Title:
HIGH-STRENGTH ELECTRICAL-RESISTANCE-WELDED STEEL PIPE AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2011/118841
Kind Code:
A1
Abstract:
The disclosed high-strength electrical-resistance-welded steel pipe is suitable for use as an automobile shock-absorbing member. Said steel pipe contains, by mass, between 0.05% and 0.20% carbon, between 0.5% and 2.0% silicon, between 1.0% and 3.0% manganese, at most 0.1% phosphorus, at most 0.01% sulfur, between 0.01% and 0.1% aluminum, and at most 0.005% nitrogen, with the remainder comprising iron and unavoidable impurities. Said steel pipe has a two-phase structure comprising a ferrite phase and a martensite phase, with the volume fraction of the martensite phase between 20% and 60%. The disclosed steel pipe has a tensile strength (TS) of at least 1,180 MPa, an axial elongation (El) of at least 10%, and a yield ratio of less than 90%. After a coating baking process in which the steel pipe is prestressed by 2% and then heat-treated at 170°C for 10 minutes, the amount of strength increase (BH amount) is at least 100 MPa and the yield ratio increases to at least 90%.
Inventors:
ARATANI MASATOSHI (JP)
KAWABATA YOSHIKAZU (JP)
MATSUOKA SAIJI (JP)
HIRATA NORIMASA (JP)
KAWABATA YOSHIKAZU (JP)
MATSUOKA SAIJI (JP)
HIRATA NORIMASA (JP)
Application Number:
PCT/JP2011/057928
Publication Date:
September 29, 2011
Filing Date:
March 23, 2011
Export Citation:
Assignee:
JFE STEEL CORP (JP)
ARATANI MASATOSHI (JP)
KAWABATA YOSHIKAZU (JP)
MATSUOKA SAIJI (JP)
HIRATA NORIMASA (JP)
ARATANI MASATOSHI (JP)
KAWABATA YOSHIKAZU (JP)
MATSUOKA SAIJI (JP)
HIRATA NORIMASA (JP)
International Classes:
C22C38/06; B21C37/08; C21D8/02; C21D9/46; C22C38/58
Foreign References:
| JPH04276017A | 1992-10-01 | |||
| JP2006299414A | 2006-11-02 | |||
| JP2008111162A | 2008-05-15 | |||
| JP2009030148A | 2009-02-12 | |||
| JPH03122219A | 1991-05-24 | |||
| JP2010255094A | 2010-11-11 | |||
| JP2010126787A | 2010-06-10 | |||
| JP2009242816A | 2009-10-22 | |||
| JP2009203550A | 2009-09-10 | |||
| JP2007100114A | 2007-04-19 | |||
| JP2005163055A | 2005-06-23 |
Other References:
See also references of EP 2551366A4
KAWASAKI-- STEEL GIHO, vol. 32, 2000, pages 49 - 53
KAWASAKI-- STEEL GIHO, vol. 32, 2000, pages 49 - 53
Attorney, Agent or Firm:
OCHIAI, Kenichiro (JP)
Ken-ichiro Ochiai (JP)
Ken-ichiro Ochiai (JP)
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Claims:
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