Aluminum grades

Terms and Definitions

Aluminum grades

unalloyed aluminum – This aluminum without alloying elements in the aluminum content of not less than 99,00%, rest – impurity. Impurity – metallic or non-metallic element, present in the metal, which is not controlled by the minimum content.

refined aluminum – unalloyed high-purity aluminum (aluminum content not less 99,950%), which is produced as a result of special metallurgical treatments.

Primary aluminum – unalloyed aluminum:

which is made of alumina, usually by electrolysis, and
which has an aluminum content of at least 99,70%.

Unalloyed aluminum subdivided into marks depending on the content of impurities.

russkomu time “mark” corresponds to the English term “grade” [1].

Aluminum alloys

Aluminium alloy – this is aluminum:

which contains alloying elements,
wherein the aluminum content is higher, than any other element, and
in which, aluminum content of not more 99,00%

Alloying element – This metallic or non-metallic element, which is controlled at a predetermined interval content, to provide the specific properties of the alloy set. Typically, the alloying elements are intentionally added to the melt of aluminum.

Doped aluminum alloys is divided into.

Every aluminum alloy has its own designation, for example, AD31 abortion or miscarriage 2017. This alloy designation clearly identifies its chemical composition, including, Intervals content of alloying elements and tolerances of the maximum content of impurities. It should be noted, that sometimes, including, the standards, used the expression “alloy brand”. However, the difference between the meaning of the expressions “alloy brand” and “alloy” it is not clear.

russkomu time “alloy” corresponds to the English term “alloy” [1].

Classification of grades of aluminum

Among the grades of aluminum, they are distinguished by the method of smelting and the purpose:

brand primary aluminum
brand deformable aluminum
brand casting aluminum

Stamps primary aluminum

Primary aluminum is classified into:

aluminum of extra high purity (aluminum content is higher 99,995%)
high purity aluminum (aluminum content from 99,95 to 99,995%)
aluminum of technical purity (aluminum content from 99,00 to 99,85%)

Stamps primary aluminum is used, mainly, for melting aluminum alloys in the manufacture, wrought and cast. In this technical purity grade aluminum used for general purpose alloys. high purity aluminum marks used for the production of special alloys, for example, for aviation and astronautics. Moreover, brand high purity and extremely high purity are used in various technologies highly technical, for example, Semiconductor Manufacturing.

Stamps deformable aluminum

Major brand deformable aluminum have a purity of 99,00 to 99,85%. They are intended for manufacturing products by hot and cold metal forming, i.e – rolling, extrusion, drawing, stamping, etc.. P.

Stamps casting aluminum

Stamps casting aluminum have very limited application, mainly for the production of cast rotors of electric motors. They have a purity of 99,00 to 99,70 %.

Primary aluminum

aluminum Stamps in CCITT 11069

The main indicator of the purity of primary aluminum is the content of iron and silicon (table 1):

Primary aluminum technical grade, which is obtained by electrolysis of molten cryolite-alumina. It contains from 99,85% aluminum (up to 0,08% iron and 0,06% silicon) to 99,0% aluminum (up to 0,50% iron and 0,50% silicon).
High purity aluminum, which is produced by electrolytic refining of commercial purity aluminum. It contains from 99,995% aluminum (up to 0,0015% iron and 0,0015% silicon) to 99,95% aluminum (up to 0,030% iron and 0,030% silicon).

Particularly pure aluminum obtained by the use of sophisticated purification methods, for example, zone refining. It has a purity of at least 99,999% (the total content of all impurities does not exceed 0,001%).

Table 1 – The chemical composition of primary aluminum marks GOST 11069

For primary aluminum, which is used for the production of alloys, the total content of impurities except important role often also plays ratio of iron and silicon content. This ratio impurities affect, in particular, susceptibility to hot cracking primary aluminum, and grades and alloys, made on its basis. The ratio of iron and silicon depend on the feedstock and primary aluminum production technology.

