Alloys or metallic compositions – Ferrous – Chromium containing – but less than 9 percent
Reexamination Certificate
2011-08-30
2011-08-30
King, Roy (Department: 1733)
Alloys or metallic compositions
Ferrous
Chromium containing, but less than 9 percent
C148S318000, C148S333000
Reexamination Certificate
active
08007716
ABSTRACT:
A steel wire has tempered martensite, comprises, as essential components, by mass, C: 0.53 to 0.68%; Si: 1.2 to 2.5%; Mn: 0.2 to 1.5%; Cr: 1.4 to 2.5%; Al: 0.05% or less; further comprises, as a selective component, Ni: 0.4% or less; V: 0.4% or less; Mo: 0.05 to 0.5%; or Nb: 0.05 to 0.5%; and further comprises remainder essentially consisting of Fe and inevitable impurities, wherein the grain size number of prior austenite is 11.0 or larger, and the proof stress ratio (σ0.2/σB), namely, a ratio of 0.2% proof stress (σ0.2) to tensile strength (σB) is 0.85 or lower. Satisfying the above requirements makes it possible to produce a steel wire for high-strength spring excellent both in workability (cold workability), and in sag resistance and fatigue properties.
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Fujiwara Tadayoshi
Ibaraki Nobuhiko
Jinbo Tetsuo
Suda Sumie
Takamura Noritoshi
Fogarty Caitlin
Kabushiki Kaisha Kobe Seiko Sho
King Roy
NHK Spring Co. Ltd.
Oblon, Spivak McClelland, Maier & Neustadt, L.L.P.
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