SU1079684A1 - Mix for modifying grey cast iron - Google Patents

Abstract

MIXTURE FOR MODIFICATION OF GRAY CASTLE, containing barium, silicocalcium, graphite and ferrosilicon, characterized in that, in order to increase the duration (live) of the mixture, prevent chipping and reduction of toxicity and fire-hazard when used for complex castings. , it contains barium in the form of a silicobarium and in addition silicon carbide and ferrotitanium with the following ratio of components, ma c. %:. : Graphite32-38 Silicocalcium 5-9 Silicobarium 6-10 Silicon Carbide 35-40 Ferrotitanium 0.1-1.0 Ferrosilicon Else

Description

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The invention relates to metals, in particular to foundry, and can be used to modify gray iron. The known mixture for modifying thin-walled castings ij of the following composition, wt. %: 30-55 Silikokaltsii. 5-25 Silikomishmetall 10-30 Else Iron However, a high coke content can lead to an increase in the sulfur content in the iron. In addition, a high silicocalcium content makes the mixture unsuitable for cupola iron, which is characterized by a relatively low metal temperature at high temperatures. The known mixture for modifying cast iron 2J of the following composition, weight,% g the content of alkaline or alkaline-earth metal, which hampers the introduction into the liquid metal, due to its low specific weight and high chemical activity {high carbon loss. The use of such a mixture does not allow to obtain stable results of the modification. ; -. Also known mixture for modifying gray cast iron on the trail of composition, weight,%: Technical boric acid Silicocalcium Silicobarium Graphite Else However, the high content in the mixture of calcine and silicobar impedes the absorption of the mixture with liquid iron — pr. temperatures less due to high tendency to slagging, which excludes the possibility of using such a mixture for cupola iron and electric furnace, provided it accumulates in the mixer. The closest in composition and to the inhibited effect to the proposed mixture for modifying the sludge composition, wt. %:. Graphite 5-10 Cryolite 15-45 Silicocalcium Ferrosilicon Else The use of metallic barium to increase the vitality in this mixture makes it unstable (it does not ensure the absence of chill in the castings during the entire casting time and is fire and explosion hazardous, since barium, being a highly active element, is easily oxidized. In addition, barium is a toxic element. The cryolite that is part of this mixture can decompose with the absorption of toxic hydrofluoric acid. The purpose of the invention is to increase the duration of the effect of vitality. If you use chucking and reduce toxicity and fire hazard when using complex configurations for gray iron castings, the goal is to find that the barium in the form of silicon barium, silicocalcium, ferrosilicon graphite, for modifying gray cast iron, contains silicium barium silicide and additionally silicon carbide, and silicon silicide. the following ratio of components, may.%: Graphite Silicocalcium 6-10 Silicobarium 35-40 Silicon Carbide 0.1-1.0 Ferrotitanium Ferrosilicon Rest Dissociation of silicon carbide into carbon and silicon is exists the formation of active graphite nuclei in the cast iron melt, and thereby reduce chill depth. The replacement of metal with barium by silicobarium allows the elimination of fire and explosion hazards and the toxicity of the mixture, in addition, to ensure the stability of the results in the separation from the beginning to the end of the casting, i.e. increase the duration of the modifying action | Mixtures. With the addition of less than 6.0% of silicobari to the mixture, the duration of action of the modifier is significantly reduced, and with the introduction of a silicobar of more than 10%, an explosive and fire hazard appears when using wood. The addition of titanium to all ferrotitanium or other titanium-containing compounds eliminates withdrawal, and the influence of a constant impurity of pig iron — nitrogen, thereby also reduces the tendency to bleaching and

it allows wider use in furnaces for the production of cast iron from secondary raw materials.

The introduction of more than 1.0% of ferrotitanium into the mixture is accompanied by a change in the nature of its effect — instead of a graph-forming agent, it becomes a carbide stabilizing element. With the introduction of ferrotitanium less than 0.1% - its graphitizing ability does not appear.

When the silicocalcium content is less than 5.0%, the desulphurisation and graphitizing ability of the mixture is significantly reduced, and if the silicocalc content is more than 9.0%, the tendency is to slag the mixture during the modification and thereby reduce the effectiveness of its effect.

Grinding ratios of graphite to silicon carbide content are primarily determined by obtaining a satisfactory fluidity of the mixture when introduced through a funnel into liquid iron. It is established that this ratio should be close to unity. The lower limits on the content of graphite 32% and silicon carbide 35% provide high fluidity and modifying ability of the mixture with a relatively low consumption (0.15-0.2% by weight of the liquid metal). A graphite content of more than 38% and silicon carbide more than 40% can lead to an uneven distribution of graphite in cast iron. The manufacture of the proposed mixture involves several operations: crushing of the metal components — silicobar, silicocalcium, and ferrosilicon. sifting out fractions of 0.2–3.2 mm, silicon carbide is taken as finished grade 53C according to OGT 2MT 74-8-78 with a grain size of 80-H, graphitized returns are used as graphite, used by the electrode industry with fractions of 1-g2 mm. Mixing to qx is carried out in a drum n, in accordance with their share in the mixture.

The iron smelting was carried out in an electric furnace with treatment in the ladle with known and proposed mixtures.

The chemical composition of the original to the following, wt.%:

0

Carbon 3.38-3.42

2.44-2.52

Silicon

Manganese

0.70-0.72

0.062-0.065 Sulfur

five

Phosphorus 0.074-0.076

The compositions of the known and proposed mixtures used in the smelting, are given in table. one...

The test results on the living honor and chilling depth are given in c. 2..

The mechanical properties of cast iron are given in table. 3

Technical and economic efficiency. The use of the proposed blend compared to the base modifier FS75, used at the plant for the production of cast iron, is determined by the reduction in losses from the bleaching marriage. When testing the proposed mixture, the rejection of castings for bleaching is 0.75%, while when using FS it is 75-8%. Reducing the loss of marriage provides savings by increasing the yield of 14.2 rubles. on. a ton of castings.

By reducing the chill depth, an economy of tool consumption is 1.2 rubles per ton.

The total economic effect of 15.4 rubles / ton.

Table 1

7.5

8.0

8.0

32.0 35.0 38.0

30.0

46.5

5 7 9

Known

table 2

Table 3

Claims (1)

MIXTURE FOR MODIFICATION OF GRAY IRON, containing barium, silicocalcium, graphite and ferrosilicon, characterized in that, in order to increase the duration (survivability) of the mixture, prevent bleaching and reduce toxicity and fire and explosion hazard when used in castings of a complex configuration, it contains barium in the form of silicobarium and additional silicon carbide and ferrotitanium in the following ratio of components, wt.%: Graphite 32-38 Silicocalcium 5-9 Silicobarium 6-10 Silicon carbide 35-40 Ferrotitanium 0.1-1.0 Ferrosilicon Rest SU .. ,, 1079684