球状黒鉛鋳鉄溶湯における生型砂のドロス化

抄録

  When spheroidal graphite cast iron is produced by green sand molding, sand inclusion defects are often found in the mixture of green sand and dross. In order to clarify their formation mechanism, casting experiments were carried out as follows : A comparison of inclusion defects between spheroidal graphite cast iron (which contains both Mg and Mn), flake graphite cast iron (which does not contain Mg and Mn), and flake graphite cast iron (which contains only Mn) was carried out by casting in a green sand mold. While pouring the molten metal, some loose green sand was added to the stream. A combination of Mg dross and green sand was formed in the case of spheroidal graphite cast iron, a combination of Mn-containing slag and green sand in the case of flake graphite cast iron containing Mn, and a combination of Fe-containing slag and green sand in the case of flake graphite cast iron without Mn. Thus, sand inclusion defects were formed in all cases. It was found that the dross and slag, which are oxides, were formed in the order MgO, MnO, and FeO. Na in the green sand was also seen to vaporize and adhere to voids in the sand inclusion defects.