COLD-ROLLED STEEL SHEET WITH SUPERIOR SHAPE FIXABILITY AND MANUFACTURING METHOD THEREFOR

Title:

COLD-ROLLED STEEL SHEET WITH SUPERIOR SHAPE FIXABILITY AND MANUFACTURING METHOD THEREFOR

Document Type and Number:

WIPO Patent Application WO/2014/057519

Kind Code:

A1

Abstract:

Provided is a cold-rolled steel sheet with superior shape fixability and a manufacturing method therefor. On a steel raw material having a composition comprising, in mass%, C: 0.0010-0.0030%, Si: 0.05% or less, Mn: 0.1-0.5%, Ti: 0.021-0.060%, B: 0.0005-0.0050%, and containing B and C so that B/C is 0.5 or more, are performed: a hot-rolling process for finish-rolling with a finish-rolling completion temperature of 870-950°C and winding at a winding temperature of 450-630°C; a cold-rolling process with a cold-rolling reduction of 90% or less; and, after the cold-rolling process, an annealing process for heating to a soaking temperature in the range of 700-850°C at an average heating rate of 1-30°C/sec in the temperature range of 600°C and above, and, after holding for 30-200 sec, cooling to the temperature range of 600°C with a cooling rate averaging 3°C/sec or more. Obtained thereby is a cold-rolled steel sheet with superior shape fixability, the sheet having a structure wherein the main constituent is ferrite with a mean particle diameter of 10-30 µm and the proportional limit is 100 MPa or less.

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Inventors:

KIZU TARO (JP)
FUJITA KOICHIRO (JP)
KOGA HIDEHARU (JP)
MORIKAWA MASAHIDE (JP)
TAHARA KENJI (JP)

Application Number:

PCT/JP2012/006532

Publication Date:

April 17, 2014

Filing Date:

October 11, 2012

Export Citation:

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Assignee:

JFE STEEL CORP (JP)

International Classes:

C21D8/02; C22C38/14; C21D9/46; C22C38/32

Domestic Patent References:

WO2000006791A1

2000-02-10

Foreign References:

JP2012007196A	2012-01-12
JP2003055738A	2003-02-26
JPH073429A	1995-01-06
JPH0770650A	1995-03-14
JP2002066637A	2002-03-05

Other References: