Title:
FIRE-RESISTANT STEEL MATERIAL WITH EXCELLENT RESISTANCE TO REHEAT EMBRITTLEMENT AND WITH LOW-TEMPERATURE TOUGHNESS AT WELDED HEAT-AFFECTED PARTS, AND MANUFACTURING METHOD THEREOF
Document Type and Number:
WIPO Patent Application WO/2010/050394
Kind Code:
A1
Abstract:
Provided are a fire-resistant steel material to which is applied high heat input welding and that demonstrates excellent low-temperature toughness and resistance to reheat embrittlement when exposed to fire at welded heat-affected parts, and a method for manufacturing the same. The steel material contains C: 0.012-0.050%, Mn: 0.80-2.00%, Cr: 0.80-1.90%, and Nb: 0.01 to less than 0.05%; Cu: restricted to 0.10% or less; contains suitable amounts of Si, N, Ti, and Al; the content of Mo, B, P, S, and O are restricted; and the remainder comprises Fe and inevitable impurities. The content of C, Mn, Cr, Nb, and Cu satisfy -1200C - 20Mn + 30Cr -330Nb - 120Cu ≥ -80. The steel structure as observed using an optical microscope is 80% or more ferrite phase by surface area ratio, and the remainder of said steel material is made of a mixed structure comprising a bainite phase, a martensite phase, and a martensite-austenite phase.
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Inventors:
MIZOGUCHI MASAKI (JP)
HASEGAWA YASUSHI (JP)
WATANABE YOSHIYUKI (JP)
HASEGAWA YASUSHI (JP)
WATANABE YOSHIYUKI (JP)
Application Number:
PCT/JP2009/068150
Publication Date:
May 06, 2010
Filing Date:
October 15, 2009
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
MIZOGUCHI MASAKI (JP)
HASEGAWA YASUSHI (JP)
WATANABE YOSHIYUKI (JP)
MIZOGUCHI MASAKI (JP)
HASEGAWA YASUSHI (JP)
WATANABE YOSHIYUKI (JP)
International Classes:
C22C38/00; B21B3/00; C21D8/02; C22C38/58
Foreign References:
| JPH07278660A | 1995-10-24 | |||
| JP2008144216A | 2008-06-26 | |||
| JP2008121120A | 2008-05-29 | |||
| JPH09176730A | 1997-07-08 | |||
| JP2008179878A | 2008-08-07 | |||
| JP2007211278A | 2007-08-23 |
Attorney, Agent or Firm:
AOKI, Atsushi et al. (JP)
Atsushi Aoki (JP)
Atsushi Aoki (JP)
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