SU1211299A1 - Method of producing aluminium cast iron with compact graphite - Google Patents

Description

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The invention relates to foundry, in particular, to methods for producing aluminum cast iron with compact (spherical and vermicular) graphite.

The aim of the invention is to increase the absorption of aluminum, improve the fluidity of cast iron and reduce the consumption of modifier.

According to the proposed method, the treatment of liquid iron is carried out in a reaction chamber located inside the mold, with a mixture of aluminum in the form of magnesium granules containing modifier and cryolite, and | the weight ratio of aluminum and cryolite in the mixture is 10: (0.5-2.5).

The use of aluminum in the form of pellets produced by industry for steel deoxidation (GOST 295-79) allows pouring the melt into the mold at the optimum speed, ensuring uniform heating and melting of both the aluminum itself and the magnesium-containing modifier, moreover, granular aluminum is more technologically logical and much cheaper than crushed by mechanical means.

The presence of powdered cryolite in the composition of the mixture reduces the oxidation of aluminum when it is introduced into the molten iron, thereby improving the fluidity of the latter and increasing the absorption of aluminum in the iron.

The positive role of cryolite as a flux in the composition of the doping-modifying mixture is due to its greater chemical affinity for oxygen, compared with aluminum.

The weight ratio of powdered cryolite and granulated aluminum (0.5-2.5): 10 was determined experimentally, based on the condition of the most efficient absorption of aluminum and magnesium in the iron, which is part of the modifier. With a smaller weight ratio of the amount of cryolite to aluminum, i.e. x: 0.5: 10, does not melt the mixture in the reaction chamber, but sintering and slagging from the surface. At the same time, the cast iron does not provide a specified form of graphite (spherical or vermicular). A higher content of cryolite in relation to aluminum, i.e. .2,5: 10, is redundant and leads to additional material

112992

 costs. The required amount of the magnesium-containing modifier is based on obtaining the desired form of graphite in the iron.

J Example The smelting of cast iron is carried out in a high-frequency induction furnace with the main lining, using as charge materials

Q Conversion iron

PL2% 85-80

Waste carbon steel ST.Z,% 15-20 Ferrosilicon

, 5 FS75,% Over 100

Pig iron and steel waste are loaded into the furnace crucible (to reduce the carbon content), after melting, ferrosilicon is introduced.

2Q Melt the cast iron of the composition (C 3.5%, Si 1.1%, Mn 0.5%, P 0.05%, S 0.03%) overheat, to 1480 ° C, spheroidizing modification and doping are carried out 25 MU method is known, according to the proposed method, in the reaction chamber located inside the mold. AB97 grade granulated aluminum (GOST 295-79) is used for alloying cast iron.

... As a modifier, an LCG-6 ligature is used (Si 51.0%, Mg 8.5%, Ca 5.0%, REM 1.1%, Fe balance).

Comparative data on the effectiveness of the proposed and known methods for producing pig iron in terms of digestion of aln-mini in it, on the fluidity of the melt after alloying-modifying treatment on the consumption of modifier and on the influence of the method of processing on the shape of graphite in cast iron

 are shown in the table.

According to a known method, aluminum and LCKK-6 ligature without cryolite are placed in a reaction chamber located inside the mold, and molten iron from induction jie4H is poured into the mold (see table, example 1 and 2) during the process of filling the mold, a significant pyro effect is observed.

50 According to the proposed method, the aluminum is mixed with powdered cryolite and LCG-6 ligature, the resulting mixture is placed into the reaction chamber and the melt is poured

55 cast iron in the mold at 1370-1420 s. At the same time, depending on the example (see the table, examples 3 and 9), they take a different:

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aluminum and cryolite, the content of magnesium-containing LCKK-6 ligature in the mixture also varies, and in examples 8 and 9 the ratio of aluminum to cryolite 10: (0.5-2.5) is taken. With a smaller ratio of the number of cryolite to granular aluminum (example 8), i.e. 0.5: 10, there is no melting of the mixture inside the reaction chamber, but its sintering and slagging from the surface. At the same time graphite in the cast iron has a plate shape. With more cryolite in relation to granular aluminum (example 9), i.e. 2.5: 10, there is no improvement in the properties, and therefore an increase in the amount of cryolite leads only to unnecessary additional costs.

The proposed method for producing compact graphite aluminum cast iron allows the stable assimilation of aluminum in cast iron, while also high melt flowability, which is very high.

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0.5 2.0

0.50.5: 10

0.52.5: 10

1,0t, 5: 10

2.02.0: 10

2.50.5: 10

1,00,3: 10

1,03,0: 10

Compiled by K. Sorokin Editor N. Gorvat Tehred Z. Kastelevich. Proofreader S. Shekmar

Order 611/31

Circulation 552

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch ShSh Patent, Uzhgorod, st. Project, 4

It is important for cast iron, which has in its composition easily acidic elements. If the proposed weight ratio of aluminum and powdered cryolite is observed, the mixture is uniformly and completely melted, thereby increasing the efficiency of magnesium absorption from the modifier, and this in turn reduces the consumption of expensive magnesium-containing master alloys by an average of 40%. When using the proposed method, the temperature of the melt in the alloying-modifying treatment

maintained within 1370-1420 0, while by a known method it should not be below 1420 C.

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The economic effect of the use of the invention is achieved by reducing the amount of aluminum that is introduced into the molten iron due to an increase in its absorption coefficient; a decrease by an average of 40% in consumption of 25 modifiers such as LCMK.

0,55 .52 Spherical capravicular fork

0.5 Ai Vermicular

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Claims (1)

METHOD FOR PRODUCING ALUMINUM CAST IRON WITH COMPACT GRAPHITE, comprising processing cast iron melt with aluminum and a magnesium-containing modifier, characterized in that, in order to increase the absorption of aluminum, improve the fluidity of cast iron and reduce the flow rate of the modifier, the cast iron melt is treated with a cryolite-magnesium mixture, and aluminum in a mixture (0.5-2.5): 10.