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US 7,597,768 B2Granted
Steel wire for hard drawn spring excellent in fatigue strength and resistance to settling, and hard drawn spring and method of making thereof
AssigneesKabushiki Kaisha Kobe Seiko Sho, Suncall Corporation
InventorsSumie Suda, Nobuhiko Ibaraki, Nao Yoshihara, Shigetsugu Yoshida, Koji Harada
Life of this patent
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Abstract
Disclosed is a hard-drawn spring which exhibits fatigue strength and sag resistance equal or superior to springs produced using an oil-tempered wire. The hard-drawn spring is produced using a steel wire containing 0.5 to 0.7 mass % of C, 1.0 to 1.95 mass % of Si, 0.5 to 1.5 mass % of Mn and 0.5 to 1.5 mass % of Cr, with the balance being Fe and inevitable impurities. In the steel wire, the number of carbides having circle-equivalent diameters of 0.1 μm or more is 5 particles/100 μm2 or less.
Claims18
A hard-drawn steel wire comprising:
- C:
- 0.5-0.68 mass % (hereinafter, referred to as %),
- Si:
- 1.2-1.95%,
- Mn:
- 0.5-1.5%,
- Cr:
- 0.62-1.5%,
- Fe and inevitable impurities, wherein
- said wire consists of at least one selected from the group consisting of ferrite and pearlite, and
- said wire further comprises 5 particles/100 μm2 or less of carbides wherein the circle-equivalent diameters of the carbides are more than 0.1 μm.
8 more elements
Dependencies are inferred from the claim text.