Aluminum casting alloys are regulated by GOST 1583-93, which applies to alloys in ingots used as metal charge, and alloys in finished castings (39 grades in total). In accordance with GOST 1583-93, when marking an alloy, a combined (double) designation is used: first, the alloy grade in ingots is indicated, then in brackets - the alloy grade for finished shaped castings, for example: AK12 (AL2), AK13 (AL13), AK5M (AL5) .

Alloys in ingots are marked as follows. The letter “A” is indicated first, which indicates that the alloy is aluminum. Then the letters indicate the name of the main or alloying elements, followed by a number indicating the average percentage content of these components. The following designation for the components included in aluminum cast alloys is accepted: K - silicon; Su - antimony; Mts - manganese; M - copper; Mg - magnesium; N - nickel; C - zinc. For example: AK12 is an aluminum alloy with an average Si content = 12%; AK10Su- contains 10% silicon and has antimony as an alloying element, the rest is A1; AMg4K1, 5M - an alloy containing magnesium - 40%, silicon - 1.5, copper about 1.0%, the rest - A1.

The alloy grade in castings is designated in two ways:

The first is in the letters AL (A - aluminum, L - casting), followed by numbers indicating the alloy number. These numbers are conditional and have no connection with the chemical composition or mechanical properties. Example of designation - AL2, AL4, AL19;

The second is similar to alloys in ingots.

In design documentation when marking shaped castings, the standard allows the alloy grade to be indicated without an additional brand designation in brackets, or only the grade indicated in brackets.

In the educational process, when the chemical composition of the metal of the finished casting is indicated, it is allowed to use the designation according to the first method (AL...); when it comes to the charge (ingots) used for melting, then the brand of ingots can be indicated according to the second method (AK..). .).

3.2.1. Classification and properties of aluminum alloys

According to their intended purpose, structural aluminum casting alloys can be divided into the following groups:

alloys characterized by high tightness: AK12 (AL2), AK9ch (AL4), AK7ch (AL9), AK8MZch (VAL8), AK7pch (AL9-1), AK8l (AL34), AK8M (AL32);

high-strength, heat-resistant alloys: AM5 (AL 19), AK5M (AL5), AK5Mch (AL5-1), AM4.5 Kd (VAL10);

corrosion-resistant alloys: AMch11 (AL22), ATs4Mg (AL24), AMg10 (AL27), AMg10ch (AL27-1).

The letters at the end of the stamp indicate: h - pure; pch - increased purity; och - special purity; l - casting alloys; c - selective.

Refined alloys in ingots are designated by the letter “p”, which is placed after the designation of the alloy grade. Alloys intended for the manufacture of food products are designated by the letter “P”, which is also placed after the alloy grade.

Aluminum foundry alloys in ingots (metal charge) and in castings are produced for the needs of the national economy and for export in accordance with GOST 1583-93.

The grades and chemical composition of aluminum casting alloys must correspond to those given in table. 3.14.

Silumins in pigs are produced with the following chemical composition:

AK12ch (SIL-1): silicon 10-13%, aluminum - base; impurities, %, no more than: iron 0.50, manganese 0.40, calcium 0.08, titanium 0.13, copper 0.02, zinc 0.06;

AK12pch (SIL-0): silicon 10-13%, aluminum - base; impurities, %, no more than: iron 0.35, manganese 0.08, calcium 0.08, titanium 0.08, copper 0.02, zinc 0.06;

AK12och (SIL-00): silicon 10-13%, aluminum - base; impurities, %, no more than: iron 0.20, manganese 0.03, calcium 0.04, titanium 0.03, copper 0.02, zinc 0.04;

AK12zh (SIL-2): silicon 10-13%, aluminum - base; impurities, %, no more than: iron 0.7, manganese 0.5, calcium 0.2, titanium 0.2, copper 0.03, zinc 0.08.

By agreement between the manufacturer and the consumer, silumin of the AK12zh (SIL-2) brand is allowed to contain up to 0.9% iron, up to 0.8% manganese, and up to 0.25% titanium.

