Title:
自動車構造部材用鋼材およびその製造方法
Document Type and Number:
Japanese Patent JP4443910
Kind Code:
B2
Abstract:
The present invention provides a steel having excellent formability, fatigue endurance after quenching, low temperature toughness, resistance for hydrogen embrittlement, and corrosion fatigue endurance. Resolving means includes heating a steel slab at 1160°C to 1320°C, hot-finish-rolling the steel slab at a finisher delivery temperature of 750°C to 980°C, and then coiling the hot-rolled steel at a coiling temperature of 560°C to 740°C after slow cooling for a time of 2 seconds or more to produce a hot-rolled steel strip having a structure in which the ferrite grain diameter df corresponding to a circle is 1.1 µm to less than 1.2 µm and the ferrite volume fraction Vf is 30% to 98%, the steel slab containing 0.18 to 0.29% of C, 0.06 to 0.45% of Si, 0.91 to 1.85% of Mn, 0.019% or less of P, 0.0029% or less of S, 0.015 to 0.075% of sol. Al, 0.0049% or less of N, 0.0049% or less of O, 0.0001 to 0.0029% of B, 0.001 to 0.019% of Nb, 0.001 to 0.029% of Ti, 0.001 to 0.195% of Cr, and 0.001 to 0.195% of Mo so that the carbon equivalent Ceq satisfies a value of 0.4 to less than 0.58, and the total x of multiplying factors including that for B according to Grossmann satisfies a value of 1.2 to less than 1.7. The hot-rolled steel strip is used as a raw material for producing a steel tube by electric resistance welded tube making with a width reduction of hoop of 8% or less.
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Inventors:
Shunsuke Toyota
Akio Sato
Takashi Sakata
Kaneko Koichi
Hiroshi Kawaguchi
Akio Sato
Takashi Sakata
Kaneko Koichi
Hiroshi Kawaguchi
Application Number:
JP2003414336A
Publication Date:
March 31, 2010
Filing Date:
December 12, 2003
Export Citation:
Assignee:
jfe Steel Corporation
TOYOTA JIDOSHA KABUSHIKI KAISHA
TOYOTA JIDOSHA KABUSHIKI KAISHA
International Classes:
C21D9/46; C22C38/00; C21D7/02; C21D8/02; C22C38/38; C22C38/58; C21D8/10
Domestic Patent References:
| JP2000204442A | ||||
| JP2003321748A | ||||
| JP6264142A | ||||
| JP10088278A |
Foreign References:
| WO2002070767A1 |
Attorney, Agent or Firm:
Eiichi Kobayashi