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Title:
JOINT WELDED BY ELECTRON BEAM WITH EXCELLENT UNSUSCEPTIBILITY TO BRITTLE FRACTURE
Document Type and Number:
WIPO Patent Application WO/2008/041372
Kind Code:
A1
Abstract:
High-strength steel plates having a yield strength of 355 MPa or higher and a thickness larger than 50 mm are butt-welded by electron beam welding to form a welded joint having a sufficiently high fracture toughness value δc. The butt-welded joint has been regulated so that the hardness of the weld metal part is 110-220% based on the hardness of the base plates and the width of the weld metal part is up to 20% of the thickness of the base plates. Preferably, the weld metal of the welded joint has been regulated so that the amount of oxygen contained therein is 20 ppm or larger and the number of oxide particles having a diameter of 2.0 µm or larger present therein is up to 10 per mm2. Alternatively, the weld metal of the welded joint has preferably been regulated so as to have a nickel content which is 1-4 mass% and is higher by at least 0.2 mass% than that in the base plates. When the base plates are a steel material having a nickel content of 2.5 mass% or higher, the nickel content in the weld metal of the welded joint has preferably been regulated to 4-8 mass%, excluding 4 mass%.

Inventors:
ISHIKAWA, Tadashi (20-1 Shintomi, Futtsu-sh, Chiba 11, 2938511, JP)
石川忠 (〒11 千葉県富津市新富20-1新日本製鐵株式会社 技術開発本部内 Chiba, 2938511, JP)
HONMA, Ryuichi (20-1 Shintomi, Futtsu-sh, Chiba 11, 2938511, JP)
本間竜一 (〒11 千葉県富津市新富20-1新日本製鐵株式会社 技術開発本部内 Chiba, 2938511, JP)
KOJIMA, Akihiko (20-1 Shintomi, Futtsu-sh, Chiba 11, 2938511, JP)
Application Number:
JP2007/050738
Publication Date:
April 10, 2008
Filing Date:
January 12, 2007
Export Citation:
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Assignee:
NIPPON STEEL CORPORATION (6-3 Otemachi 2-chome, Chiyoda-ku Tokyo, 71, 1008071, JP)
新日本製鐵株式会社 (〒71 東京都千代田区大手町二丁目6番3号 Tokyo, 1008071, JP)
ISHIKAWA, Tadashi (20-1 Shintomi, Futtsu-sh, Chiba 11, 2938511, JP)
石川忠 (〒11 千葉県富津市新富20-1新日本製鐵株式会社 技術開発本部内 Chiba, 2938511, JP)
HONMA, Ryuichi (20-1 Shintomi, Futtsu-sh, Chiba 11, 2938511, JP)
本間竜一 (〒11 千葉県富津市新富20-1新日本製鐵株式会社 技術開発本部内 Chiba, 2938511, JP)
International Classes:
B23K15/00
Domestic Patent References:
WO1999016101A21999-04-01
Foreign References:
JP2002003984A2002-01-09
JPH02282466A1990-11-20
JPS5861981A1983-04-13
JPH0285339A1990-03-26
JPH03248783A1991-11-06
JP2003201535A2003-07-18
JP2005125393A2005-05-19
JPH03248783A1991-11-06
JP2005144552A2005-06-09
JPS6264486A1987-03-23
JP2003201535A2003-07-18
Other References:
See also references of EP 2070631A4
Attorney, Agent or Firm:
AOKI, Atsushi et al. (SEIWA PATENT & LAW, Toranomon 37 Mori Bldg.5-1, Toranomon 3-chom, Minato-ku Tokyo 23, 1058423, JP)
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