Alloys AK7, AK5M2, AK9, AK12 are used for the manufacture of food products. The use of other grades of alloys for the manufacture of products and equipment intended for contact with food products and environments must be permitted by health authorities in each individual case.

In aluminum alloys intended for the production of food products, the mass fraction of lead should be no more than 0.15%, arsenic no more than 0.015%, zinc no more than 0.3%, beryllium no more than 0.0005%.

In refined alloys, the hydrogen content should be no more than 0.25 cm 3 /100 g of metal for hypoeutectic silumins, 0.35 cm e /100 g for hypereutectic silumins, 0.5 cm 3 /100 g for aluminum-magnesium alloys; porosity should be no more than three points.

Depending on the chemical composition, aluminum alloys are divided into five groups (Table 3.14).

The first group is alloys based on A1-Si-Mg; To obtain a fine-grained structure, it is necessary to apply modification.

The second group is alloys based on the A1-Si-Cu system; good casting properties are explained by the optimal combination of silicon and copper content; This content of alloying elements allows the use of heat treatment to improve the mechanical properties of alloys.

The third group is alloys based on the A1-Cu system; They have the ability to undergo heat treatment, after which their mechanical properties improve; casting properties are worse than those of silumins.

The fourth group is alloys based on the A1-Mg system; have increased mechanical properties due to alloying with titanium, beryllium, zirconium; alloys of this group withstand high static and shock loads.

Fifth group - alloys based on the A1-other elements system (Ni-Ti, etc.); have heat-resistant properties, that is, they work well at elevated temperatures; the same can be said about pressures.

Analyzing GOST 1583-93, it is clear that some alloys of the same brand, used for metal charges and shaped castings, have differences in chemical composition: in alloys for castings, a slight decrease in the magnesium content and an increase in the content of harmful impurities is allowed.

* The amount of impurities taken into account depends on the type of casting.

Notes:

1. The designations of alloy grades according to GOST 1583-89, OST 48-178 and technical specifications are indicated in brackets.
2. The fractions in the numerator show data for ingots, and the denominator for castings.
3. It is allowed not to determine the mass fraction of impurities in alloys during the production of castings from a metal charge of a known chemical composition (with the exception of iron impurities).
4. When using alloys of grades AK12 (AL2) and AMg3Mts (AL28) for parts operating in sea water, the mass fraction of copper should not exceed: in alloy grade AK12 (AL2) - 0.30%, in alloy grade AMg5Mts (AL28) - 0 ,1%.
5. When using alloys for injection molding, the absence of magnesium in the AK7Ts9 (AL 11) alloy is allowed; in the AMg11 (AL22) alloy the content of magnesium is 8.0-13.0%, silicon 0.8-1.6%, manganese up to 0.5% and the absence of titanium.
6. Alloys of the AK5M7 (A5M7), AMg5K (AL13), AMg10ch (AL27), AMg10ch (AL27-1) grades are not recommended for use in new designs.
7. The absence of boron in the AK8M3ch (VAL8) alloy is allowed, provided that the level of mechanical characteristics provided for by this standard is ensured. When manufacturing parts from AK8M3ch (VAL8) alloy using liquid stamping, the mass fraction of iron should be no more than 0.4%.
8. When casting under pressure in the AK8 (AL34) alloy, it is allowed to reduce the limit of the mass fraction of beryllium to 0.06%, increase the permissible mass fraction of iron to 0.1% with a total mass fraction of impurities of no more than 1.2% and the absence of titanium.
9. To modify the structure of the alloys AK9ch (AL4), AK9pch (AL4-1), AK7pch (AL9), AK7pch (AL9-1), the introduction of strontium up to 0.08% is allowed.
10. Impurities indicated by a dash are taken into account in the total amount of impurities, while the content of each element does not exceed 0.020%.
11. By agreement with the consumer, it is allowed to produce pigs, the composition of which, in terms of mass fractions of individual elements (main components and impurities), differs from that indicated in the table. 3.14.
12. When using alloys for injection molding, the content of beryllium impurities up to 0.03% and silicon up to 1.5% in the AMg7 (AL29) alloy is allowed.
13. In the AMg11 (AL22) alloy, the absence of titanium is allowed.

