Invention Grant
- Patent Title: High strength hot rolled steel products for line-pipes excellent in low temperature toughness and production method of the same
- Patent Title (中): 用于线管的高强度热轧钢产品具有优异的低温韧性和生产方法
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Application No.: US12449815Application Date: 2008-02-29
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Publication No.: US08562762B2Publication Date: 2013-10-22
- Inventor: Tatsuo Yokoi , Masanori Minagawa , Takuya Hara , Osamu Yoshida , Hiroshi Abe
- Applicant: Tatsuo Yokoi , Masanori Minagawa , Takuya Hara , Osamu Yoshida , Hiroshi Abe
- Applicant Address: JP Tokyo
- Assignee: Nippon Steel & Sumitomo Metal Corporation
- Current Assignee: Nippon Steel & Sumitomo Metal Corporation
- Current Assignee Address: JP Tokyo
- Agency: Kenyon & Kenyon LLP
- Priority: JP2007-052040 20070301
- International Application: PCT/JP2008/054104 WO 20080229
- International Announcement: WO2008/132882 WO 20081106
- Main IPC: C22C38/00
- IPC: C22C38/00 ; C22C38/04 ; C22C38/14 ; C21D11/00 ; C21D8/00

Abstract:
The present invention provides high strength hot rolled steel plate for line-pipes superior in low temperature toughness, and a method of production of the same, containing, by mass %, C: 0.01 to 0.1%, Si: 0.05 to 0.5%, Mn: 1 to 2%, P: ≦0.03%, S: ≦0.005%, O: ≦0.003%, Al: 0.005 to 0.05%, N: 0.0015 to 0.006%, Nb: 0.005 to 0.08%, and Ti: 0.005 to 0.02%, where N−14/48×Ti>0% and Nb−93/14×(N−14/48×Ti)>0.005%, and a balance of Fe and unavoidable impurities, said steel plate characterized in that its microstructure is a continuously cooled transformed structure, a reflected X-ray intensity ratio {211}/{111} of the {211} plane and {111} plane parallel to the plate surface in the texture at the center of plate thickness is 1.1 or more, and an in-grain precipitate density of the precipitates of Nb and/or Ti carbonitrides is 1017 to 1018/cm3.
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