classification of alloys 

Classification and designation of aluminum alloys

 

The modern international classification of deformable aluminum alloys It is a digital classification of the American Aluminum Association, introduced in 1954 year, according to which each alloy is assigned "number" of the 4-digit.

International designations aluminum alloys

  • The first digit indicates the major alloying element, which forms a series (group) of alloys with similar properties.
  • The last two digits are assigned to the next in this series alloy.
  • The second digit indicates alloy modification. for instance, alloy 6463 Alloy modification is 6063 with somewhat more rigid restrictions on the contents of certain alloying elements and impurities, such as iron, manganese and chromium, to obtain a better quality in the final surface finish, for example, when anodizing.

International and European standards

The international standard ISO 209-1 and European Standard EN 573 include, in addition to digital signage is also an additional "chemical" designation.

Table 1 – Designation of wrought aluminium alloys [1]

1xxx – technical aluminum

This series is designed for commercially pure aluminum with an aluminum content of not less than 99 %. Designations 1xxx series alloys are assigned depending on the degree of purity of aluminum and the type of impurities, the most important of which are iron and silicon. The main applications of this alloy series are electrical conductors, and chemical equipment, as distinctive properties of alloys of this series are a good conductivity and corrosion resistance.

  • The last two digits of the alloy designation indicate two digits to the right of the decimal point (comma) of the percentage of aluminum. for instance, 1050 denotes alloy, in which the aluminum content is 99,50 %.

2xxx – Aluminum alloys with copper

The main alloying element of this series is copper, alloy which provides high strength, but results in a reduced corrosion resistance.

  • These alloys have been among the first aluminum alloy of duralumin and they were named.
  • Alloy 2024 is an, probably, the best known and most widely used "airplane" alloy.
  • Currently, most of the alloys in this series have lost their former popularity, because they have insufficient corrosion resistance when working outdoors without a protective coating, as well as difficult to weld.

3xxx – Aluminum alloys with manganese

Manganese is the principal alloying element 3xxx series, increasing strength unalloyed aluminum somewhere on 20 %. The corrosion resistance and workability of these alloys is very high. The most popular series alloy - 3003. Alloys of this series is often used in construction, rain gutters at the device, roofing and cladding of buildings.

4xxx – siliceous aluminum alloys

This is a pretty exotic series of alloys has a major alloying element silicon. Copper, magnesium and beryllium may be added as additional alloying elements. The vast majority of alloys of this series are netermouprochnyaemymi, but there are exceptions. The silicon content may be as high 13,5 % for reducing the onset of melting temperature and improve yield, It is very important, since most of these alloys are used for the manufacture of wire and rod for welding and brazing.

5xxx – aluminum alloys with magnesium

In alloys series 5xxx main alloying element – magnesium,. The result is a strong, corrosion-resistant, good weldable aluminum alloys. These alloys are used for the manufacture of ship hulls and other marine equipment, wire and welded tanks. Strength of the alloys of this series is directly proportional to the content of magnesium, which can reach 6 %.

6xxx – aluminum alloys with magnesium and silicon

Alloys of this series contain magnesium and silicon from 0,2 to 1,8 % in proportions to form magnesium silicide, Mg2Si. These alloys have a good balance of corrosion resistance and strength.

  • A popular construction material is an alloy 6061, which is close to the yield strength of mild steel.
  • The vast majority of profiles made from aluminum alloy similar 6060 and 6063. All aluminum building envelopes (facades, windows and doors).

7xxx – aluminum-zinc alloys

The main alloying element of this series of alloys - zinc. The 7xxx series includes two types of alloys:

  • alloys of Al-Zn–Mg, for example, alloy 7005 and
  • alloys Al–Zn-Mg-Cu, for example, alloy 7075.

Additives to copper alloys Al-Zn–Mg, together with small amounts of chromium and manganese give the highest, which is available only for aluminum alloys. In certain alloys the tensile strength can exceed 600 MPa. Although copper and reduces the overall corrosion resistance, it improves corrosion resistance under stress.

8xxx – all other aluminum alloys

This series includes the newly developed alloys, the main alloying elements which are different from the main elements of other series or for other reasons can not be included in the "traditional" series. for instance, in this series included, including

  • lithium alloys for the aerospace industry (e.g., 8090);
  • iron alloys containing more 1 % for the manufacture of aluminum foil (eg, 8006, 8011, 8079, 8111);
  • alloys, are used for the production aluminum wires (eg, 8017, 8030, 8076, 8177).

Lithium has a significantly lower density, than aluminum (0.53 g / cm³), and its solubility in aluminum is relatively large. Therefore, it can be doped with aluminum in large quantities and provide a significant reduction in density aluminum alloy - to 10 % compared to other aluminum alloys.

Sources:

  1. TALAT Lecture 1255
  2. Aluminum and Aluminum Alloys – ASM Handbook – 1993