Secondary pig casting alloys are obtained by processing shavings, waste, and imported metal scrap. The chemical composition of secondary aluminum casting alloys in ingots used as charge materials must comply with the requirements of GOST 1583-93.

The possibility of using a particular alloy is determined by its mechanical, physical and technological properties, as well as taking into account the economic characteristics of the alloy, which in many cases is decisive.

The mechanical properties of aluminum casting alloys according to GOST 153-93 must correspond to those given in table. 3.17.

Notes:

Symbols of casting methods: 3 - sand casting; B - lost wax casting; K - chill casting; D - injection molding; PD - casting with crystallization under pressure (liquid stamping); O - casting in shell mold; M - the alloy is subject to modification.

Symbols for types of heat treatment: T1 - artificial aging without pre-hardening; T2 - annealing; T4 - hardening; T5 - hardening and short-term (incomplete) aging; T6 - hardening and complete artificial aging; T7 - hardening and stabilizing tempering; T8 - hardening and softening tempering.

The mechanical properties of AK7Ts9 and AK9Ts6 alloys are determined after at least one day of natural aging.

The mechanical properties specified for casting method B also apply to shell casting.

Technological properties of aluminum alloys (Table 3.24) affect the quality of castings. These properties of alloys include: fluidity, shrinkage (volumetric and linear), tendency to form porosity and cavities, tendency to form casting stresses and cracks, gas absorption and formation of non-metallic inclusions, film formation and tendency to form a coarse-grained and columnar structure.

3.2.2. The influence of chemical elements on the properties of aluminum alloys

The influence of individual chemical elements on the properties of cast aluminum alloys is given in Table. 3.25.

3.2.3. Features of aluminum alloys and their areas of application

Cast aluminum alloys have a number of features: increased fluidity, which ensures the production of thin-walled and complex configuration castings; relatively low linear shrinkage; reduced tendency to form hot cracks. In addition, aluminum alloys have a high tendency to oxidation and saturation with hydrogen, which leads to such types of casting defects as gas porosity, slag inclusions and oxide inclusions. Therefore, when developing melting technology and manufacturing shaped castings using any of the casting methods, it is necessary to take into account the characteristics of individual groups of aluminum alloys.

The most widespread in industry are A1-Si-Mg alloys, which are distinguished by good technological properties, determined by the type of phase diagram. Their structure is an α-solid solution of silicon in aluminum and a eutectic, consisting of an α-solid solution and silicon grains. Casting properties are ensured by the presence in the alloys of a large amount of double eutectic α + Si (40-75%) of the frame-matrix type, the basis of which is an α-solid solution, which determines the high fluidity of the alloys, as well as low casting shrinkage and a reduced tendency to form hot cracks .

With an increase in the amount of eutectic in the alloys, the tendency to form shrinkage micro-looses decreases, which increases the tightness of the castings.

The crystallization process of these alloys occurs in a narrow temperature range and proceeds in a continuous front from the peripheral zone (mold walls) to the internal zones of the castings, which causes the formation of a continuous layer of fine-grained eutectic between the primary crystals. This prevents the formation of through shrinkage channels between the grains of the solid solution.

As the silicon content in alloys increases, the coefficient of thermal expansion decreases and a coarser structure is obtained, which leads to embrittlement of the alloy and deterioration in machinability. To grind silicon inclusions in the eutectic, modification of Na, Li, Ka, Sr is used, which increases plastic properties (δ = 5-8%).

