Title:
高強度熱延鋼板の製造方法
Document Type and Number:
Japanese Patent JP5176431
Kind Code:
B2
Abstract:
A method for manufacturing a high strength steel sheet that has strength of 490 MPa or higher, has a hole expanding ratio » after 10% working of 80% or higher, is excellent in terms of stretch-flangeability, and stable in terms of localized variation of material characteristics within a coil is provided. A method for manufacturing a high strength hot rolled steel sheet including a step of heating a slab to a temperature in the range of 1150 to 1300°C; a step of hot rolling the slab with a finishing rolling temperature being in the range of 800 to 1000°C; a step of cooling the steel sheet at a mean cooling rate of 30°C/s or higher to a cooling termination temperature in the range of 525 to 625°C; a step of suspending cooling for a time period in the range of 3 to 10 seconds; a step of cooling the steel sheet in such a manner that cooling of the steel sheet is nucleate boiling; and a step of coiling the steel sheet at a temperature in the range of 400 to 550°C, wherein the slab contains the following elements at the following content ratios by weight percent:
C: 0.05 to 0.15%; Si: 0.1 to 1.5%; Mn: 0.5 to 2.0%; P: 0.06% or lower; S: 0.005% or lower; Al: 0.10% or lower; and Fe and unavoidable impurities as the balance.
Inventors:
Takeshi Yokota
Kazuhiro Seto
Satoshi Ueoka
Nobuo Nishiura
Youichi Tominaga
Kazuhiro Seto
Satoshi Ueoka
Nobuo Nishiura
Youichi Tominaga
Application Number:
JP2007218062A
Publication Date:
April 03, 2013
Filing Date:
August 24, 2007
Export Citation:
Assignee:
jfe Steel Corporation
International Classes:
C21D9/46; B21B45/02; C21D8/02; C22C38/00; C22C38/06; C22C38/14
Domestic Patent References:
| JP2001164322A | ||||
| JP2002069534A | ||||
| JP2002539330A | ||||
| JP4276024A | ||||
| JP2000317513A | ||||
| JP8176723A | ||||
| JP4337026A |
Attorney, Agent or Firm:
Shigeru Inoue
Kazuhiro Mori
Kazuhiro Mori