| 摘要 |
PROBLEM TO BE SOLVED: To provide an austempering treated cast iron casting in which the formation of a decarburizing layer is prevented. SOLUTION: This is nondecarburized austempering treated cast iron in which a cast iron casting is held under soaking to an austenitizing temp. in a heat treating furnace having a furnace atmosphere in which the degree of vacuum is regulated to at least 10<-1> Torr, preferably, to 2×10<-2> Torr, is thereafter discharged from the heat treating furnace and is immediately subjected to isothermal transformation treatment to prevent the formation of a decarburizing layer on the surface layer part of the cast iron casting, and the method for producing the same is provided. The austenitizing temp. is regulated to 800 to 950 deg.C, and the isothermal transformation treatment is executed in a molten salt bath at 250 to 400 deg.C.
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