To modify silumins, mixtures of sodium and potassium chloride and fluoride salts of various compositions are used, and about 0.01% Na is absorbed by the alloy. When modifying Na, the eutectic is overcooled by 15-30 °C, and the eutectic point shifts to 13-15% Si. The higher the silicon content in the alloy, the greater the modification effect, since the modifier affects only this phase. For silumins containing less than 5-7% Si, modification does not affect the mechanical properties.

Iron in A1-Si alloys forms the β(A1-Fe-Si) compound in the form of brittle plates, which sharply reduce ductility. The negative effect of iron is effectively reduced by the addition of 0.2-0.5% Mn, and a new phase a (A1-Fe-Si-Mn) is formed in the form of compact equiaxed polyhedra, which have a lesser effect on plasticity.

Alloy AL2 (eutectic) is the only double alloy of the first group, it belongs to simple silumins. The eutectic composition of the alloy (10-13% Si) ensures high fluidity and lack of tendency to porosity and crack formation. The alloy is used to produce dense, hermetic castings with a concentrated shrinkage cavity. The alloy is used in a modified state, mainly without heat treatment. Lightly loaded parts are manufactured using various casting methods. The lowest properties are obtained when casting in sand molds; when casting in a chill mold or under pressure, the strength and plastic properties increase noticeably.

Hypoeutectic special silumins (AL4, AL9, AL4-1, AL9-1) have higher mechanical properties, but are inferior in technological properties to the eutectic alloy AL2. Strengthening is achieved through the formation of the Mg 2 Si compound. The reduced silicon content allows the alloys to be used for injection molding and die casting without modification. When casting in sand molds and lost wax, it is recommended to modify the alloys.

Alloys AK7 and AK9 differ from alloys AL4 and AL9 in their increased content of impurities, but lower ductility.

The advantage of alloys based on the A1-Si-Mg system is their increased corrosion resistance in a humid and sea atmosphere - AK12 (AL2), AK9ch (AL4), AK7ch (AL9).

The disadvantages of these alloys are increased gas porosity and reduced heat resistance. The technology for casting these alloys is more complex and requires the use of modification and crystallization operations under pressure in autoclaves. This especially applies to the AK9ch (AL4) alloy.

Alloys based on the A1-Si-Cu system, which are characterized by high heat resistance (operating temperatures 250-270 ° C), but are inferior to A1-Si-Mg alloys in casting properties, corrosion resistance and tightness; do not require modification or crystallization under pressure.

The heat resistance of alloys is ensured by the content of stable refractory phases, which crystallize in a thin branched form and well block the grain boundaries of the solid solution, which inhibits the development of diffusion processes.

Alloys based on the A1-Cu system are characterized by high mechanical properties. Phase composition in the cast state: α-solid solution of copper in aluminum + CuA1 2. If the alloy contains impurities of silicon and iron, the phases A1 7 Cu 2 Fe, AlCuFeSi and the ternary eutectic α + Si + AlCu 2 with a melting point of 525 ° C can be formed. Increasing the silicon content in alloys to 3% leads to an increase in the amount of eutectic and improved casting properties, but to a significant decrease in strength. The presence of 0.05% Mg greatly reduces the weldability of alloys and their ductility.

The strength of alloys based on the A1-Mg system increases with an increase in magnesium concentration to 13%, but ductility begins to decrease at a content of more than 11% Mg; the main strengthening phase is the chemical compound β (A1 3 Mg 2).

For casting alloys, alloys containing Mg are used, % (wt. fraction):

4.5-7 - medium strength alloys used without heat treatment AKMg5K (AL13), AMg6l (AL23);

9.5-13 - high-strength alloys used in the hardened state AMg10 (AL27), AMg11 (AL22).

To improve technological properties, up to 0.15-0.2% titanium and zirconium are added to most alloys. The TiA1 3 and ZrA1 3 intermetallic compounds formed on their basis are more refractory than the alloy base and are modifiers of the first kind. Mechanical properties increase by 20-30%.

