Aluminum alloys: categories and classes

 

Below is the international classification of aluminum alloys, as well as the designation system – International and European.

See. also Applications of aluminum

Classification

Aluminum alloys are classified, identify and distinguish in several ways:

  • by Category - Treatment Methods, deformable and foundry;
  • by class - hardened by heat treatment or cold working;
  • by series - by main alloying elements (copper, manganese, silicon, magnesium,, magnesium-silicon, zinc, iron, tin and others);
  • for alloying systems - for combinations of the main alloying elements with other alloying elements;
  • chemical composition - the content of alloying elements and impurities in series and systems.

Categories: Wrought & Foundry

Aluminum alloys fall into two main categories:

  • wrought
  • foundry.

wrought

Wrought alloys are designed for different types of hot forming and, rarely, in cold states:

  • rolling
  • extrusion (pressing)
  • forging
  • punching
  • hood
  • drawing.

For each treatment pressure developing alloys, which are optimal for these treatments.

Foundry

The main difference between casting alloys from wrought is, that they have a considerably higher content of alloying elements. Particularly high levels of a silicon - nominal content of 4 to 17 %.

Casting alloys used for manufacturing aluminum castings using various molding methods, including:

  • sand casting;
  • chill casting;
  • low pressure casting;
  • injection molding.

Classes: by way of hardening

Each category - wrought alloys and casting alloys - further subdivided according to the main mechanism of strengthening – improve mechanical properties, as well as other useful properties.

thermally reinforcing

Many alloys react to the hardening heat treatment, which is based on the dependence of the phase solubility temperature. This heat treatment includes the following operations:

  • solution treatment (heating for hardening)
  • quenching
  • precipitation of hardening phases (aging)

Alloys with the hardening mechanism, as a deformable, and casting, called heat-reinforcing.

Nagartovyvaemye

A large number of other wrought alloys, instead of relying on thermal hardening strain hardening. Strain hardening is achieved by hardening the reinforcing, which occurs when cold plastic deformation – work hardening – aluminum products, usually in combination with various annealing regimes.

Thermally neuprochnyaemye casting alloys

Casting alloys, usually, are not subjected to deformation processing due to low plastic properties. Moreover, Some of them are well and thermally reinforcing. They are used in the as-cast condition without heat treatment or thermally modified states, are not linked to phenomena of dissolution and release of hardening phases.

Series: by main alloying elements

Series - a group of alloys, wrought and cast, are combined on the main alloying elements. In this division is based is widely recognized in the world of the American system of aluminum alloy designations.

Wrought alloys and their designations

International notation wrought alloys based on the American system of notation, which it was developed in the 1950s.

This system uses the designation, which consist of four digits. The numbers on the spot "X" is used for the units within the series alloys.

  • 1xxx - Technically pure aluminum with controlled chemical composition. for instance, aluminum 1050.
  • 2xxx - main alloying element is copper, although other elements, such as magnesium, They may also be present. Widely used in aircraft, due to their high strength (yield strength up to 455 MPa). examples - 2014 and 2024.
  • 3xxx - Manganese, It is the main alloying element. Used as a general purpose alloy construction and a variety of consumer products, including aluminum cans for soft drinks and beer. example – 3105.
  • 4xxx - main alloying element is silicon. Used in welding rods and wires, as well as sheets for brazing.
  • 5xxx - main alloying element is magnesium. It is used in ship hulls, ladders and other products, are exposed to the marine atmosphere. example – 5252.
  • 6XXX - The main alloying elements are magnesium and silicon. Usually used for building profiles and automotive parts. examples - 6060 and 6063.
  • 7xxx - main alloying element is zinc, although other elements, such as copper, magnesium,, chromium, and zirconium, They may also be present. Used in load-bearing elements of the aircraft and other high structures and products. This series is the strongest aluminum alloys with a tensile strength of more than 500 MPa. Example - 7075.
  • 8xxx - Various main alloying elements. 8xxx series alloys may contain appreciable quantities of tin, lithium and / or iron.
  • 9xxx: Reserved for future use.

Wrought alloys, which are thermally hardening, They include 2xxx series alloys, 6xxx, 7xxx and some alloys of series 8xxx. Various combinations of alloying elements and hardening mechanisms, which are used for wrought alloys, are shown in Table 1.

Table 1 - Classification of wrought aluminum alloys
by the mechanism of their hardening [1]

Classification of aluminum alloys according to the mechanism of hardening

 

strength levels, which is achieved in the various classes of wrought alloys, are shown in Table 2.

Table 2 - Strength levels of various wrought aluminum alloys [1]
Levels strength wrought aluminum alloys of different batches

Casting alloys and their designations

For foundry alloys used notation of three digits, followed by a kind of "decimal". Decimal .0 in all cases refers to the limits of casting alloys. decimals .1 and .2 refer to the chemical composition of finished bars.

