Today, aluminum is used in almost all industries, from the production of food utensils to the creation of spacecraft fuselages. For certain production processes, only certain types of aluminum are suitable that have certain physicochemical properties.
The main properties of the metal are high thermal conductivity, ductility and ductility, corrosion resistance, light weight and low ohmic resistance. They are directly dependent on the percentage of impurities that make up its composition, as well as on the technology of production or enrichment. In accordance with this, the main brands of aluminum are distinguished.
Types of aluminum
All metal grades are described and included in a single system of recognized national and international standards: European EN, American ASTM and international ISO. In our country, aluminum grades are defined by GOST 11069 and 4784. In all documents, aluminum and its alloys are considered separately. Moreover, the metal itself is subdivided precisely into grades, and alloys do not have specific signs.
In accordance with national and international standards, two types of microstructure of unalloyed aluminum should be distinguished:
- high purity with a percentage of more than 99.95%;
- technical purity, containing about 1% of impurities and additives.
Compounds of iron and silicon are most often considered as impurities. In the international standard ISO for aluminum and its alloys, a separate series is highlighted.
Aluminum grades
The technical appearance of the material is divided into certain brands that are assigned to the relevant standards, for example, AD0 according to GOST 4784-97. At the same time, high-frequency metal is included in the classification so as not to create confusion. This specification contains the following brands:
- Primary (A5, A95, A7E).
- Technical (AD1, AD000, ADS).
- Deformable (AMg2, D1).
- Foundry (VAL10M, AK12pch).
- For steel deoxidation (AB86, AV97F).
In addition, ligature categories are distinguished - aluminum compounds that are used to create alloys of gold, silver, platinum and other precious metals.
Primary aluminum
Primary aluminum (grade A5) is a typical example of this group. It is obtained by enriching alumina. In nature, metal in its pure form does not occur due to its high chemical activity. Combining with other elements, it forms bauxite, nepheline and alunite. Subsequently, alumina is obtained from these ores, and pure aluminum is obtained from it using complex chemical-physical processes.
GOST 11069 sets the requirements for primary aluminum grades, which should be noted by applying vertical and horizontal stripes with indelible paint of various colors. This material has found wide application in advanced industries, mainly where high technical characteristics are required from raw materials.
Technical aluminum
Technical aluminum is a material with a percentage of foreign impurities of less than 1%. Very often it is also called unalloyed. Technical grades of aluminum according to GOST 4784-97 are characterized by very low strength, but high corrosion resistance. Due to the absence of alloying particles on the metal surface, a protective oxide film is quickly formed, which is stable.
Brands of technical aluminum are distinguished by good thermal and electrical conductivity. In their molecular lattice, there are practically no impurities that scatter the electron flux. Due to these properties, the material is actively used in instrumentation, in the production of heating and heat transfer equipment, and lighting items.
Deformable aluminum
Deformable aluminum is a material that is subjected to hot and cold pressure treatment: rolling, pressing, drawing and other types. As a result of plastic deformations, semi-finished products of various longitudinal sections are obtained from it: aluminum bar, sheet, tape, plate, profiles and others.
The main grades of deformable material used in domestic production are given in regulatory documents: GOST 4784, OCT1 92014-90, OCT1 90048 and OCT1 90026. A characteristic feature of the deformable raw material is the solid structure of the solution with a high content of eutectic - the liquid phase, which is in equilibrium with two or more solid states of a substance.
The scope of deformable aluminum, as well as that where the aluminum bar is used, is quite extensive. It is used both in areas requiring high technical characteristics of materials - in ship and aircraft construction, and at construction sites as an alloy for welding.
Foundry aluminum
Aluminum foundries are used for the manufacture of shaped products. Their main feature is the combination of high specific strength and low density, which allows you to cast products of complex shapes without cracking.
According to its purpose, foundry brands are conditionally divided into groups:
- Highly sealed materials (AL2, AL9, AL4M).
- Materials with high strength and heat resistance (AL 19, AL5, AL33).
- Substances with high corrosion resistance.
Very often, the performance characteristics of cast aluminum products are increased by various types of heat treatment.
Deoxidation Aluminum
The quality of manufactured products is also affected by the physical properties of aluminum. And the use of low-grade grades of material is not limited to the creation of semi-finished products. Very often, it is used for the deoxidation of steel - the removal of oxygen from molten iron, which is dissolved in it and thereby increases the mechanical properties of the metal. For this process, the most commonly used brands are AB86 and AB97F.