Alloys based on the Al-Mg system have an increased tendency to form gas and gas-shrinkage porosity, and when interacting with nitrogen and water vapor, non-metallic inclusions and oxide films are formed. Melting of alloys should be carried out under a layer of flux, and if they contain Be, without flux.

Alloys based on the A1 system and other components (complex alloys) include the following alloys: heat-resistant multicomponent and self-hardening corrosion-resistant AC4Mg (AL24), piston alloys AK12M2MgN (AL25), as well as zinc silumin AK7Ts9 (AL11).

Alloy ATs4Mg (AL24) belongs to the Al-Zn-Mg system, the main strengthening phase is T(A1 2 Mg 3 Zn 3). The high stability of solid solutions of zinc and magnesium in aluminum ensures “self-hardening” of the alloy during the cooling of the casting. The alloy can be used without special hardening, in a cast and naturally or artificially aged state. The alloy has satisfactory properties, which are improved by the addition of titanium (0.1-0.2%). It is recommended for sand casting, investment shell molds, welded parts, as well as parts with increased dimensional stability and corrosion resistance.

Eutectic special silumins AK12M2MgN (AL25), having good casting properties, are characterized by higher heat resistance, since they contain 0.8-1.3% Ni, which forms complex phases in the form of a rigid frame; titanium additive improves technological properties. The alloys have a low tendency to volumetric changes during operation at elevated temperatures; used for the manufacture of pistons; in this case, the castings are used without hardening. To relieve internal stresses, the pistons are thermally treated according to the T1 mode.

Zinc silumin AK7Ts9 (AL11), containing 7-12% Zn, which is highly soluble in solid aluminum, creates solution strengthening, which allows the alloy to be used in a cast state (without heat treatment). It has good technological properties, the ability to maintain strength, hardness and resistance to alternating loads after short-term and long-term heating to temperatures of 300-500 °C. The alloy is used for cast parts in engine building and other industries, used for casting in sand-clay molds, chill molds and under pressure. It has reduced corrosion resistance and relatively high density.

One of the main categories of light metals that are widely used in various industries are aluminum-based alloys. The most common of them is the AK12 casting alloy. For successful practical use of metal, specialists need to be able to correctly manage information about its purpose, composition and properties.

Alloy characteristics

In various fields of industry, along with high-strength alloys based on ferrous metals (steel, cast iron), lightweight compounds based on aluminum and silicon - silumins - are widely used. They are distinguished by greater strength and wear resistance in comparison with pure aluminum, but are somewhat inferior to aluminum-copper compounds.

One of the most common aluminum-silicon alloys is AK12. It belongs to the foundry category.

According to the outdated classification, it was marked with the letters AL - cast aluminum.

AK12 can be divided into three groups according to its properties:

Physical

• specific heat capacity - 838 J/(kg*deg);
• elastic modulus - 0.7 MPa;
• density - 2650 kg/m3;
• coefficient of thermal expansion - 21.1 1/degree;
• specific electrical resistance - 54.8 Ohm*m.

Mechanical

• Brinell hardness - HB 10-1=50 MPa;
• temporary tensile strength when casting in a chill mold or under pressure - 147-157 MPa;
• relative elongation when casting in a chill mold - 2-3%;
• relative elongation during injection molding is 1-2%.

Foundry-technological

• linear shrinkage coefficient - 0.8%.

Silumin is hermetically sealed and very resistant to corrosion. For the AK12 alloy used in sea water, the proportion of copper in accordance with the requirements of the standard should not exceed 0.3%. The alloy also exhibits excellent anti-corrosion properties in other environments:

• slightly acidic;
• alkaline;
• in high humidity conditions.

The negative properties of the AK12 alloy include the following: - brittleness during machining.

• high porosity;
• coarse-grained eutectic structure of castings;
• low threshold for physical activity.

It is impossible to achieve an increase in strength by heat treatment (hardening) of alloy castings.

Chemical composition

According to GOST 1583-93 “Aluminum casting alloys” AK12 has the following chemical composition:

1. Base metals

• aluminum - 84.3-90%.
• silicon - 10-13%.

