SU834188A1 - Modifying composition - Google Patents

Description

(54) MODIFIED MIXTURE

The invention relates to foundry and can be used for the production of high-strength nodular cast iron. A modifier containing calcium, magnesium, iron, and silicon is known. When modifying pig iron with this modifier, the content of magnesium in does not vary within + 0.02% without taking into account the varying degree of assimilation of the modifier metals. This leads to the synchronization of the mechanical and operational properties of cast iron. The closest to the proposed technical essence and the achieved effect is the modifying mixture C2, containing, wt.%: Magnesium 5-15 Ferrosilicon85-95 When modifying this effect, a significant pyroelectric effect and smoke emission occurs. "Magnesium uptake is 20-50%. In cast iron (especially cupola melting), so-called black spots are found at a ligature flow rate of 3%. The reason for the occurrence of black spots is the appearance of sulfides and oxides of magnesium, which, due to their size, do not have time to coagulate and emerge into a donkey. Castings with black spots are counted as defects and cannot be further processed. The purpose of the invention is to increase the absorption of magnesium and the production of nodular cast iron. This goal is achieved by the fact that the modifying mixture containing magnesium and ferrosilicon additionally contains ferrochromic slag in the following ratio, wt.% Magnesium 3-30 Ferrosilicon 40-96 Ferrochromic slag 1-30 its ability to refine cast iron by bonding sulfur into a host of coagulable non-metallic compounds that float into the slag, thereby releasing magnesium to spheroidize graphite. Ferrochromic slag delays. And it regulates the process of interaction between magnesium and cast iron and thereby increases the degree of absorption of magnesium. The mechanism of interaction of liquid iron with a modified mixture is to create a layer of porous flux.

through which magnesium evaporates is evenly distributed throughout the entire volume of molten iron. The modifying mixture is at the bottom of the bucket in the initial period of modification and then is uniformly consumed during the entire modification process, due to the high dispersion of cMecfj, as well as the non-wettability of the mixture with liquid iron.

The modifying mixture is made by mechanically mixing the components under the usual conditions.

Example. In order to determine the optimal composition of the proposed modifying mixture, the degree of assimilation of magnesium by the cast iron and the presence of black spots depending on the different content of the ingredients of the proposed mixture are examined.

Cast iron is produced by constant technology in an IHL induction furnace.

3.096.0

1085

2070

3040

595

1090

1585

102. Chemical composition of the initial cast iron is as follows, wt.%: C 3.20-3.58 Si 1.65-2.20 Mp 0.60-0.68; S 0,120, 14. The metal is released at a constant temperature equal to that it is made into casting heated up to 700 ° C ladles with a capacity of 30 kg, from which test forms are then poured to obtain samples for structural and chemical analyzes.

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Modification of cast iron production sandwich process.

The results of the structural and chemical analyzes of the test samples are given in Table. 1 and 2..

As can be seen from the above data, the modification of pig iron with the proposed modifying mixture increases the degree of magnesium absorption by 1.5–2 times, black spots are not detected, graphite has a spherical shape.

Table

1.0 5

Claims (2)

10 30 783418 Claims of the invention Modifying the mixture containing magnesium and ferrosilicon, so that, in order to increase the absorption of magnesium and eliminate casting, it additionally contains Ferrochrome slag with the following ratio of components, weight. %: 8 8. Magnesium 3-30 Ferrosilicon40-96 Ferrochrome slag 1-30 Sources of information taken into account in examination 1, Foundry, 1973, No. 4, p. 40. 2. Vashchenko KI and others. Magnesium cast iron. Kiev, I960, with. eight.