Title:
METHOD FOR WORKING ULTRAHIGH-STRENGTH STEEL SHEET SHOWING SUPERPLASTICITY
Document Type and Number:
Japanese Patent JP2007031802
Kind Code:
A
Abstract:
To provide a method for working an ultrahigh-strength steel sheet showing superplasticity, without oxidizing the surface, causing the unevenness of the strength, and lowering the strength of the steel sheet after having been worked.
The ultrahigh-strength steel sheet includes, by mass%, 0.02-0.15% C, 0.05-0.7% Mo and 0.03-0.35% Ti; has substantially a single phase structure of ferrite in which precipitates containing Ti and Mo with an average particle diameter of less than 10 nm are dispersed; and has a tensile strength of 780 MPa or higher at room temperature. The working method comprises the steps of: superplastically forming the ultrahigh-strength steel sheet while heating it at 500 to 750°C; and cooling it to room temperature.
Inventors:
SETO KAZUHIRO
SUZUKI KENJI
OKADA YOSHIO
NAKANISHI EIZABURO
SUZUKI KENJI
OKADA YOSHIO
NAKANISHI EIZABURO
Application Number:
JP2005219804A
Publication Date:
February 08, 2007
Filing Date:
July 29, 2005
Export Citation:
Assignee:
JFE STEEL KK
NISSAN MOTOR
NISSAN MOTOR
International Classes:
C21D9/46; B21D26/02; B21D26/021; B21D26/055; C22C38/00; C22C38/14
Domestic Patent References:
| JP2003089848A | 2003-03-28 | |||
| JP2004043978A | 2004-02-12 | |||
| JPS57177834A | 1982-11-01 |
Attorney, Agent or Firm:
Hiroshi Takayama