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The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Patent No.:

US 8845825 B1

PDFFull Text
Date of Patent:
Sep. 30, 2014

Filed:

Mar. 29, 2007

High strength spring-use heat treated steel

Applicants:

Masayuki Hashimura, Muroran, JP;

Tatsuro Ochi, Muroran, JP;

Takayuki Kisu, Muroran, JP;

Hiroshi Hagiwara, Tokyo, JP;

Inventors:

Masayuki Hashimura, Muroran, JP;

Tatsuro Ochi, Muroran, JP;

Takayuki Kisu, Muroran, JP;

Hiroshi Hagiwara, Tokyo, JP;

Assignee:

Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;

Attorney:

Kenyon & Kenyon LLP

Primary Examiner:

Yoshitoshi Takeuchi

Int. Cl.
CPC ...
C22C 38/08 (2006.01); C23C 8/20 (2006.01); C23C 8/24 (2006.01); C23C 8/00 (2006.01); C23C 8/26 (2006.01); C23C 8/50 (2006.01); C23C 22/00 (2006.01); C22C 38/16 (2006.01); C22C 33/00 (2006.01); C22C 38/60 (2006.01); C22C 38/02 (2006.01); C22C 38/18 (2006.01); C21D 9/52 (2006.01); C22C 38/34 (2006.01); C22C 38/04 (2006.01); C22C 38/00 (2006.01);
U.S. Cl.
CPC ...
C21D 9/52 (2013.01); C22C 38/02 (2013.01); C22C 38/18 (2013.01); C22C 38/34 (2013.01); C22C 38/04 (2013.01); C22C 38/001 (2013.01); C22C 38/60 (2013.01);
Abstract

The present invention provides spring use heat treated steel which is cold coiled, can achieve both sufficient atmospheric strength and coilability, has a tensile strength of 2000 MPa or more, and can improve the performance as a spring by heat treatment after spring fabrication, that is, high strength spring-use heat treated steel characterized by containing, by mass %, C: 0.45 to 0.9%, Si: 1.7 to 3.0%, and Mn: 0.1 to 2.0%, restricting N: to 0.007% or less, having a balance of Fe and unavoidable impurities, and satisfying, in terms of the analyzed value of the extracted residue after heat treatment, [amount of Fe in residue on 0.2 μm filter/[steel electrolysis amount]×100≦1.1.

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