| 摘要 |
PURPOSE:To obtain the titled member with superior fatigue strength, wear resistance, etc. by forming a differential gear case and an austempered ring gear having a bainite structure in a body from a spheroidal graphite cast iron material contg. C, Si, Mn, P, S, Cu or Sn, Mo and Mg. CONSTITUTION:A spheroidal graphite cast iron material consisting of, by weight, 2.6-4.0% C, 1.5-3.5% Si, 0.1-1.0% Mn, <=0.15% P, <=0.03% S, 0.3-1.5% Cu or 0.03-1.6% Sn, 0.03-0.1% Mo, 0.025-0.1% Mg and the balance Fe is prepared. After refining the structure of the material, the part of the material for forming a ring gear is notched, and the ring gear part is austempered by local quenching. The austemepered ring gear and a differential gear case are formed in a body to obtain the desired differential member for a vehicle.
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