2. Impurities

• iron - up to 1.5%
• copper - up to 0.6%
• manganese - up to 0.5%
• zinc - up to 0.3%
• magnesium and titanium - up to 0.1%

The alloy achieved high mechanical properties after modification with chemical additives:

• sodium;
• potassium;
• lithium

In some cases, salts of the above chemical elements can also be used. The proportion of modifiers in the alloy composition does not exceed 0.01%. Their purpose is to increase the ductility index during casting by bonding silicon atoms.

In addition to traditional modifiers, recently the technology of adding compounds based on strontium, which is resistant to waste, has become widely used. Also, its addition does not lead to an increase in gas shrinkage and porosity of the casting. AK12 with the addition of strontium retains its physical and chemical structure after repeated remelting.

Practical application of AK12 alloy

Due to its high fluidity index, the alloy is widely used in the production of parts operating in environments with temperatures up to 200ºC. Silumin castings are made in three ways:

• under pressure.
• using a metal casting mold (chill).
• using a sand casting mold.

The most popular form of finished castings from AK12 on the market is pigs weighing up to 15 kg.

In accordance with the requirements of the casting standard, the following information is applied by imprint:

• alloy name;
• heat number;
• weight.

The packaging must be accompanied by a certificate indicating the exact chemical composition of the alloy.

The areas of application and range of products made from AK12 are unusually wide:

• automotive industry, aircraft industry - cylinder blocks, pistons and crankcases.
• housing and communal services - shut-off valves for plumbing work, heat exchangers for heating devices.
• Some types of kitchen appliances are made from silumin.

Melting aluminum alloys presents a number of difficulties. The low density of aluminum alloys promotes the formation of gas pockets and porosity, since gases easily penetrate the metallic environment and saturate it. Aluminum oxidizes easily. It is difficult to clean the melt from slag and oxides. Slag and oxides remain in the melt in a finely divided form in a suspended state, which significantly affects the quality of the alloy.

The use of fluxes (zinc chloride, cryolite) or modifiers also does not allow the melt to be completely cleaned, since it is difficult to separate them from the melt.

When preparing aluminum alloys, the purity of the starting materials and the accuracy of the charge composition are especially important. Often, insignificant amounts of harmful impurities significantly worsen the mechanical properties of alloys. All this necessitates particularly careful waste sorting. Without remelting, they can be used only if their chemical composition is known. Scrap of unknown origin or poorly sorted and remelted (secondary alloys) containing many oxides and harmful impurities should be melted into pigs. During remelting, the melt is cleaned of impurities and a chemical analysis is performed.

Melting and pouring of aluminum is carried out under strict adherence to the temperature regime and constant and precise control of the heating of the alloy. Even slight overheating and excessive holding of the alloy at high temperatures lead to its excessive saturation with gases and oxides and the appearance of shrinkage cavities.

To remove oxides and slags, it is necessary to use fluxes that act both chemically and mechanically. After cleaning the melt from oxides, it should not be stirred.

Pouring must be done carefully, using a short stream.

When preparing aluminum alloys, the following order should be followed:

melting about 2/3 of pig aluminum;

additive and melting of alloy;

additive of the remaining pig aluminum;

additive of waste and gates;

cleaning the melt from oxides after it has melted by adding cleaning fluxes and good mixing;

removing the crucible and removing slag and oxides (slag should not be removed during melting, since the surface film of oxides protects the melt from further oxidation);

holding the melt to the required temperature before pouring.

An example of melting aluminum alloy AK12 (AL2).

Alloy AK12 (AL2) can be made from pig silumins. In the absence of silumins, pig aluminum and silicon can be used as charge materials.

The alloy is prepared as follows: pig aluminum is melted and heated to a temperature of 850 ° C. Silicon is added in small portions to the heated aluminum, which is wrapped in aluminum foil before being introduced into the aluminum so that it is not covered with aluminum oxide, which makes it difficult to dissolve silicon. After complete dissolution of all silicon, the alloy is refined and modified.

