Title:
HIGH-STRENGTH STEEL SHEET AND PROCESS FOR PRODUCING THE SAME
Document Type and Number:
WIPO Patent Application WO/2007/138752
Kind Code:
A1
Abstract:
A high-strength steel sheet which has a metallic structure comprising a ferrite
phase and a second hard phase dispersed in the steel sheet. In the metallic structure,
the areal proportion of the second hard phase is 30-70%. In the ferrite phase,
the areal proportion of ferrite having a crystal grain diameter not larger than
1.2 µm is 15-90% and the average grain diameter of ferrite having a crystal
grain diameter not larger than 1.2 µm (ds) and the average grain diameter
of ferrite having a crystal grain diameter exceeding 1.2 µm (dL) satisfy
the relationship dL/ds≥3. The size of the ferrite crystal grains has
been reduced by reducing the amount of alloying elements to be added. The steel
sheet hence has an increased strength. The steel sheet has an excellent balance
between strength and ductility, which is important for press molding. It is
excellent in energy absorption in high-speed deformation. Also provided is
a process for producing the steel sheet.
Inventors:
OKITSU YOSHITAKA (JP)
Application Number:
PCT/JP2007/000590
Publication Date:
December 06, 2007
Filing Date:
June 01, 2007
Export Citation:
Assignee:
HONDA MOTOR CO LTD (JP)
OKITSU YOSHITAKA (JP)
OKITSU YOSHITAKA (JP)
International Classes:
C22C38/00; B21B3/00; C21D9/46; C22C38/58
Domestic Patent References:
| WO2006059653A1 | 2006-06-08 |
Foreign References:
| JP2002105533A | 2002-04-10 | |||
| JPH11152544A | 1999-06-08 | |||
| JPH1053837A | 1998-02-24 | |||
| JP2004316301A | 2004-11-11 | |||
| JPS62182225A | 1987-08-10 | |||
| JPH07188834A | 1995-07-25 | |||
| JPS613843A | 1986-01-09 | |||
| JPH073381A | 1995-01-06 | |||
| JP2000073152A | 2000-03-07 | |||
| JP2002285278A | 2002-10-03 |
Other References:
"Iron and Steel", THE IRON AND STEEL INSTITUTE OF JAPAN, vol. 88, no. 7, 2002, pages 365
STEEL MATERIALS, MODERN METALLURGY COURSE, MATERIAL, vol. 4, pages 39
STEEL MATERIALS, MODERN METALLURGY COURSE, MATERIAL, vol. 4, pages 35
JOURNAL OF THE JAPAN SOCIETY FOR TECHNOLOGY OF PLASTICITY, vol. 40, no. 467, pages 1190
See also references of EP 2039791A4
STEEL MATERIALS, MODERN METALLURGY COURSE, MATERIAL, vol. 4, pages 39
STEEL MATERIALS, MODERN METALLURGY COURSE, MATERIAL, vol. 4, pages 35
JOURNAL OF THE JAPAN SOCIETY FOR TECHNOLOGY OF PLASTICITY, vol. 40, no. 467, pages 1190
See also references of EP 2039791A4
Attorney, Agent or Firm:
SUENARI, Mikio (6-13 Kyobashi 1-chom, Chuo-ku Tokyo, JP)
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