| 摘要 |
PROBLEM TO BE SOLVED: To provide a producing method of a spheroidal graphite cast iron casting parts having the wear resistance from the surface layer part to the inner part without developing the decarburized layer on the surface layer part. SOLUTION: The producing method of the non-decarburized and wear resistant spheroidal graphite cast iron casting product, is the one, in which after holding and soaking the spheroidal graphite cast iron casting parts 5 at the austenitic temp. range of 800-950 deg.C for 0.3-5hr in a heat treatment furnace 1 having the vacuum atmosphere or in the heat treatment furnace 1 having the reduced pressure RX gas atmosphere, this casting parts is taken out from the heat treatment furnace 1 and dipped into salt bath 6 at the cooling speed which does not develop pearlitic structure, and successively, an isothermal transformation treatment is applied in the salt bath 6 and therefore, the air-cooling is executed. The most desirable vacuum atmosphere is at >=2×10<-2> Torr and the most desirable time from taking out from the heat treatment furnace 1 till dipping into the salt bath 6 is within 45sec and the most desirable isothermal transformation treating temp. is 250-400 deg.C.
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