| 摘要 |
PURPOSE:To improve heat resistance and fatigue strength, by providing a composition in which C, Si, Mn, and Cr are used as essential components and V, Mo, Nb, and Ta are selected and combined by a specific quantity and also controlling the size of inclusions, the maximum residual compressive stress value in the vicinity of surface, and surface roughness. CONSTITUTION:A spring has a composition consisting of, by weight, 0.6-0.7% C, 1.2-1.6% Si, 0.5-0.8% Mn, 0.5-0.8% Cr, 0.05-0.2%, in total, of one or more elements among V, Mo, Nb, and Ta, and the balance Fe with impurities. In this composition, the maximum size of nonmetallic inclusions is controlled to <=15mum to reduce deterioration in fatigue strength. Further, shot peening, etc., are applied, by which the maximum residual compressive stress in the vicinity of the surface of the spring is provided within the range of 85-110kgf/ mm<2> and surface roughness is controlled to <=Rmax15mum.
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