Title:
HIGH STRENGTH AND HIGH DUCTILITY STEEL AND STEEL SHEET HAVING EXCELLENT LOCAL DUCTILITY, AND METHOD OF PRODUCING THE STEEL SHEET
Document Type and Number:
Japanese Patent JP3857939
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide steel and a steel sheet having high strength and high ductility and also provided with excellent local ductility, and to provide a method of producing the steel sheet.
SOLUTION: Each of the steel and the steel sheet has a composition containing, by mass, 0.06 to 0.20% C, ≤2.0% Si, and 3.0 to 7.0% Mn, and the balance Fe as essential components, and in which the volume ratio of retained austenite is 10 to <20%, and the area ratio of tempered martensite and tempered bainite is ≥30%. The content of Si is preferably controlled in ≤1.00% for improving its plating properties. The steel sheet is produced by subjecting an ingot having the above components to hot rolling, or further, cold rolling at a draft of ≤20%, and thereafter subjecting the rolling stock to tempering heat treatment of holding at 700 to (an Al point -50)°C for ≥20 sec.
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Inventors:
Koichi Makii
Shuyuki Ikeda
Hiro Akamizu
Shunichi Hashimoto
Yuri
Shuyuki Ikeda
Hiro Akamizu
Shunichi Hashimoto
Yuri
Application Number:
JP2002085209A
Publication Date:
December 13, 2006
Filing Date:
March 26, 2002
Export Citation:
Assignee:
KABUSHIKI KAISHA KOBE SEIKO SHO
International Classes:
C21D9/46; C22C38/00; C22C38/04; C22C38/58; (IPC1-7): C22C38/00; C21D9/46; C22C38/04; C22C38/58
Domestic Patent References:
| JP5311323A | ||||
| JP4235253A | ||||
| JP7003326A | ||||
| JP5070886A | ||||
| JP1259121A | ||||
| JP2163343A |
Attorney, Agent or Firm:
Honda Ryu Male