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Aluminium in two minutes

Properties of aluminium

Weight

The density of aluminium is 2.7 g/cm3, which corresponds to about one third of the density of steel.

Strength

Aluminium alloys have a tensile strength ranging from 70 to 700 MPa. The alloys used most often in extrusion: 150–300 MPa.

Unlike most steel grades, aluminium does not become brittle at low temperatures, instead its strength increases. At high temperatures the strength of the metal decreases. If the temperature continuously exceeds 100°C, the strength is affected to such a great extent that it must be taken into account at the designing stage.

Linear expansion

Aluminium has a relatively large coefficient of linear expansion compared with other metals. It must be taken into account in some designs.

Formability

Apart from being suitable for extrusion, aluminium can also be rolled and bent in both hot and cold condition.

Machining

Aluminium is easily worked using most machining methods – milling, drilling, cutting, punching, turning and bending. The energy input during machining is low.

Jointing

Jointing features are often built into the profile. Apart from this, there are also well-tried welding (fusion welding and Friction Stir Welding), bonding and taping methods.

Conductivity

Aluminium is a very good conductor of heat and electricity. An aluminium conductor weighs about half as much as a copper conductor with the same conductivity.

Reflectivity

Aluminium is a good reflector of both visible light and heat radiation.

Screening – EMC

Tight aluminium boxes effectively exclude or screen electromagnetic radiation.

Corrosion resistance

When aluminium reacts with the oxygen contained in the air, a very thin oxide layer is formed – only some hundredths of a µm in thickness (1 µm is one thousandth of a millimetre). This layer is very tight and provides very good protection against corrosion. If damaged, the oxide layer has the ability to rebuild itself.

During anodising the thickness of the oxide layer is increased – and the natural corrosion protection is improved.

Aluminium is very durable in neutral and moderately acid environments. In very acid and alkaline conditions the rate of corrosion is high.

Non-magnetic material

Aluminium is a non-magnetic (or actually paramagnetic) material.

Non-toxic substance

After oxygen and silicon, aluminium is the most common element in the Earth’s crust and aluminium compounds occur naturally in our food.