Invention Grant
- Patent Title: High-strength high-toughness hot-rolled steel sheet and manufacturing method therefor
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Application No.: US16957939Application Date: 2018-09-17
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Publication No.: US11578392B2Publication Date: 2023-02-14
- Inventor: Jin-Ho Bae
- Applicant: POSCO
- Applicant Address: KR Pohang-si
- Assignee: POSCO
- Current Assignee: POSCO
- Current Assignee Address: KR Pohang-si
- Agency: Morgan, Lewis & Bockius LLP
- Priority: KR10-2017-0179337 20171226
- International Application: PCT/KR2018/010935 WO 20180917
- International Announcement: WO2019/132179 WO 20190704
- Main IPC: C22C38/50
- IPC: C22C38/50 ; C21D9/46 ; C22C38/00 ; C22C38/02 ; C22C38/04 ; C22C38/06 ; C22C38/42 ; C22C38/48 ; C21D8/02

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 pearlite, 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.
Public/Granted literature
- US20210062312A1 HIGH-STRENGTH HIGH-TOUGHNESS HOT-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREFOR Public/Granted day:2021-03-04
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