Two ways method designation of primary aluminum

It is known, that all primary aluminum production process based on the Hall-Heroult. The main impurities smelted primary aluminum are iron and silicon. Moreover, in primary aluminum is typically present minor impurities, such as , zinc, gallium, titanium and vanadium. Normally, in international practice, the main criterion, which characterizes the chemical composition and value of primary aluminum, It is the minimum content of pure aluminum. However, in the United States a more important criterion, that reflects the value of primary aluminum, considered content of iron and silicon. This approach has established the American Aluminum Association.

Therefore, grades of unalloyed aluminum can be designated in two ways:

the minimum content of pure aluminum, for example, Al 99,70 % or
on the maximum content of silicon and iron - a Phhhh.

The letter P followed by the numbers, that indicate the maximum content of silicon and iron, eg:

R1020 - is unalloyed primary aluminum - primary aluminum stamp, not more than 0,10% silicon and not more than 0,20% gland.
R0506 - The brand of primary aluminum, not more than 0,05% silicon and not more than 0,06% gland.

Stamps aluminum in EN 576 и ISO 115

These two different approaches to estimate the properties of primary aluminum reflected in European Standard EN 576:2004. This standard specifies requirements for chemical composition of different grades of primary aluminum in accordance with the international approach, and – American approach. The provisions of EN 576 broadly in line with the provisions of the same international standard ISO 115:2003.

Table 2 It reflects an international approach, table 3 - the approach of the American Aluminum Association.

Table 2 - unalloyed aluminum with minimum Al-content specified -
Chemical composition: maximum percentage by weight

Table 3- unalloyed aluminum without the minimum aluminum content –
Chemical composition: maximum percentage by weight

Designation aluminum grades in Table 2 It has “American” kind: consists of four digits, faced with the letter P, and after them - letter, indicating a series of, for example, Р1020А:

The first two digits, XX, indicate two decimal places in the maximum silicon content: 0, XX.
The last two digits, YY, indicate two decimal places in the maximum iron content: 0, YY.
For base grades for four digits followed by the letter A.

Variations of the basic aluminum brands, i.e. having the same limits for the content of silicon and iron, but different limits for the content of other elements, designated by the letters A to replace another letter, starting with B, but other than I, O and Q.

Marks on aluminum LME

Standard mark primary aluminum, which is the subject of international trade, including, on the London Metal Exchange (LME) is a grade of aluminum with a purity 99,70% [3]. This is equivalent to American brand P1020 Primary Aluminum. This provides the maximum grade aluminum content of iron in the metal 0,20% and the maximum content of silicon 0,10% (i.e 10 silicon hundredths , 20 hundredths of iron, hence - P1020).

The metal with a low aluminum content, for example, 99,50%, It is considered to be the products of lower quality and are usually sold at a discount. The metal may be melted and mixed in a foundry with a high-grade metal, to get ingots, that meet the requirements of LME or finished casting products. The main impurities in the preparation of a high-grade metal are iron and silicon. Increasing the aluminum content above 99,70% It means essentially proportional reduction of iron and silicon content, while the content of other impurities remains practically unchanged [3].

wrought aluminum

aluminum Stamps in CCITT 4784

GOST 4784-97 comprises aluminum, are used in the manufacture of products of metal forming methods. Here the numbers say little useful:

The more zeros, the purer aluminum
aluminum without numbers (AD) – most “dirty”.

E (electrical) versions contain a reduced silicon content to improve electrical conductivity. In contrast to the Standard 11069 GOST 4784 It does not exclude a secondary aluminum, ie aluminum, obtained from scrap.

Table 4 – Stamps deformable aluminum GOST 4784-97

Stamps aluminum in EN 573-3

Table 5 – Stamps of deformable aluminum EN 573-3

aluminum foundry

Foundry aluminum brand are 1xx series of casting alloys by the International Classification of aluminum and its alloys. Although often referred to as alloys, there is no reason to attribute them to full-fledged alloys: they contain at least 99,00 % aluminum and have not formally alloying elements, However, unlike primary aluminum marks them control the ratio of iron and silicon content.

These alloy grades of the 1xx casting series are used for casting rotors of electric motors (table 6). Rotors of high pressure is usually cast in the casting machine, which are specially designed for this purpose. Typical aluminum rotor is shown in Figure 1. These brands foundry aluminum 1xx series are also used in some other cases, which do not require complex forms of castings.

