STEEL SHEETS AND PROCESS FOR MANUFACTURING THE SAME

Title:

STEEL SHEETS AND PROCESS FOR MANUFACTURING THE SAME

Document Type and Number:

WIPO Patent Application WO/2009/078261

Kind Code:

A1

Abstract:

Provided are steel sheets which are soft and have excellent workability and excellent hardenability and a process for manufacturing the same. A steel sheet characterized by having a composition which contains by mass C: 0.3 to 0.7%, Si: 0.1% or below, Mn: 0.20% or below, P: 0.01% or below, S: 0.01% or below, Al: 0.05% or below, and N: 0.0050% or below with the balance being Fe and unavoidable impurities and a structure which comprises ferrite, graphite and cementite and in which the total volume fraction of ferrite, graphite and cementite accounts for at least 95% of the whole structure and the ratio of the volume of graphite to the total volume of graphite and cementite (degree of graphitization) is 5% or above, wherein the mean particle diameter of graphite and cementite is 5μm or below; and a steel sheet characterized by having the above composition and the above structure, wherein the sum of the volume fractions of graphite and cementite present in ferrite grains accounts for 15% or below of the total of graphite and cementite.

Inventors:

KARIYA NOBUSUKE (JP)
SETO KAZUHIRO (JP)

Application Number:

PCT/JP2008/071597

Publication Date:

June 25, 2009

Filing Date:

November 20, 2008

Export Citation:

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Assignee:

JFE STEEL CORP (JP)
KARIYA NOBUSUKE (JP)
SETO KAZUHIRO (JP)

International Classes:

C22C38/00; B21B3/00; C21D9/46; C22C38/06; C22C38/16

Foreign References:

JPH04311546A	1992-11-04
JPH0913142A	1997-01-14
JPH02107742A	1990-04-19
JPH04124216A	1992-04-24
JP2007039796A	2007-02-15
JPS6425946A	1989-01-27
JPH07258743A	1995-10-09
JPH04202744A	1992-07-23

Other References: