PURPOSE: To promote graphite spheroidization and prevent the occurrence of cracking by limiting the specific components of spheroidal graphite cast iron and adjusting the rate of solidification after pouring in enclosing cooling piping with spheroidal graphite cast iron.
CONSTITUTION: CaC2 is added as a desulfurizing agent to the molten metal of cast iron and the molten metal is stirred while N2 gas is being blown, whereby it is subjected to desulfurization. Next, Fe-Si-Mg alloy is used as spheroidizing material to make the spheroidal graphite cast iron whose specific components in the composition are S; 0.005% or less, P; 0.07% or less and Ti; 0.03% or less based on weight. Thence, casting is done and N2 gas is fed into the cooling pipings 2, 2' which are enclosed in a cooling stave body 1, whereby the adjustment of the rate of cooling is accomplished so that the central part of the thickness of the cooling stave 1 after the pouring completes solidifying within 80 minutes. Here, the limitation of the specific component amounts and solidification time is necessary for achieving the graphite spheroidization of the thickness central part.
GEMA TERUO
HIGUCHI MASAAKI
SUGAWARA TSUNENORI
YANO TAKESHI
NIPPON CASTING CO LTD
| JPS5083202A | 1975-07-05 |