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Title:
MANUFACTURE OF SPRING WITH HIGH FATIGUE STRENGTH AND STEEL WIRE FOR SPRING FOR USE THEREIN
Document Type and Number:
Japanese Patent JPH0257637
Kind Code:
A
Abstract:

PURPOSE: To manufacture a spring having high fatigue strength by subjecting a steel with a specific composition to austenitizing treatment, to heating treatment under specific conditions, and to cooling and further subjecting the above steel to cold spring forming into the prescribed shape and then to strain age hardening treatment at a specific temp.

CONSTITUTION: A steel which has a composition consisting of, by weight, 0.3-1.3% C, 0.8-2.5% Si, 0.5-2.0% Mn, 0.5-2.0% Cr, and the balance Fe with inevitable impurities and containing, if necessary, one or ≥2 kinds among 0.1-0.5% Mo, 0.05-0.5% V, 0.002-0.5% Ti, 0.005-0.2% Nb, 0.0003-0.01% B, 0.1-2.0% Cu, 0.01-0.1% Al, and 0.01-0.05% N is subjected to austenitizing treatment. Subsequently, the above steel is held at 250-500°C for 3sec-30min, air-cooled or rapidly cooled, and subjected to cold spring forming into the prescribed shape and then to strain age hardening treatment at 200-450°C. By this method, the cold forming coiled spring having ≥ about 200kgf/mm2 strength and high fatigue strength can be obtained.


Inventors:
TARUI TOSHIZO
ASANO YOSHIYUKI
SUZUKI SHINICHI
Application Number:
JP1988000207337
Publication Date:
February 27, 1990
Filing Date:
August 23, 1988
Export Citation:
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Assignee:
NIPPON STEEL CORP
International Classes:
C21D9/02; C21D9/52; C22C38/00; C22C38/32; (IPC1-7): C21D9/02; C21D9/52; C22C38/00; C22C38/32