High-strength steel plate and manufacturing method thereof

A high-strength steel plate and manufacturing method technology, applied in the direction of manufacturing tools, coatings, furnace types, etc., can solve the problem that the processability is not comparable to that of polygonal ferrite, it is difficult to achieve high strength and processability at the same time, and the processability cannot be obtained And other problems, to achieve the effect of excellent extension flange, excellent ductility, and high use value
CN102149840AActive Publication Date: 2011-08-10JFE STEEL CORP
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
JFE STEEL CORP
Publication Date
2011-08-10

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Abstract

Disclosed is a high-strength steel plate having superior ductility and stretch flangeability and a tensile strength (TS) of 980 MPa or higher, and having 0.17-0.73% C, 3.0% or less Si, 0.5-3.0 or less Mn, 0.1% or less P, 0.07% S, 3.0% or less Al, 0.010% or less N, and 0.7% or more Si + Al, an area ratio of martensite of 10-90% with respect to the entire steel plate composition, a residual austenite amount of 5-50%, and an area ratio of bainitic ferrite in the upper bainite of 5% or less with respect to the entire steel plate composition. Twenty-five percent or more of the aforementioned martensite is tempered martensite, and the total of the area ratio of the aforementioned martensite with respect to the entire steel plate composition, the aforementioned residual austenite amount and the area ratio of the aforementioned bainitic ferrite in the upper bainite with respect to the entire steel plate composition is 65% or more. The area ratio of polygonal ferrite with respect to the entire steel plate composition is 10% or less (including 0%), and the average amount of C in the aforementioned residual austenite is 0.70% or more.
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Description

technical field

[0001] The present invention relates to a high-strength steel sheet having a tensile strength (TS) of 980 MPa or more and excellent formability, especially ductility and stretch-flangeability, used in industrial fields such as automobiles and electric equipment, and a method for producing the same. Background technique

[0002] In recent years, improving the fuel efficiency of automobiles has become an important issue from the viewpoint of global environmental protection. Therefore, studies are being actively conducted to reduce the weight of the vehicle body itself by reducing the thickness of vehicle body parts by increasing the strength of vehicle body materials.

[0003] Generally, in order to increase the strength of a steel sheet, it is necessary to increase the ratio of hard phases such as martensite and bainite to the entire structure of the steel sheet. However, increasing the strength of the steel sheet by increasing the proportion of the hard phas...

Claims

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