PRODUCTION OF CV GRAPHITE CAST IRON

摘要

PURPOSE:To control the amt. of Mg and to obtain easily a CV graphite cast iron having a good characteristic by selecting the amt. of the alloys to be added and the elapsed time in the stage of adding an Fe-Si-Mg alloy to a molten base metal having a prescribed compsn. then adding Fe-Si thereto. CONSTITUTION:Silicon steel plate scrap, low-S carburized material and Fe-Si are melted in the remaining molten metal corresponding to FC15 and the molten metal is then desulfurized by using a low frequency induction furnace by which the molten base metal for a spheroidal graphite cast iron consisting of 3.6- 3.9wt% T.C, 1.4-1.6% Si, 0.3-0.4% Mn, 0.044-0.057% P, 0.02-0.03% S and the balance Fe is produced. An Fe-Si-Mg alloy is added at 0.4-0.75% to such molten base metal, then Fe-Si is brought into contact therewith. The lapsed time after the inoculation is selected from the region II of the figure showing the relation between the amt. of the alloy to be added and the elapsed time. The amt. of the remaining Mg and S after the alloy treatment is selected in the range II between the straight lines A and B of the figure showing the relation between the amt. of the remaining Mg and the amt. of the remaining S. The control range of the remaining Mg is thus widened and the appearance of CV graphite is quantitatively known.