Aluminum alloys are melted in crucible and flame stationary, rotary and tilting furnaces, electric resistance furnaces and induction furnaces. Melting of aluminum alloys in electric resistance furnaces is as follows.

Charge materials, which are heated pigs of primary and secondary alloy, waste from in-house production and corresponding alloys, are loaded into chambers lined with fireclay bricks. In the chambers in the shaped refractory there are electric spirals through which an electric current passes, heating them.

The melt from the chambers flows into the collection tank. In the collection, the melt is refined with zinc chloride, thoroughly mixed, pitch and slag are removed from the surface, and then additives are added. Before pouring into ladles, the melt is mixed again, slag is removed from the melt surface, the temperature is measured with an immersion thermocouple, and samples are poured to control chemical analysis and mechanical properties.

Before being released into the ladle, silumin alloys are modified with sodium metal salts to obtain a fine-grained structure. In some cases, alloys are purged with chlorine at a temperature of 680-720° for degassing. When the furnace is tilted using a turning mechanism and rollers, the melt is poured through a chute into the pouring ladles. The capacity of resistance furnaces is 0.3-3.0 tons, the number of heats per day is 4-5.

Charge materials

To produce aluminum alloys, pig aluminum, machine scrap, foundry waste and various alloys are used (for example, 90% Al and 10% Mn, melting point 770 - 830°).

The composition of the metal charge includes 40 - 60% of circulating metals (scrap, rejects, sprues, blowouts, profits, etc.) and 60 - 40% of pure metals. To protect the metal from oxidation, fluxes of various compositions are used, for example 50% NaCl + 50% CaCl2; or 50% NaCl + 35% KCl + 15% Na3AlF6.

All these fluxes are low-melting (melting point in the range of 500 - 600º). To obtain a dense metal with a finer structure, modifiers are added to it. For aluminum alloys, pure sodium and its salts are used as a modifier: 67% NaF + 33% NaCl, or 25% NaF + 62.5% NaCl + 12.5% ​​KCl. Al2, Al4, etc. alloys are subject to modification.

Furnaces for melting aluminum alloys. Aluminum alloys are melted in the following furnaces: rotary crucible furnaces with a metal crucible (Fig. 83, a); in electric crucible resistance furnaces, stationary and rotary (for preparing up to 0.25 tons of alloy); stationary and rotary resistance chamber furnaces (Fig. 83, b) with a capacity of up to 1.5 tons; induction two-channel furnaces with a metal core.

Rice. 83. Melting furnaces for melting aluminum alloys: a - crucible forge; b - resistance electric furnace: 1 - loading window; 2 - bath for melting metal; 3 - resistance

The process of melting aluminum alloys presents a number of difficulties due to their strong oxidation and saturation with gases when heated above 800°. There are several melting methods that ensure the production of high-quality castings; submerged smelting, gas refining, salt refining, freezing and modification.

Melting of aluminum alloys under a layer of fluxes takes place in the following sequence; the charge materials are tightly placed in a crucible or furnace and covered with fluxes on top; the metal is loaded and melted in parts: first, about a third of the charge is melted, then the remainder of the charge material is heated to 100 - 120 ° to remove moisture from the surface and immersed in the molten metal under a layer of fluxes.

During gas refining, smelting is carried out in the following sequence: a third of the charge is loaded and melted, alloys (Al + Cu, Al + Si, etc.) and the remainder of the charge are added. After melting, the alloy is stirred, heated to 660 - 680° and refined with chlorine. Refining is carried out by blowing chlorine through the alloy for 5 - 15 minutes. In this case, chlorine enters into a chemical interaction with aluminum and other elements.

The resulting gaseous products AlCl3, HCl and part of Cl2 are removed from the metal, adding Al2O3, SiO2 and gases. After gas refining, the metal acquires high mechanical properties. Nitrogen can be used for gas refining.

