Study On Feeding Cored-wire Technology Of Compacted Graphite Iron Production

Compacted graphite iron is a material which is close to ductile iron in the respect of mechanical property, and close to gray cast iron in the respect of casting property. Substituting compacted graphite iron for ductile or alloy cast iron to manufacture the cylinder cap of diesel engine can improve the service performance and reduce production cost prominently. Compared with ductile iron, manufacturing compacted graphite iron is extremely difficult. Manufacturing compacted graphite iron by feeding cored-wire can avoid mass escaping and burning loss of vermicular agent, increase the absorptivity of vermicular agent in hot metal, prevent mass erupting momentarily of Mg steam, ensure adding safely of alloy, reduce the pollution of Mg light and soot to improve the production environment, control the addition amount of vermicular agent accurately, reduce temperature loss, control the account of remnant Mg accurately and acquire optimal vermicular effect steadily.In this paper, we study the relations between the vermicular graphite rate and the addition amount of cored-wire when we manufacture compacted graphite iron by feeding cored-wire, basing on the analysis and study of compacted graphite iron production practice. We use two kinds of cored-wire in the treatment process of compacted graphite experiment, one of which is vermicular graphite cored-wire containing 30% of Mg, and the other is RE-Si-Fe cored-wire containing 30% of RE. Both of them are of the same cored-wire diameter which is 10 millimeter.Conclusions drawn by experiments are that the vermicular graphite rate declines sharply, the graphite morphology is spherical when the amount of remnant Mg is more than 0.015%, and the graphite morphology is flaky when the amount of remnant Mg is less than 0.005%. We should pay more attention to the factors of the wire-feeding velocity, sulfur content of original hot metal, and the treatment process of compacted graphite temperature. The yield of vermicular agent depends on the wire-feeding velocity. The addition amount of vermicular agent and the vermicular graphite success rate depend on the sulfur content of original hot metal. The excessive sulfur content will lead to the addition amount of vermicular agent increasing, increasing the production cost. Keeping uniform processing temperature is very important for stabilizing the absorptivity of vermicular agent and for the corresponding casting quality.