Valve spring

US12338518B2 · kind B2 · utility

Assignees

• NIPPON STEEL CORPORATION · JP
• NIPPON STEEL SG WIRE CO., LTD. · JP

Inventors

• Shinya Teramoto · Tokyo, JP
• Yutaka Neishi · Tokyo, JP
• Michimasa Aono · Tokyo, JP
• Satoru Mineta · Tokyo, JP
• Shoichi Suzuki · Tokyo, JP
• Tatsuro Ochi · Muroran, JP

Key dates

• Filing date: Feb 19, 2021
• Grant date: Jun 24, 2025
• Expiry date: Apr 11, 2042

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/008
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

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/μm3, 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.