Request a price

Ask a Question

The list of products offered by Orion-Spetssplav-Gatchina LLC includes aluminum casting alloys AK12, AK12Ch, AK12PCh, AK12och. The company sells metal of its own production and guarantees consistently high quality through careful control of characteristics. Orion-Spetssplav-Gatchina LLC is a regular supplier to large Russian and foreign enterprises.

Description, features and application of alloys AK12, AK12ch, AK12pch, AK12och

The alloys are aluminum with the addition of 10-13% silicon, which performs alloying functions. Depending on the brand, these alloys have clear restrictions on the content of iron, manganese, calcium, titanium, copper, and zinc.

Lower casting temperatures help reduce production costs when producing parts. Due to the content of silicon additives in the composition, alloys of the AK12 series have low density, increased fluidity, and minimal linear shrinkage. The alloys are not prone to cracking during casting and lend themselves well to welding

Silumins AK12, AK12Ch, AK12PCh, AK12och are widely in demand in mechanical engineering (heat exchangers, pumping equipment, adapters, elements of pipeline fittings),

in the manufacture of hermetic castings of complex shapes, in the manufacture of products for the food industry and other purposes.

Brand	Form	Compound	Marking	Standard	Price, dollars/ton, excluding VAT
AK12	Wafer ingot Size 400*200*40 mm Weight 5-7 kg	Al-84.3-90% Si 10-13%	White stripe, Green stripe Green stripe	GOST 1583-93 Customer's specifications G-AlSi12	on request
AK12h	Wafer ingot Size 400*200*40 mm Weight 5-7 kg	Al-85.8-90% Si-10-13%		GOST 1583-93 Customer's specifications	on request
AK12pch	Wafer ingot Size 400*200*40 mm Weight 5-7 kg	Al-86.3-90%, Si 10-13%		GOST 1583-93 Customer's specifications	on request
AK12och	Wafer ingot Size 400*200*40 mm Weight 5-7 kg	Al-86.6-90%, Si 10-13%		GOST 1583-93 Customer's specifications	on request

Aluminum alloy AK12 belongs to the silumin category. It contains 10-13% silicon and a small amount of other impurities. The alloy is characterized by low casting shrinkage, good tightness and hardness compared to other aluminum alloys, and good corrosion resistance. During casting, the alloy does not crack, but due to its relatively low short-term yield strength, it is used for the manufacture of parts operating under low loads.

The production of blanks and parts is carried out using casting (in the ground, chill mold, under pressure, shell molds). The alloy is used to make various parts of engines, household appliances, pump housings, and elements of firearms. It is allowed to manufacture food products from an alloy of a high degree of purity (subject to the appropriate permit).

• Release form: pigs 8-14 kg.
• Packaging: pack weighing 300-1000 kg
• Standard: GOST 1583-93
• Marking: on each pig there is an indelible imprint of the heat number, on the pigs of the top row of the pack the following information is painted: alloy grade, heat number, number of pigs and net weight of the package, excluding package weight.
• Documents: Upon shipment, a manufacturer's certificate of a unified form is issued indicating the Supplier, the Recipient of the goods, the chemical composition of the products for each package, net weight, gross weight, as well as a consignment note in the T-1 form. At the Buyer's request, the possibility of issuing additional necessary documents is also stipulated.
• Price on request

Chemical composition of AK12 alloy according to GOST 1583-93

Al	Si	Mn	Ti	Fe	Cu	Zr	Mg	Zn	Impurities
basic	10 - 13	up to 0.5	up to 0.1	0.7	up to 0.6	up to 0.1	up to 0.1	up to 0.3

Terms of sale and delivery of aluminum alloy AK12

You can buy aluminum ingots made from AK12 alloy from the capital company Pereplav. We specialize in the production of aluminum alloys and the sale of non-ferrous metals, offering customers reasonable prices and high quality products. The latter always meets the requirements of current standards, as confirmed by the relevant certificates.