Abstract
In this report, authors researched changs of compositions and characteristics of molten cast iron treated with yttrium, holding at high temperature, and also investigated effects of remelting as J.J. Kanter and his collaborator described.
Several kinds of Fe-C-Si alloys were prepared as base alloy and after melting of each alloys added yttrium and imoculated by ferro-silicon. Test speecimens were castfrom these molten metal at reguler interval, keeping the required temperature. Authors tested to clarify the relation among gas content, cooling curve, chemical constituent and formed graphite characteristic.
Following results were obtained :
(1) Oxygen content increased a little by addition of yttrium and inoculation by addition of yttrium and inoculation, by ferro-silicon, nevertheless the graphite form changed from flake to spheroid.
(2) The residual content of yttrium and the extent of super cooling decreased according to the holding duration in molten state in spite of oxygen and sulpher content in original sample alloys, and the graphite form changed into quasiflake-euteeticflake from spheroid, therefore the graphite from is influenced by the residual content of yttrium and the extent of super cooling.
(3) Incase of comparatively rapid remelting at low temperature, using the electric furnace, the spheroidal graphite will be reappeared, but it will be imposible to produce the spheroidal graphite cast iron fron the cupola melt because of the increase of sulpher content.
