Title:
HIGH TENSION STEEL PLATE, WELDED STEEL PIPE AND METHOD FOR PRODUCTION THEREOF
Document Type and Number:
WIPO Patent Application WO/2006/098198
Kind Code:
A1
Abstract:
A high tension steel plate, which has a content of carbon equivalent Pcm represented by the following formula (1) of 0.180 to 0.220 % and a surface hardness of 285 or less in terms of Vickers, and has a structure wherein the percentage of a martensite austenite constituent in a surface layer portion is 10 % or less, the percentage of a mixed structure of ferrite and bainite in a portion inside the surface layer portion is 90 % or more and the percentage of bainite in the mixed structure is 10 % or more, a lath of bainite has a thickness of 1 μm or less and a length of 20 μm or less, and the segregation level, which is the ratio of an Mn concentration in the central segregated portion to an Mn concentration in a part having a depth from the surface of 1/4 of the thickness of the plate, is 1.3 or less. Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B (1) wherein each symbol in the formula (1) represents the mass % of each element. The high tension steel plate has a yield strength of 551 MPa or greater and a tensile strength of 620MPa or greater, and is excellent in toughness, high-speed ductile fracture characteristics and weldability.
Inventors:
TAKAHASHI NOBUAKI (JP)
HAMADA MASAHIKO (JP)
OKAGUCHI SHUJI (JP)
YAMANAKA AKIHIRO (JP)
SETA ICHIROU (JP)
HAMADA MASAHIKO (JP)
OKAGUCHI SHUJI (JP)
YAMANAKA AKIHIRO (JP)
SETA ICHIROU (JP)
Application Number:
PCT/JP2006/304452
Publication Date:
September 21, 2006
Filing Date:
March 08, 2006
Export Citation:
Assignee:
SUMITOMO METAL IND (JP)
TAKAHASHI NOBUAKI (JP)
HAMADA MASAHIKO (JP)
OKAGUCHI SHUJI (JP)
YAMANAKA AKIHIRO (JP)
SETA ICHIROU (JP)
TAKAHASHI NOBUAKI (JP)
HAMADA MASAHIKO (JP)
OKAGUCHI SHUJI (JP)
YAMANAKA AKIHIRO (JP)
SETA ICHIROU (JP)
International Classes:
B21B3/00; C22C38/00; B21C37/08; B22D11/00; B22D11/115; B22D11/128; C21D8/02; C22C38/58
Foreign References:
| JP2004131799A | 2004-04-30 | |||
| JP2003293089A | 2003-10-15 | |||
| JP2005008931A | 2005-01-13 | |||
| JP2003328080A | 2003-11-19 | |||
| JP2004124167A | 2004-04-22 | |||
| JP2004124168A | 2004-04-22 | |||
| JP2004043911A | 2004-02-12 | |||
| JP2002220634A | 2002-08-09 | |||
| JP2004131799A | 2004-04-30 | |||
| EP1354973A1 | 2003-10-22 | |||
| JP2005008931A | 2005-01-13 |
Other References:
See also references of EP 1860204A4
Attorney, Agent or Firm:
Ueba, Hidetoshi (4th Fl. Kadono Bldg., 2-1 Tenma 2-chome, Kita-k, Osaka-shi Osaka 43, JP)
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