THICK HIGH STRENGTH STEEL PLATE HAVING EXCELLENT LOW TEMPERATURE TOUGHNESS IN WELDING HEAT AFFECTED ZONE CAUSED BY HIGH HEAT INPUT WELDING

Title:

THICK HIGH STRENGTH STEEL PLATE HAVING EXCELLENT LOW TEMPERATURE TOUGHNESS IN WELDING HEAT AFFECTED ZONE CAUSED BY HIGH HEAT INPUT WELDING

Document Type and Number:

WIPO Patent Application WO/2005/098068

Kind Code:

A1

Abstract:

A thick high strength steel plate having excellent low temperature toughness in a welding heat affected zone caused by high heat input welding, which is characterized in that it has a chemical composition, in mass %, that C: 0.03 to 0.14 %, Si: 0.30 % or less, Mn: 0.8 to 2.0 %, P: 0.02 % or less, S: 0.005 % or less, Ni: 0.8 to 4.0 %, Nb: 0.003 to 0.040 %, Al: 0.001 to 0.040 %, N: 0.0010 to 0.0100 %, Ti: 0.005 to 0.030 %, with the proviso that the contents of Ni and Mn satisfy the following formula [1], and the balance: iron and inevitable impurities, Ni/Mn ≥ 10 X Ceq - 3 (0.36 < Ceq < 0.42) wherein Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15. The use of the above thick high strength steel plate can achieve excellent welding HAZ toughness, even when a welding is carried out with a welding heat input of 20 to 100 kJ/mm on a steel plate having a thickness of 50 to 80 mm and exhibiting a base material tensile strength of about 490 to 570 Mpa.

Inventors:

ITO MINORU (JP)
KOJIMA AKIHIKO (JP)
MINAGAWA MASANORI (JP)
TANAKA YOICHI (JP)
HASEGAWA TOSHIEI (JP)
OTANI JUN (JP)

Application Number:

PCT/JP2005/007109

Publication Date:

October 20, 2005

Filing Date:

April 06, 2005

Export Citation:

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Assignee:

NIPPON STEEL CORP (JP)
ITO MINORU (JP)
KOJIMA AKIHIKO (JP)
MINAGAWA MASANORI (JP)
TANAKA YOICHI (JP)
HASEGAWA TOSHIEI (JP)
OTANI JUN (JP)

International Classes:

B21B1/38; B21B3/00; C21D8/02; C22C38/00; C22C38/14; C22C38/58; (IPC1-7): C22C38/00; C22C38/14; C22C38/58

Foreign References:

JPH093597A	1997-01-07
JP2003313628A	2003-11-06

Other References: