Invention Application
- Patent Title: COLD-ROLLED STEEL SHEET AND METHOD FOR PRODUCING THE SAME
- Patent Title (中): 冷轧钢板及其制造方法
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Application No.: US13258823Application Date: 2010-04-02
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Publication No.: US20120012231A1Publication Date: 2012-01-19
- Inventor: Toshio Murakami , Akira Ibano , Hideo Hata , Kenji Saito
- Applicant: Toshio Murakami , Akira Ibano , Hideo Hata , Kenji Saito
- Applicant Address: JP Kobe-shi
- Assignee: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
- Current Assignee: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
- Current Assignee Address: JP Kobe-shi
- Priority: JP2009-091297 20090403; JP2009-091298 20090403; JP2009-231680 20091005; JP2009-231681 20091005
- International Application: PCT/JP10/56096 WO 20100402
- Main IPC: C21D11/00
- IPC: C21D11/00 ; C22C38/04 ; C22C38/06 ; C22C38/16 ; C21D8/02 ; C22C38/12 ; C22C38/14 ; C22C38/18 ; C22C38/34 ; C22C38/38 ; C22C38/02 ; C22C38/08

Abstract:
A cold-rolled steel sheet of the present invention which has a composition containing, in terms of % by mass, C: 0.05-0.30%, Si: 3.0% or less (including 0%), Mn: 0.1-5.0%, P: 0.1% or less (including 0%), S: 0.010% or less (including 0%), and Al: 0.001-0.10%, and remainder being mainly iron, and which has a structure comprising, in terms of area ratio, 10-80% ferrite, less than 5% (including 0%) of the sum of retained austenite and martensite, and a hard phase as the remainder. The steel sheet gives a KAM value frequency distribution curve in which the relationship between the proportion of frequency having a KAM value ≦0.4, XKAM≦0.4°, and the area ratio of ferrite, Vα satisfies XKAM≦0.4°/Vα≧0.8 and the proportion of frequency having a KAM value in the range of 0.6-0.8, XKAM=0.6-0.8° is 10-20%. In the hard phase adjoining the ferrite, cementite, grains having an equivalent circle diameter of 0.1 μm or larger exist so that three or less such cementite grains are dispersed per μm2 of the hard phase. The steel sheet has improved balance between elongation and stretch flangeability and has better formability.
Public/Granted literature
- US08840738B2 Cold-rolled steel sheet and method for producing the same Public/Granted day:2014-09-23
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