含硫鋳鉄の黒鉛球状化に及ぼすMg合金の効果並びにMg処理した鋳鉄中のMgの挙動について

Abstract

The good graphite nodulizing effect has been shown in the complex alloys containing 8∼15%Mg. Graphite forms in cast iron containing 0.05∼0.3%S have been investigated by using 15%Mg-Ni-Cu-Si alloy and 7.93%Mg-Ni-Fe-Si alloy, and it has been shown that the latter alloy has the better alloying efficiency of magnesium than the former alloy.“Sulphur-print” both before and after the magnesium treatment has been examined, and it has been found that the print of spherulitic graphite iron shows reddish-brown colouring in spite of the strong desulphurisation effect due to the addition of magnesium, though the print before the magnesium treatment is coloured blackish-brown or light brown.The special colouring of the print in the spherulitic graphite iron has been confirmed to be caused by the emission of hydrocarbon, and we call this print “Hydrocarbon-print”.The existence of magnesium-carbide or the like in spherulitic graphite iron could be conjectured from the above experimental result. The amount of magnesium-carbide or the like decreases in both ledeburitic iron resulted from rapid cooling of magnesium-treated iron and ferritic iron obtained by annealing of spherulitic graphite iron.It may be probable that the magnesium-carbide or the like exists not only as the exogenous nucleus in the center or spherulitic graphite which professor A. de Sy has mentioned in his theory, but also in the combined state in the solid of the spherulitic graphite or in the adsorped state on the surface of the spherulitic graphite.