Invention Grant
- Patent Title: Dual phase steel sheet and manufacturing method thereof
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Application No.: US14423657Application Date: 2013-09-26
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Publication No.: US09863026B2Publication Date: 2018-01-09
- Inventor: Tatsuo Yokoi , Hiroshi Shuto , Eisaku Sakurada , Hiroyuki Okada
- Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Current Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Birch, Stewart, Kolasch & Birch, LLP
- Priority: JP2012-212783 20120926
- International Application: PCT/JP2013/076149 WO 20130926
- International Announcement: WO2014/051005 WO 20140403
- Main IPC: C22C38/04
- IPC: C22C38/04 ; C22C38/06 ; C22C38/14 ; C21D8/02 ; C21D9/46 ; C23C2/02 ; C23C2/06 ; C23C2/28 ; C22C38/00 ; C22C38/02 ; C22C38/12 ; B32B15/01 ; C21D6/00 ; C22C38/08 ; C22C38/10 ; C22C38/16 ; C22C38/28 ; C22C38/32

Abstract:
A dual phase steel sheet including: in mass %, C: 0.01 to 0.1%; Mn: 0.2 to 3%; Al: 0.04 to 1.5%; Ti: 0.015 to 0.2%; P: 0.01% or less; S: 0.005% or less; N: 0.01% or less, in which [Ti]−48/14×[N]−48/32×[S]≧0% is satisfied and when Ex.C (%)=[C]−12/48×{[Ti]+48/93×[Nb]−48/14×[N]−48/32×[S]} is set, 0.001≦Ex.C (%)/fsd (%)≦0.01 is satisfied, and a balance being composed of Fe and impurities, in which at the position of ¼ thickness of a sheet thickness, a microstructure is a dual phase with its main phase composed of polygonal ferrite precipitation-strengthened by carbide of Ti and its second phase composed of 1 to 10% in area fraction (fsd (%)) of low-temperature transformation products dispersed plurally, and an average crystal diameter of the low-temperature transformation product is 3 to 15 μm and an average value of a distance of closest approach between the low-temperature transformation products is 10 to 20 μm.
Public/Granted literature
- US20150203949A1 DUAL PHASE STEEL SHEET AND MANUFACTURING METHOD THEREOF Public/Granted day:2015-07-23
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