Title:
高張力熱延鋼板およびその製造方法
Document Type and Number:
Japanese Patent JP5700139
Kind Code:
B2
Abstract:
A steel material that contains, by mass, 0.035-0.065% carbon, up to 0.2% silicon, up to 0.7% manganese, up to 0.02% sulfur, up to 0.01% nitrogen, up to 0.1% aluminum, 0.1-0.2% titanium, and may also contain up to 0.0035% boron is subjected to rough rolling and tandem rolling using a rolling mill in which finishing rolling is performed in five or more sequential steps. The temperature at the entrance to the finishing-rolling mill is at least 1,000°C, the temperature at the exit therefrom is at least 900°C, and after the completion of finishing rolling, the steel material is cooled and taken up at a take-up temperature of no more than 700°C. This results in a high-tension hot-rolled steel sheet that: has a metal structure comprising ferrite crystal grains with an area fraction of at least 95%, wherein titanium carbide with a mean grain diameter of less than 6 nm is finely dispersedly precipitated inside the ferrite crystal grains and titanium(II) sulfide with a mean grain diameter of 0.5 µm or less is finely dispersedly precipitated within the metal structure; exhibits high strength, with a tensile strength (TS) of 780 to 900 MPa; and exhibits excellent bending workability.
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Inventors:
Yoshimasa Funagawa
Hiroshi Owada
Tetsuo Yamamoto
Ubari Hiroshi
Hiroshi Owada
Tetsuo Yamamoto
Ubari Hiroshi
Application Number:
JP2013551230A
Publication Date:
April 15, 2015
Filing Date:
December 21, 2012
Export Citation:
Assignee:
jfe Steel Corporation
International Classes:
C22C38/00; C21D9/46; C22C38/14; C22C38/60; C23C2/06; C23C2/40
Domestic Patent References:
| JP2005154809A | ||||
| JP2003321735A | ||||
| JP2000273577A | ||||
| JP2000212690A | ||||
| JP56169727A |
Foreign References:
| WO2011162412A1 |
Attorney, Agent or Firm:
Shigeru Inoue