SU1388433A1 - Method of producing grey modified cast iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the smelting of iron in induction furnaces. The purpose of the invention is to reduce specific energy consumption. The proposed method includes smelting iron in an induction furnace, thermal processing of the melt, adding pulverized potash to the melt in an amount of 0.003-0.005% by weight of the melt, holding the melt, adding a mixture of fine graphite electrode electrode boil and blast furnace dust at a ratio between them (1-4 -): 1 and the mixture consumption is 0.05-0.25% by weight of the melt and the silicon-containing modifier is introduced into the ladle when the melt is released from the furnace. Processing the melt with potash and a mixture of electrode bo and top dump can reduce the specific energy consumption by 5-50 kW / h per ton of iron. 1 tab. c & (L

Description

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The invention relates to metallurgy, in particular to the development of methods for smelting iron in induction furnaces.

The purpose of the invention is to reduce specific energy consumption.

Example. The method is carried out using cast iron with carbon equivalent CE 3.70-3.75%, built in an electric induction furnace on a mixture of steel scrap with additives of ferroalloys and carburizer for finishing up to a given chemical composition.

The molten iron in the furnace is heated to 1490 + 10 ° C, then cooled down to 1400 ° C and at this temperature dusty potash is introduced in an amount of 0.004%

tensile strength and modifier consumption).

The addition of pshevidny potash in the amount of 0.003-0.005% by weight of the liquid metal provides a weakening of chemical bonds in the melt between its atoms and leads to an increase in the oscillations of the amplitudes of the atoms, especially

the surface of the melt, which ensures rapid and effective absorption of subsequent additives over time. At. the introduction of powdered potash in the amount of cBbmie of 0.005% in the iron increases the carbon and silicon content, which leads to instability of its chemical composition and decrease in mechanical properties. With the addition of pshevidny potash in an amount of less than 0.003% is not

from the mass of the liquid metal and after 0.5–20, the effect of precautionary

1 min is introduced into the melt a mixture of fine graphite electrode bo and flue dust with their ratio (1-4): 1 and a total amount of 0.05-0.25% by weight of the liquid metal, then after 2 minutes of exposure the melt is discharged into the pouring ladle. When the ladle is filled, it is squatted by 20–25% evenly over the next period of the addition of the liquid metal of ferrosilicon FS75 in it in the amount of 0.15–0.20% by weight of the metal collected in the ladle.

For comparison, modified gray cast iron was obtained in a known manner. The evaluation of the modifying effect and the properties of modified cast irons obtained by the proposed and known methods is carried out by bleaching the technological sample with a size of 100 ± 50 mm poured into a mold with a metal plate and tensile strength at stretching Cs of specimens made from cylindrical billets 30 mm and d5 properties of cast iron. When additives are small-long 340 mm, poured into a rod form.

The table presents the results of tests of modified gray cast iron obtained under different processing conditions.

From the data in the table it can be seen that the proposed method for producing modified gray iron compared with the known method provides a reduction in electricity consumption of up to 5-50 kW / h per 1 ton of pig iron produced while maintaining the level of other characteristics (chill,

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dispersed graphite of electrode boil and flue dust in a total amount of less than 0.05%. The effect of pretreatment of cast iron is not achieved due to the formation of an artificial germinal phase in insufficient quantity. With the introduction of fine graphite electrode boil and flue dust in a ratio of less than 1, the fragility of modified cast iron is greater and the appearance of free cementite in the microstructure. With the introduction of a fine graphite electrode bo and cols5

0

five

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the processing of cast iron, which leads to insufficiently rapid absorption of subsequent additives and an increase in the brittleness of cast iron. The addition of fine graphite electrode bo and top stock in a total amount of 0.05 - 0.25% of the mass of liquid iron ensures the formation of the required amount of artificial germinal phase in the melt, which increases the tendency of the iron to graphitization and modification. At the same time, the amount of injected graphite and top stock depends on the content of steel scrap in the charge; in particular, the more the scrap contains in the charge, the higher the total amount of injected graphite and top stock should be and the smaller their ratio.

With the introduction of a total amount of fine graphite of electrode bo and flue dust over 0.25% in the iron, the carbon content increases, which negatively affects

properties of cast iron. At additives finely -

dispersed graphite of electrode boil and flue dust in a total amount of less than 0.05%. The effect of pretreatment of cast iron is not achieved due to the formation of an artificial germinal phase in insufficient quantity. With the introduction of fine graphite electrode boil and flue dust in a ratio of less than 1, the fragility of modified cast iron is greater and the appearance of free cementite in the microstructure. With the introduction of fine graphite electrode bo and top furnace in relation to more than 4, npo4 iocTb of cast iron is reduced due to the increased degree of graphitization and deterioration, ”or the shape of the graphite inclusions and its distribution.

Claims (1)

The invention method for producing gray modified cast iron, including smelting iron in an induction furnace, thermal processing, the release of the melt - and an additive to the molten iron in the silicon-containing modifier bucket, from the proposed options Characterized by the fact that, in order to reduce the specific energy consumption, pulverized potash in an amount of 0.003-0.005% by weight of the melt is additionally added to the silicon-containing alloy, and then after aging, a mixture of fine graphite electrode boil and ash dust is placed in the melt when the ratio between them is equal to (1-4):: 1 and the mixture consumption is 0.05-0.25% by weight of the melt.