Aluminium

 

Aluminium or Aluminum (American) is a chemical element with symbol Al and atomic number 13. It is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It makes up about 8% by weight of the Earth's solid surface.

aluminum

Ancient Greeks and Romans used aluminium salts as dyeing mordants and as astringents for dressing wounds; alum is still used as a styptic. In 1761, Guyton de Morveau suggested calling the base alum alumine. In 1808, Humphry Davy identified the existence of a metal base of alum, which he at first termed alumium and later aluminum . The metal was first produced in 1825 in an impure form by Danish physicist and chemist Hans Christian Ørsted. Aluminium has about one third the density and stiffness of steel. It is also known for its ability to resist corrosion due to the phenomenon of passivation. The Hall–Héroult process is the major industrial process for the production of aluminium. It involves dissolving alumina in molten cryolite, and electrolysing the molten salt bath to obtain pure aluminium metal.

Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) and the levels of these other metals are in the range of a few percent by weight.

Some of the many uses for aluminium metal are in:

  • Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, etc.) as sheet, tube, castings, etc.Packaging (cans, foil, etc.)
  • Construction (windows, doors, siding, building wire, etc.).
  • A wide range of household and sporting goods, from cooking utensils to baseball bats, watches, camping gear.
  • Street lighting poles, sailing ship masts, walking poles, etc.
  • Outer shells of consumer electronics, also cases for equipment e.g. photographic equipment

Aluminium is theoretically 100% recyclable without any loss of its natural qualities.

Aluminum Alloy Designation System

A system for designating wrought aluminum and wrought aluminum alloys was established by the Aluminum Association. Specific limits for chemical compositions to which conformance is required are provided by applicable product standards.

Wrought aluminum and aluminum alloy designation system

A system of four-digit numerical designation is used to identify wrought aluminum and wrought aluminum alloys. The first digit indicates the alloy group as follows:

, 99.00 percent minimum and greater 1xxx
grouped by major alloying elements:
Copper (Cu) 2xxx
Manganese (Mn) 3xxx
Silicon (Si) 4xxx
Magnesium (Mg) 5xxx
Magnesium and Silicon (Mg and Si) 6xxx
Zinc (Zn) 7xxx
Other elements 8xxx
Unused series 9xxx

Unified numbering system (UNS)

The Society of Automotive/Aerospace Engineers (SAE) and the American Society for Testing of Materials (ASTM) have jointly developed a numbering system to identify metal and alloy systems of "commercial standing".

This numbering system (UNS) consists of a six digit number (code) to identify each alloy. For wrought aluminum alloys this code always begins with an A and appears as follows: Axxxxx (digit) 123456.

The second digit indicates whether the alloy is bare or clad by indicating a 9 for bare and an 8 for clad. The following four digits (3-6) are the registered alloy designation. For example, A92024 would be the UNS identification for bare 2024 while the alclad alloy would be identified as A82024.

Technical Info Temper Designation System

The established temper designation system is used for all forms of wrought and cast aluminum and aluminum alloys except ingot. It is based on the sequence of basic treatments used to produce various tempers. The temper designation follows the alloy designation with the two separated by a hyphen. consist of a letter while the subdivisions of those basic tempers are indicated by one or more digits following those letters. Both the and the have such subdivisions.

The system is designed to set down specific sequences of fabrication processes, but only those operations that are recognized as significantly influencing the characteristics of the product are involved. Should some other variation of the same sequence of basic operations be applied to the same alloy, resulting in different characteristics, then additional digits will be added to the numerical designation.