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:
Jun. 24, 2025
Filed:
Feb. 19, 2021
Nippon Steel Corporation, Tokyo, JP;
Nippon Steel SG Wire Co., Ltd., Tokyo, JP;
Shinya Teramoto, Tokyo, JP;
Yutaka Neishi, Tokyo, JP;
Michimasa Aono, Tokyo, JP;
Satoru Mineta, Tokyo, JP;
Shoichi Suzuki, Tokyo, JP;
Tatsuro Ochi, Tokyo, JP;
NIPPON STEEL CORPORATION, Tokyo, JP;
NIPPON STEEL SG WIRE CO., LTD., Tokyo, JP;
Abstract
A valve spring which has an excellent fatigue limit is provided. A chemical composition of the valve spring according to the present embodiment contains, in mass %, C: 0.50 to 0.80%, Si: 1.20 to less than 2.50%, Mn: 0.25 to 1.00%, P: 0.020% or less. S: 0.020% or less: Cr: 0.40 to 1.90%, V: 0.05 to 0.60%, Ca: 0.0001 to 0.0050%, and N: 0.0100% or less, with the balance being Fe and impurities. In the valve spring, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm, and a numerical proportion of Ca sulfides with respect to a total number of oxide-based inclusions and sulfide-based inclusions is 0.20% or less.