.001-0.006% Ca, 0.01-0.05% Al, and the balance Fe and other unavoidable impurities, the alloy elements satisfying the following relational formulas - [Relational formula 1] 1.6 ≤ (Mo/96)/(P/31) ≤ 6, [Relational formula 2] 1.6 ≤ (Ca/S) ≤ 3, and [Relational formula 3] 3.5 ≤ (3*C/12+Mn/55)*100 ≤ 5; wherein a microstructure comprises, by area fraction, 85% or more of polygonal ferrite and 15% or less of perlite, the crystal grain size of the polygonal ferrite being 10 μm or less; and wherein a variation in yield strength in a width direction is 35 MPa or lower.
More Like This:
Inventors:
BAE JIN-HO (KR)
Application Number:
PCT/KR2018/010935
Publication Date:
July 04, 2019
Filing Date:
September 17, 2018
Export Citation:
Assignee:
POSCO (KR)
International Classes:
C21D8/02; C21D9/46; C22C38/00; C22C38/04; C22C38/44
Foreign References:
| KR101585724B1 | 2016-01-14 | |||
| JP2010106287A | 2010-05-13 | |||
| JP2004351501A | 2004-12-16 | |||
| KR100833035B1 | 2008-05-27 | |||
| JP2002003985A | 2002-01-09 | |||
| KR101568544B1 | 2015-11-11 | |||
| KR20160077385A | 2016-07-04 |
Other References:
See also references of EP 3733912A4
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
Download PDF:
Previous Patent: POLYMER, ORGANIC FILM COMPOSITION, AND METHOD FOR FORMING PATTERN
Next Patent: PAINT COMPOSITION
Next Patent: PAINT COMPOSITION