By alloying with these other elements, the properties of aluminum such as strength, density, workability, electrical conductivity and corrosion resistance are enhanced.
During aluminum alloy processing, three different types of aluminum alloys are produced depending on their properties and treatments: industrially pure aluminum alloys, heat treatable aluminum alloys, and non-heat treatable aluminum alloys.
Each type of aluminum alloy can then be further subdivided and classified according to its primary alloying element. This is accomplished by assigning each type of alloy a four-digit number to help classify it, where the first digit indicates the general category (or series).
1. Industrial Pure Aluminum: Alloys consisting of aluminum with a purity of 99% or greater.
1xxx Series: Provides excellent corrosion resistance, excellent workability, and high thermal and electrical conductivity. This series is commonly used for transmission lines connecting to the U.S. National Grid.
2. Heat Treatable Aluminum:
Alloys that are strengthened by extreme heating and cooling processes. The alloy is heated to a specific point to evenly distribute the elements and then quenched (rapidly cooled) to freeze it in place.
2xxx Series: Copper is the main alloying element. These alloys offer a good combination of high strength and high toughness. Typically used in aircraft production.
6xxx series: Silicon and magnesium are the main alloying elements. These alloys are versatile, heat treatable, moldable, weldable, strong and corrosion resistant. Typically used in automotive production.
7xxx Series: Zinc is the primary alloying element with small amounts of magnesium, copper or chromium added for strength. These alloys are heat treatable and extremely strong. Commonly used in the commercial aerospace industry.
3. Non-Heat Treatable Aluminum:
Alloys that are strengthened by a cold working process. The cold working process "works" the metal at the rolling or forging stage and creates dislocations in the atomic structure of the metal to increase its strength.
3xxx series: Manganese is the main alloying element, with small amounts of magnesium usually added. These alloys have medium strength and good workability. They are commonly used in aluminum beverage cans and cookware.
4xxx Series: Silicon is the main alloying element. These alloys have a low melting point but are not brittle. Typically used in welding wire and structural applications.
5xxx Series: Magnesium is the primary alloying element. These alloys have medium to high strength, good weldability and corrosion resistance in aquatic environments. Typically used in building construction and marine applications.