RU2623966C2 - Modification method of aluminium-silicon alloys - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method comprises adding flux containing a carbonaceous material, a titanium-containing material and barium carbonatein to the melt. The flux contains a titanium-containing material in the form of a potassium fluorotitanate salt. On the surface of an aluminium-silicon melt at a temperature of 760-770°C an amount of 2-3% of the melting weight, a flux is poured in a uniform layer, held for 2-3 minutes, and then kneaded into the melt to a depth of 10-20 centimeters with the formation of friable slag on the surface.

EFFECT: increasing the mechanical properties of aluminium-silicon alloys by simultaneous grinding of grains αof solid solution and eutectic during crystallization of the alloy and preserves the duration of the modifying effect.

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Description

The invention relates to foundry, namely, to the modification of aluminum-silicon alloys of pre-eutectic and eutectic compositions and can be used in the technology of preparation of aluminum-silicon alloys to obtain shaped castings.

The closest chemical composition (technical essence) is the composition for modifying and refining iron-carbon and non-ferrous alloys, which includes a material containing calcium, barium and strontium carbonates, while it contains components in the following ratio, mass. %: CaO - 16.0-40.0, BaO - 10.0-24.0, SrO - 2.5-11.5, CO ₂ - 18.0-30.0, SiO ₂ -2.0- 15.0. Additionally, a carbon-containing material or metallic aluminum in an amount of 2-35 wt. %, or titanium-containing material in an amount of 0.01-35 wt. %, or rare earth metals in an amount of 2-49.5 wt. % (see, for example, RF Patent No. 2502808, IPC С22С 1/06, С21С 7/00, С21С 1/00, published on December 27, 2013).

Since this composition is designed for processing iron-carbon alloys, its main drawback in the processing of aluminum-silicon alloys is its low modifying and refining ability. It has a low modifying effect on grains of α-solid solution. Therefore, aluminum-silicon alloys treated with this composition have low mechanical properties, especially ductility.

The basis of the invention is the task of developing a flux for the modification of aluminum-silicon alloys, in order to increase the mechanical properties of aluminum-silicon alloys by simultaneously grinding the grains of the α-solid solution and eutectic during the crystallization of the alloy and maintaining the duration of the modifying effect.

The problem is solved in that in the flux for the modification of aluminum-silicon alloys containing carbon-containing material, titanium-containing material and barium carbonate, the flux contains titanium-containing material in the form of a salt of potassium fluorotitanate and barium carbonate in the following masses. % component ratios:

50-57% K ₂ TiF ₆ ;

27-35% BaCO ₃ .

Since the flux contains a titanium-containing material in the form of a salt of potassium fluorotitanate and barium carbonate in the following masses. % component ratios:

50-57% K ₂ TiF ₆ ;

27-35% BaCO ₃ ,

the mechanical properties of aluminum-silicon alloys are enhanced by simultaneously grinding the grains of the α-solid solution and eutectic during the crystallization of the alloy and preserving the duration of the modifying effect.

The flux for the modification of aluminum-silicon alloys is obtained as follows.

In a SNOL brand muffle furnace in a chamotte-graphite crucible, AK12 aluminum-silicon alloy was prepared according to standard technology (in accordance with GOST 1583-93, the alloy contains 11.3% Si; 0.3% Fe; Al - the rest; the mechanical properties of AK12 alloy should be equal, not less than: temporary tensile strength, σв - 147 MPa, elongation, δ - 4%). At a temperature of 760-770 ° C, flux is introduced into the melt in an amount of 2-3% of the weight of the heat. The flux is poured evenly on the surface of the melt. It is aged for 2-3 minutes and then kneaded into the melt to a depth of 10-20 cm for 4-5 minutes until friable slag forms on the surface of the melt. After this, the resulting slag is removed from the surface of the melt. The alloy is aged for another 8-10 minutes, while its temperature is brought to a pouring temperature equal to 710-730 ° C. The formed slag is removed from the surface of the melt and standard samples are cast for mechanical tests by casting into the ground.

In tables 1 and 2 shows the comparative characteristics of the flux known from the prototype and the proposed flux.

A universal, environmentally friendly complex flux has been developed that allows for a long time to maintain modifying activity in liquid aluminum alloys. As a result of complex melt processing, the mechanical properties of aluminum alloys and the quality of castings are improved.

The use of complex flux in the processing of silumins during the smelting process compared to the standard flux for silumins allows you to:

1) to increase the mechanical properties of silumins (ductility - 90-100%, strength - 10-15%);

2) increase the duration of the effect of alloy modification during casting without additional melt processing from 30-40 minutes to 5 hours;

3) reduce the amount of harmful emissions into the atmosphere.

When using a standard flux containing alkali metal chloride salts, they actively evaporate into the atmosphere at smelting temperatures. The proposed flux does not contain chloride salts, which dramatically reduces the amount of harmful emissions into the atmosphere and increases the environmental friendliness of the process for modifying silumins.

The mechanism of a complex effect on the alloy structure is based on simultaneously occurring decomposition reactions of salts that are part of the flux and the interaction of decomposition products with carbide-forming substances.

A distinctive feature of the created product is its versatility, environmental friendliness, an increased level of properties of aluminum-silicon alloys, an increased duration of the effect of the modification in comparison with the existing standard fluxes currently used in foundry production.

Claims (1)

A method for modifying aluminum-silicon alloys, including introducing a flux containing carbon-containing material, titanium-containing material and barium carbonate into the melt, characterized in that a titanium-containing material is used in the form of potassium fluorotitanate salt, while on the surface of the aluminum-silicon melt at a temperature of 760-770 ° C in an amount of 2-3% of the weight of the melt, a flux is poured with a uniform layer, kept for 2-3 minutes, and then kneaded into the melt to a depth of 10-20 cm with the formation of friable slag on the surface.