Damper spring
AssigneesNippon Steel Corporation, Nippon Steel Sg Wire Co., Ltd.
InventorsShinya Teramoto, Yutaka Neishi, Michimasa Aono, Shoichi Suzuki, Tatsuro Ochi
Life of this patent
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Abstract
A damper spring which has an excellent fatigue limit is provided. A chemical composition of the damper 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%, and N: 0.0100% or less, with the balance being Fe and impurities. In the damper spring, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm3.
Claims4
A damper spring, wherein:
- when a wire diameter is defined as d (mm), a chemical composition at a d/4 depth position from a surface 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%,
- N:
- 0.0100% or less,
- Mo:
- 0 to 0.50%,
- Nb:
- 0 to 0.050%,
- W:
- 0 to 0.60%,
- Ni:
- 0 to 0.500%,
- Co:
- 0 to 0.30%,
- B:
- 0 to 0.0050%,
- Cu:
- 0 to 0.050%,
- Al:
- 0 to 0.0050%, and
- Ti:
- 0 to 0.050%,
- with the balance being Fe and impurities,
- and wherein:
- in a microstructure of the damper spring, an area fraction of martensite is 90.0% or more, and
- a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm3.
Dependencies are inferred from the claim text.