RU2041967C1 - Method for production of hypereutectic aluminum-silicon alloys - Google Patents

Abstract

FIELD: production of alloys based on aluminum and silicon. SUBSTANCE: introduction of liquid silicon by portions provides for reduction of content of oxide inclusions in alloy and higher degree of assimilation of low-melting metals. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to non-ferrous metallurgy, and in particular to a technology for the production of alloys based on aluminum and silicon containing refractory and low-melting metals.

A method of producing an aluminum-silicon alloys comprising chromium hypereutectic silikoalyuminiya smelting, alloying with aluminum and its introduction copper and / or nickel in hypereutectic silikoalyuminy at a temperature of 900-1400 ^C. in the form of an alloy with zinc (SU, N 1286638, cl. C 22 C 1/02, 1987).

 The disadvantage of this method is that for the preparation of copper and / or nickel-zinc alloys used to introduce them into silicoaluminum, significant additional costs are required. In addition, the use of this method is limited by the need for zinc in the resulting alloy.

The closest to the invention by the technical essence and attainable result is a method for producing an aluminum-silicon alloys, comprising aluminum melt, the introduction of silicon in molten form with a temperature of 1600-1800 ^{° C} while maintaining the melt temperature of not higher than 850 ^{° C,} and adjustment of melt casting into molds (ed. St. N 1203917, class C 22 C 1/02, 1984).

 The disadvantage of this method is that due to the increased temperature of the process, metal losses from melt oxidation are significant, and the quality of the alloy is low, since there is a large heterogeneity of the alloy in chemical composition and an increased content of oxide inclusions in the alloy. In addition, the method at elevated temperatures with the introduction of liquid silicon does not provide for the rational introduction of refractory and low-melting metals, the losses of which are significant according to the known method.

 The aim of the invention is to increase the degree of assimilation of fusible metals, reducing metal loss from oxidation of the melt and improving the quality of the alloy.

This is achieved by the fact that according to the method for producing hypereutectic aluminum-silicon alloys, which includes introducing liquid silicon into the melt, which is first introduced into the melt until a eutectic composition is obtained, moreover, together with a part of the refractory metals previously supplied to the liquid silicon in an amount equal to (0, 7-1,2) the ratio of silicon content in the final alloy eutectic and then the melt is cooled to 620-680 ^C and is doped with low-melting metals, after which the remaining portion of the liquid introduced into the silicon and refractory metal in.

The introduction of liquid silicon into the melt to obtain a eutectic composition, moreover, together with part of the refractory metals supplied previously to liquid silicon in an amount equal to (0.7-1.2) of the ratio of silicon contents in the eutectic and the final alloy, followed by cooling of the melt to 620-680 ^о С and alloying it with low-melting metals and further with the introduction of the remaining parts of liquid silicon and refractory metals, provides an increase in the degree of assimilation of low-melting metals, reduction of metal losses from oxidation of the melt and improving the quality of the alloy.

Introduction into the melt liquid silicon first part until the eutectic composition, followed by cooling to prevent overheating of the melt above 850 ^{° C,} which is inevitable when administered to the entire amount of the liquid silicon to obtain a final hypereutectic alloy and simultaneously provides favorable conditions for the introduction of low-melting metals such as magnesium, zinc at a temperature of 620-680 ° ^C.

 This results in a corresponding reduction of metal losses from oxidation of the melt and an increase in the degree of assimilation of fusible metals. The introduction of molten silicon together with refractory metals into the melt is due to the variable silicon content in the final alloy (depending on the grade of the alloy), which results in uniform introduction of refractory metals into the melt throughout the entire melting process, which favorably affects the alloy's uniformity in chemical composition. A decrease in the oxidation of the melt due to a decrease in the temperature of the melting process contributes to a decrease in the content of oxide inclusions in the alloy, which, like an increase in uniformity in chemical composition, has a positive effect on the quality of the alloy.

 The introduction of the remaining parts of liquid silicon with refractory metals makes it possible to increase the temperature of the melt with overheating over the liquidus necessary for casting an alloy of various compositions into silicon.

 The selected conditions are limited by the following factors.

