Shaped Steel Excellent in Fire Resistance and Producing Method Therefor

a technology of shaped steel and fire resistance, which is applied in the field of new shaped steel, can solve the problems of lack of uniform microstructure lack of uniform mechanical properties of the section of steel, and low productivity, and achieve excellent mechanical properties and excellent strength
US20080302453A1Inactive Publication Date: 2008-12-11NIPPON STEEL CORP
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Patent Information

Authority / Receiving Office
US ¡ United States
Patent Type
Applications(United States)
Current Assignee / Owner
NIPPON STEEL CORP
Publication Date
2008-12-11
Estimated Expiration
Not applicable ¡ inactive patent

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Abstract

A shaped steel, such as H-shaped steel, excellent in fire resistance, where a flange portion has 50% or more of a ratio of strength, 80% or less of yield ratio, and 100 J or more of impact strength of Charpy impact test at 0° C., wherein the ratio of strength=(proof stress of 0.2% at 600° C.) / (yield strength at room temperature), and a producing method thereof are provided. The shaped steel comprises in mass percent (%): C: 0.03-0.15; Mo: 0.1-0.6; V≦0.35; and N: 0.002-0.012, and the balance being iron and residual impurities, wherein (x) a mol fraction of precipitate of alloy carbides and alloy carbonitrides at 600° C. is 0.3% or more, and (y) the ratio of the mol fraction of precipitate of alloy carbides and alloy carbonitrides at 300° C. to the mol fraction of precipitate of alloy carbides and alloy carbonitrides at 600° C. is 2.0 or less.
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Description

[0001] This application claims priority to Japanese patent application No. 2004-220337, filed in Japan on Jul. 28, 2004, Japanese patent application No. 2004-220454, filed in Japan on Jul. 28, 2004, and Japanese patent application No. 2005-207185, filed in Japan on Jul. 15, 2005, the entire contents of which are herein incorporated by reference.

[0002] The present invention relates to a novel shaped steel, such as H-shaped steel, I-shaped steel, angle steel, channel steel, etc., which is used as a building construction material, with a low yield ratio and having excellence in toughness and fire resistance, and a method for producing the same.

[0003] The legislation about “new code to design fire-resistant structures” was enacted on March, 1987 in Japan. After that, fire-resistant steel materials, which secure high strength at high temperature without or with less fire-resistant wrapping, have been desired.

[0004] As for shaped steels, according to the trend, a lot of technologies for secur...

Claims

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