THIN STEEL SHEET AND METHOD FOR PRODUCING THIN STEEL SHEET

Japanese Patent JP3965886

B2

PROBLEM TO BE SOLVED: To provide a producing method capable of obtaining a high strength thin steel sheet excellent in workability including stretch-flanging properties, also uniform in mechanical properties and having various strength levels.
SOLUTION: This method for producing a high strength thin steel sheet has a stage in which a continuously cast slab having a C content of ≤0.8 wt.% is subjected to rough rolling, a stage in which the slab is subjected to finish rolling at ≥(Ar3 transformation point -20)°C, a stage in which the same is subjected to primary cooling to 500 to 800°C at >120°C/sec, a stage in which the same is let to cool for 1 to 30 sec, a stage in which the same is subjected to secondary cooling at ≥20°C/sec and a stage in which the same is coiled at ≤650°C. Moreover, it is possible that the continuously cast slab is heated to ≤1230°C without executing cooling to a room temperature, is thereafter subjected to rough rolling and is subjected to induction heating directly before or in the process of the finish rolling, within >0.1 to 1.0 sec after the finish rolling, the primary cooling is started, and the variation of the temperature in the width direction of the coil and in the longitudinal direction thereof after the rapid cooling (maximum value-minimum value) is controlled to ≤60°C.

Tadashi Inoue
Sadanori Imada
Keiyasu Kikuchi
Book house Yoichi

JP2000268896A

August 29, 2007

September 05, 2000

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jfe Steel Corporation

B21B1/00; C21D9/46; B21B3/00; C22C38/00; C22C38/14; (IPC1-7): C21D9/46; B21B1/00; B21B3/00; //C22C38/00

JP2002539330A
JP11100641A
JP10195588A
JP54065118A
JP11193443A
JP8176723A
JP4341523A
JP4337026A
JP4246127A

WO2000055381A1

Kenichiro Ochiai
Kazuhiro Mori

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