  • 1xx.x - Technically pure aluminum with controlled chemical composition, including impurities. It used for the manufacture of rotors of electric motors.
  • 2xx.x - main alloying element is copper. Other alloying elements may also be present.
  • 3xx.x - main alloying element is silicon. Further alloying elements may be copper and magnesium. 3hh.h series alloys are about 90 % all shaped aluminum castings.
  • 4xx.x - main alloying element is silicon.
  • 5xx.x - main alloying element is magnesium.
  • 6xx.x - Not applicable.
  • 7xx.x - main alloying element is zinc. Further alloying elements are copper and magnesium.
  • 8xx.x - main alloying element is tin.
  • 9xx.x - Not applicable.

By thermally reinforcing alloys are casting alloys series 2xx, 3xx and 7xx.

strength levels, which is achieved in the various classes of casting alloys, are shown in Table 3.

Table 3 – Strength levels of various casting alloys [1]

Levels of different strength casting aluminum alloying systems

doping system

As can be seen above, Some series aluminum alloys, wrought and cast, They include one, two or three different alloying system.

These doping system may include only the main alloying elements, or one or more additional alloying elements.

Systems doping wrought alloys

  • 2ххх - Al-Cu, Al-Cu-Mg, Al-Cu-Mg-Si, Al-Cu-Li
  • 3xxx - Al-Mn
  • 4xxx – Al-Si
  • 5xxx – Al-Mg
  • 6xxx – Al-Mg-Si
  • 7xxx – Al-Zn, Al-Zn-Mg, Al-Zn-Mg-Cu
  • 8xxx – Al-Fe, Al-Fe-Ni, Al-Li-Cu-Mg

casting alloys alloying system

  • 2xx - Al-Cu, Al-Cu-Ni-Mg, Al-Cu-Si,
  • 3xx - Al-Si-Cu, Al-Si-Cu-Mg, Al-Si-Mg
  • 4xx - A el-If
  • 5xx – Al-Mg
  • 7xx – Al-Zn
  • 8xx – Al-Sn

Chemical composition

Inside the series and aluminum alloys doping systems differ in their chemical composition, that is, the content of various alloying elements, as well as impurities.

The nominal chemical compositions of typical wrought alloys - wrought and cast are shown in Tables 4 and 5. It should be noted, In these tables, it represented only a small fraction of the total number of aluminum alloys. The international registration list there are more than 500.

Wrought alloys

Table 4 - Product types and nominal chemical composition
thermally hardened wrought aluminum alloys [1]

Typical products of the thermally deformable hardenable aluminum alloys

Table 5 - Product types and nominal chemical composition
nagartovyvaemyh deformable aluminum alloys

Typical products of wrought aluminum alloys nagartovyvaemyh

Casting alloys

Table 6 - molding and nominal chemical composition
thermally hardenable casting aluminum alloys

Methods for molding the thermally hardenable casting aluminum alloys

Table 7 - molding and nominal chemical composition
thermally neuprochnyaemyh casting aluminum alloys

Methods for thermally molding neuprochnyaemyh casting aluminum alloys

The European designation system

Wrought alloys

The European system of designations of deformable aluminum alloys based on the "American" system of four digits with the addition of a few letters in front of them, for example, EN AW-6060. Here EN stands for "European standard", AW - «wrought aluminum". The numbers in this notation corresponding international registration alloy system wrought alloys.

Casting alloys

The European designation system for cast aluminum alloys is as follows:
EN AC-xxxxx, Where:

  • EN - European standard;
  • A - aluminum;
  • C - foundry;
  • xxxxx - five digits or chemical symbols.

Example: EN AC-42000 or EN AC-Al 7SiMg

digital signage

The first number designates one of four groups (series) for the main alloying elements:

  • Copper (Cu) - 2xxxx
  • Silicon (Si) - 4xxxx
  • Magnesium (Mg) - 5xxxx
  • Цинк (Zn) – 7xxxx

The second number indicates the base alloy within the group (series):

  • 21xxx - AlCu
  • 41xxx – AlSiMgTi
  • 42xxx – AlSi7Mg
  • 43xxx – AlSi10Mg
  • 44xxx – AlSi
  • 45xxx – AlSi5Cu
  • 46xxx – AlSi9Cu
  • 47xxx – AlSi(Cu)
  • 48xxx – AlSiCuNiMg
  • 51xxx – AlMg
  • 71xxx - AlZnMg

third, the fourth and fifth digits indicate:

  • The third digit – modification of the base alloy
  • Fourth number - usually zero
  • The fifth digit - zero for general purpose alloys, and any figure for aerospace alloys

chemical designation

  • Al + space
  • Symbol main alloying element
  • Other alloying elements (no more than four elements) in order of content in the alloy; if the content is the same - in alphabetical order.

A source:

  1. Aluminum and Aluminum Alloys. Introduction and Overview / J.R. Davis – ASM International, 2001