Table 6 – “rotary” cast aluminum grades [4]

Figure 1 – Typical aluminum rotor of an electric motor [4]

In these rotary “alloys” set not only limits purity aluminum, but also the ratio of iron and silicon content. This ensures the formation of intermetallic particles, are less, than others adversely affect the casting properties of these “alloys”, as well as their electrical conductivity.

Since unalloyed aluminum is cheaper, than rotary alloys, there have been attempts to replace them with the primary grade aluminum during the manufacture of the rotors. for instance, primary aluminum ingots R1020 have the same cleanliness, as well as “alloy” 170.2, but without ratio control iron and silicon, and the uncontrolled content of titanium and vanadium. experience has shown, that ignoring these differences leads to a scatter of electrical conductivity characteristics and low casting properties of aluminum when casting rotors [5].

The purest "rotary" aluminum (170.1) is the most difficult to cast: it is most susceptible to shrinkage cracking.
conversely, less pure aluminum 100.1 It is pouring much easier with minimal cracking .
Purer aluminum brand, for example, 99,80% and 99,85 %, more prone to cracking when they are casting, than aluminum brand 170.1 [4].

Microstructure unalloyed aluminum

Iron and silicon

Since iron and silicon are basic and optional elements of the impurity, and because iron is very low solubility in solid aluminum, in the microstructure of all grades of aluminum – except refined, particularly pure aluminum – visible phase aluminum-iron and aluminum-iron-silicon. In the cast equilibrium state, the following phases can be present in unalloyed aluminum: FeAl_3,Fe₃unlucky_12,Fe₂Si₂Al_9.

minor impurities

minor impurities, for example, copper and manganese, They are in too small an amount, to form their own phase, but can participate in the formation of other phases. To detect them requires a high microscope resolution and sophisticated phase identification techniques [2].

The use of aluminum nelegirovanogo

Stamps refined aluminum

Refined aluminum with a purity aluminum call from 99,99 % to 99,9999 %. Abroad, the purity of such aluminum is often denoted "4N to 6N" - by the number of nines (Nother). This was prepared by special methods of primary aluminum. Refined aluminum grades are used in the following areas:

Foil for electrolytic capacitors (grade 1199)
semiconductor Manufacturing
Plates for the manufacture of flat panel displays
Pin layout in the electronics industry
Production of thin films
Production of high purity and high purity alumina powders
Electronic drives (memory disks)
For products with a smooth surface and jewelry
Production of ultrapure aluminum alloy for aerospace

Brand commercial purity aluminum

Electrical conductors: wire, twisted prvodniki, bus, transformer strips (grades 1350)
Lithographic plates (mark 1100)
Packing: aluminum foil grade (grade 1100, 1145, 1050, 1235)
Extruded tubes for food, chemical and brewing industry (brands 1050, 1060)
Heat exchangers (brands 1050, 1070, 1145)
Passive seismic protection systems. Low yield stress and high ductility are used to effectively dissipate seismic energy during earthquakes (grade 1050A)
Aluminum bottles (grades 1050A and 1070A)

Aluminum for steel deoxidation

aluminum Stamps in CCITT 295

Aluminum, which is used for steel deoxidation, as well as powders and ferroalloy production for aluminothermy also divided into stamps. Requirements for these aluminum grades sets GOST 295-98. This aluminum is produced both from virgin raw materials, and from scrap and aluminum waste. Produced ingots and pellets. For these aluminum grades characterized by a very high content of impurities – in a total amount up to 13 %.

Table 7 – Stamps aluminum Deoxidation, production of ferroalloys and aluminothermy

Sources:

Properties of Pure Aluminum / A. Sverdlin //Handbook of Aluminium: Vol.1 Physical metallurgy and Processes, ed. G.E. Davis, D.S. MacKenzie, 2003
Aluminum and Aluminum Alloys / ed. J.R. Davis – ASM International, 1993
The Aluminium Industry /James F King – Woodhead Publishing, 2001
https://www.aluminum.org/sites/default/files/aecd16.pdf
Aluminium Alloy Castings. Properties, Processes and Applications / J.G. Kaufman, E.L. Rooy – ASM International, 2004