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. 11, 2024
Filed:
Oct. 15, 2020
Nippon Steel Corporation, Tokyo, JP;
Nhk Spring Co., Ltd., Yokohama, JP;
Nippon Steel SG Wire Co., Ltd., Tokyo, JP;
Shinya Teramoto, Tokyo, JP;
Yutaka Neishi, Tokyo, JP;
Michimasa Aono, Tokyo, JP;
Shuji Kozawa, Tokyo, JP;
Fumio Takahashi, Yokohama, JP;
Shigekazu Nishimoto, Yokohama, JP;
Mitsuhiro Kondo, Yokohama, JP;
Tatsuro Ochi, Tokyo, JP;
Shoichi Suzuki, Tokyo, JP;
NIPPON STEEL CORPORATION, Tokyo, JP;
NHK SPRING CO., LTD., Kanagawa, JP;
NIPPON STEEL SG WIRE CO., LTD., Tokyo, JP;
Abstract
A valve spring includes a nitrided layer, and a core portion that is further inward than the nitrided layer. A chemical composition of the core portion consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr: 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Ca: 0.0001 to 0.0050%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, and N: 0.0070% or less, with the balance being Fe and impurities. In the core portion, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 per μm, and in the core portion, 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.