Cooling the melt eutectic composition to a temperature above 680 ^{° C} does not provide the increase of the degree of assimilation of fusible metal and reducing metal losses due to oxidation of the melt and before temperatures below 620 ^{° C} is impractical due to reduced degree of assimilation of refractory metals have been reduced to overheat the melt above the liquidus at the introduction of the remaining parts of silicon and refractory metals.

 An increase in the number of refractory metals preliminarily fed into liquid silicon to obtain a eutectic composition, more than 1.2 ratios of silicon contents in the eutectic and final alloy, leads to an increase in the loss of refractory metals from oxidation of the melt, and less than 0.7 to a decrease in the uniformity of the alloy in chemical composition .

The implementation of the method is carried out in the preparation of aluminum-silicon alloy grade AK-21, containing refractory and low-melting components. For liquid silicon alloy is used at release it from the furnace rudovosstanovitelnoy RKO-type silicon 25KrI after melting (at a temperature of 1600-1800 ° ^C). As alloying refractory metals, manganese is used in the form of pieces with sizes of 30-40 mm in diameter, copper in the form of sheet cathodes, nickel in the form of plates and granules, and magnesium in pigs as low-melting metals.

EXAMPLE EXAMPLE 1 The ladle with molten and heated to 750 ^{° C} the aluminum (in an amount of 3765 kg of convenience) is introduced through a chute liquid silicon at a temperature ^of 1700 C together with refractory metals: manganese, copper and nickel, respectively, 15, 34 and 32 kg or 0.7 ratios of silicon contents in the eutectic (Si 12.5%) and final (Si 21%) alloy. In total, liquid silicon is introduced in an amount of 553 kg until a melt of eutectic composition is obtained. Then, the melt eutectic composition is cooled to 620 ^{° C} and is doped with magnesium in an amount of 28 kg, and then introduced into the remaining portion of the liquid silicon (552 kg) and refractory metals (Mn 21, Cu 47 Ni and 44 kg). Get 5000 kg of alloy AK-21 with the actual content of the components, wt. silicon 21; manganese 0.7; copper 1.6; nickel 1.5 and magnesium 0.5. Before casting, samples of the alloy are taken to determine its uniformity in chemical composition. The quality of the metal is also evaluated by the presence of stroke defects (macro analysis of milled templates from deformed samples).

 In examples 2 and 3, this alloy is obtained analogously to example 1 with the following parameters.

PRI me R 2. The temperature of the melt of the eutectic composition after cooling 650 ^about C.

 The amount of refractory metals introduced into the eutectic composition melt, kg: Mn 21; Cu 48; Ni 45 or 1.0 of the ratio of the silicon content in the eutectic and final alloy (12.5: 21.0).

PRI me R 3. The temperature of the melt of the eutectic composition after cooling 680 ^about C.

 The amount of refractory metals introduced into the eutectic composition melt, kg: Mn 26; Cu 58; Ni 54 or 1.2 from the ratio of silicon contents in the eutectic and final alloy (12.5: 21.0).

 In examples 4 and 5, the alloy is obtained analogously to examples 1-3 outside the declared intervals.

 Get a similar alloy by a known method.

 The test results are shown in the table.

 The table shows that the use of the proposed method for the production of hypereutectic aluminum-silicon alloys containing refractory and low-melting metals, provides an increase in the degree of assimilation of low-melting metals by 8.3 abs. and reduction of metal losses from melt oxidation by 20%, including aluminum by 15%. The quality of the alloy improves both by increasing its uniformity in chemical composition and by reducing oxide inclusions in the alloy (the defectiveness coefficient characterizing the purity of the metal decreases by 1 , 7 times).

Claims (1)

METHOD FOR PRODUCING ZAEUTEKTIC ALUMINUM-SILICON ALLOYS containing refractory and low-melting metals, including melting aluminum, introducing silicon into the melt, characterized in that silicon is introduced in liquid form in parts, initially in an amount sufficient to obtain a eutectic composition, together with metals, together with metals the amount of refractory metals is determined as 0.7 1.2 the ratio of the silicon content in the eutectic and final alloy, then the melt is cooled to 620 - 680 ^o C and alloyed with low-melting metals and then the remainder of the liquid silicon and refractory metals is introduced.

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