The main elements used as alligants to form aluminum alloys of industrial use are magnesium (Mg), manganese (Mn), copper (Cu), silicon (Si), zinc (Zn).
Each of these elements gives the alloy specific properties; They are added to the aluminum one alone (binary alloys), two of them (ternary alloys), three of them (quaternary alloys).
These few notes will not deal with foundry alloys, as they are not traded by our company.
Aluminum alloys are conventionally divided into "Series" according to their chemical composition, as described below.
1000 Series: (pure aluminum - at least 99%); the alloys of this group are characterized by excellent corrosion resistance, high thermal and electrical conductivity, good machinability, rather low mechanical properties.
Mechanical properties can be increased, within low limits, by hardening through cold coining.
The main applications include chemical plants, reflective bodies, heat exchangers, electrical conductors and capacitors, architectural and decorative applications.
Series 2000: (avional); the main alloy element is copper; for some alloys of this serie magnesium and manganese are added.
These are alloys which must be heat treated to reach the required mechanical properties (solubilization, hardening and aging to develop mechanical working values); after heat treatment, they develop mechanical characteristics similar to those of carbon steels.
Their corrosion resistance is less than the one of other aluminum alloys; for this reason, in critical applications, they need specific protection systems.
They are used for parts and structures which require high resistance / weight ratios (aircraft wheels and vehicle structures, aerospace structures, car control arms) for operating temperatures up to about 150 ° C.
They are characterized by excellent machining workability and (except for alloy 2219) limited weldability.
5000 Series: (peralluman); the main element of this serie is magnesium.
These are alloys where mechanical properties can be increased just by cold rolling or coining, but can not be increased by heat treatment; the mechanical properties are generally less than the ones of the 2000 series alloys.
Corrosion resistance is high, even in marine environments.
They have good weldability.
Series 6000: (anticorodal); The main alloy elements are silicon and magnesium.
These are alloys which need an heat treatment; after heat treatment can be reached mechanical properties, generally lower than those of the 2000 series alloys.
They have good formability, machining workability and weldability.
They are used for architectural applications, motorcycle and bicycle frames, and welded structures.
Serie 7000: (ergal); The main element added is zinc, generally with magnesium additions.
These alloys must be heat treated; after heat treatment they reach the highest mechanical properties among the aluminum alloys.
The alloys with the best mechanical properties may show stress corrosion cracking; Specific "stabilized" heat treatment procedure have been developed in order to eliminate this problem.
They have good machining workability and, in most cases, poor weldability.
They are used for aeronautical structures and in the automotive industry for highly stressed parts.