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AssigneeNippon Steel Corporation
InventorsManabu Kubota, Masayuki Hashimura
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The present invention provides high strength spring and high strength spring steel wire superior in corrosion fatigue characteristics and methods of production of the same, that is, a high strength spring steel wire and high strength spring containing, by mass %, C: 0.35 to 0.50%, Si: 1.00 to 3.00%, and Mn: 0.10 to 2.00%, restricting P to 0.015% or less and S to 0.015% or less, having a balance of Fe and unavoidable impurities, and, when raising the temperature in the range from 50° C. to 600° C. by 0.25° C./s and measuring the differential scanning calories, having the only peak of the exothermic reaction present at 450° C. or more. A method of production of high strength spring characterized by tempering under conditions where the tempering temperature T[K], tempering time t[s], and content Si % [mass %] of Si satisfy the following: 16000≦(T−40×[Si %])×(31.7+log t)≦23000.
A high strength spring steel wire characterized by containing, by mass %,
A high strength spring characterized by containing, by mass %,
A method of production of high strength spring steel wire characterized by heating steel wire comprised of the ingredients as set forth in claim 1 to 850 to 1000° C., quenching it, then tempering it under conditions where the tempering temperature T[K], tempering time t[s], and content Si % [mass %] of Si satisfy the following formula 1:
A method of production of a high strength spring characterized by heating steel wire comprised of the ingredients as set forth in claim 5 to 850 to 1000° C., hot forming it into a spring shape, then quenching it, then tempering it under conditions where the tempering temperature T[K], tempering time t[s], and content Si % [mass %] of Si satisfy the following formula 1:
Dependencies are inferred from the claim text.