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.:
Date of Patent:
Feb. 12, 2019
Filed:
Apr. 22, 2015
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Masayuki Hashimura, Kisarazu, JP;
Junya Yamamoto, Nakano-ku, JP;
Kazumi Mizukami, Futtsu, JP;
Naotsugu Yoshida, Kimitsu, JP;
Masafumi Miyazaki, Kisarazu, JP;
Kenichiro Miyamoto, Kitakyushu, JP;
NIPPON STEEL & SUMITOMO METAL CORPORATION, Tokyo, JP;
Abstract
A spring steel according to the present embodiment has a chemical composition consisting of, in mass %, C: 0.4 to 0.7%, Si: 1.1 to 3.0%, Mn: 0.3 to 1.5%, P: 0.03% or less, S: 0.05% or less, Al: 0.01 to 0.05%, rare earth metal: 0.0001 to 0.002%, N: 0.015%, O or less: 0.0030% or less, Ti: 0.02 to 0.1%, with the balance being Fe and impurities. In the spring steel, the number of oxide inclusions having an equivalent circular diameter of equal to or greater than 5 μm is equal to or less than 0.2/mm, the oxide inclusions each being one of an Al-based oxide, a complex oxide containing REM, O and Al, and a complex oxysulfide containing REM, O, S, and Al. Further, a maximum value among equivalent circular diameters of the oxide inclusions is equal to or less than 40 μm.