Aluminium is lightweight, strong, recyclable, corrosion-resistant, and an essential part of daily life.
Aluminium all around us
Comprising a little over 8% of the earth’s crust, aluminium is the most abundant metal on the planet. It is the third most common element after oxygen and silicon.
In our lifestyles and built environment, aluminium products are just as abundant. Since its commercial production began little more than a century ago, aluminium has become the material of choice for a diverse range of applications and utilities.
What are the properties of aluminium?
Aluminium’s intrinsic properties have contributed to its popularity and varied uses.
Lightness: Its specific weight is 2.7 g/cm3
, which is one-third that of steel. In vehicles, aluminium reduces unnecessary weight and therefore fuel consumption.
Strength: Aluminium’s strength can be adapted to the application required by modifying the composition of its alloys. Certain alloys are as strong as steel.
Corrosion-resistance: Naturally generating a protective oxide coating, aluminium is particularly useful for protection and conservation.
Conductivity: Twice as good a conductor of heat and electricity as copper (based on weight), aluminium is now playing a major role in power transmission lines.
Ductility: Its low density and melting point allow aluminium products to be formed up until the last stages of a product design.
Reflective: As a reflector of heat and light, aluminium is suitable for such applications as solar technology and rescue blankets.
Impermeable and odorless: Releasing no taste or toxins, aluminium is ideal for food and pharmaceutical packaging.
Recyclability: Aluminium is 100% and infinitely recyclable with no deterioration in quality.
Sourced from bauxite ore, the material is refined into aluminium oxide trihydrate (alumina) using the Bayer process, and then reduced via a smelting process into metallic aluminium. Up to four tons of bauxite are needed to produce one ton of aluminium metal.
Once formed, aluminium is alloyed with other materials, usually iron, silicon, zinc, copper and magnesium, to create metals with different properties. The type of alloy is designated with a serial number. For example, 1,000 series alloys comprise almost pure aluminium, while 7,000 series denote a zinc alloy.
In its alloy form, aluminium can be processed in a number of ways. Usually it is extruded, cast or rolled.
Extrusion: A solid aluminium cylinder called a billet (available in a variety of alloys, pretreatments and dimensions), is heated and squeezed through a die with a shaped opening to create a desired profile. Extrusions are widely used in construction, road and rail applications.
Casting: Using either sand casting or die casting techniques, the aluminium is shaped according to a mold.
Rolling: Aluminium passes through a hot-rolling mill and is then transferred to a cold-rolling mill, which can gradually reduce the thickness of the metal down to as low as 0.05 mm. Rolled products are categorized as either foil (less than 0.2 mm thick), sheet (0.2-6 mm), or plate (thicker than 6 mm).
Aluminium and recycling
Fully recyclable with no downgrading of quality, aluminium is the most cost-effective material to recycle. In fact, 75% of the aluminium produced since its discovery is still in use today.
Using aluminium, industries can attain their overall recycling targets. In parallel, the aluminium industry is also constantly developing and refining its recycling processes.
Find out more about recycling at Constellium
Did you know?
Aluminium is so called because it is a base of “alum,” which in turn is derived from the Latin for “bitter salt.”
Aluminium is the 3rd most common element on Earth after oxygen and silicon.
It is possible to recycle and resell a discarded aluminium can in just 60 days.
Aluminium was once considered to be a precious metal, more valuable even than gold. It is said that Napoleon III, Emperor of France once gave a banquet where the most honored guest were given aluminium cutlery, while everyone else had gold.
Aluminium is the second most plentiful metallic element on earth; an estimated 8.3% of the earth crust is composed of aluminium.