Aluminum and aluminum alloys are lightweight, non-ferrous metals with good corrosion resistance, ductility, and strength. Products differ in terms of composition, grade, shape, dimensions, and features.

Alloy Forms

Aluminum alloys can be developed from one or a combination of metal forming processes.

Wrought non-heat-treatable alloys are mechanically worked after being cast and cannot be strengthened by precipitation hardening; they are hardened primarily by cold working. Working the material densifies it, adding tensile strength but lowering malleability. The wrought non-heat-treatable alloys include the commercially pure aluminum series (1xxx), the aluminum-manganese series (3xxx), the aluminum-silicon series (4xxx), and the aluminum-magnesium series (5xxx). 

Wrought heat treatable alloys are mechanically worked after being cast and can be precipitation hardened to develop quite high strength levels. Working the material densifies it, adding tensile strength but lowering malleability. These alloys include the 2xxx series, the 6xxx series, the 7xxx series, and the 8xxx series. 

Casting alloys are formed by a casting process that forms alloys either continuously or into set shapes. They include heat-treatable and non-heat-treatable alloys. Since no machining or hammering is done, the fibers in the alloys line up less evenly, allowing more workability and higher amounts of alloying elements to be added but decreasing the alloy’s strength. The major categories include the 2xx.x series, the 3xx.x series, the 4xx.x series, the 5xx.x series, the 7xx.x series, and the 8xx.x series. 

Powdered metal (PM) alloys are formed by mixing powdered metals, compacting the mixture under controlled pressure, and sintering to create a permanent form. The process is a cost-effective alternative to forging or casting.

Alloy Material Grades

Aluminum alloys come in a large variety of allow types. Some of the most common are the 7xxx, 6xxx, 5xxx, 3xxx and 1xxx series types.

• 7xxx alloys are among the highest strength alloys available. They are generally used for mission critical operations in aerospace where strength and lightweight properties are essential.
• 6xxx alloys are high/medium strength commercial alloys that offer a good range of mechanical properties and good corrosion resistance. Applications include a wide range from shop building to aerospace.
• 5xxx alloys have very good weldability and corrosion resistance to seawater and marine atmosphere. They are used in marine, automotive, railway, machinery, and construction.
• 3xxx alloys are medium strength alloys that have good workability. They also have very good corrosion resistance through the atmosphere and are used in decorative trim, cooking utensils, heat exchangers, and office equipment.
• 1xxx alloys are essentially pure aluminum and have high electrical conductivity and corrosion resistance. They are used in low/medium strength applications such as light reflectors, heat exchangers, electrical components, and chemical equipment.

Sizes and Specifications

Selecting metal alloys requires an analysis of the desired dimensions and specifications. Dimensions to consider include:

• Outer diameter (OD)
• Inner diameter (ID)
• Overall length
• Overall thickness

Other specifications of importance (based on application) include product shape, tensile strength, yield strength, melting point, conductivity, corrosion resistance, ductility, and malleability. These properties differ based on the forming method and alloy composition.

References

Capalex - Aluminum Alloys

ASM - Aluminum and Aluminum Alloys

Image credit:

Belmont Metals, Inc.