Aluminium–magnesium–silicon alloys

Even clusters of magnesium and silicon atoms that are only metastable dissolve only slowly, due to the high binding energy of the two elements.

However, if the cooling speed is insufficient, they also bind excess silicon, which would otherwise form coarser excretions and thus reduce strength.

EN stands for European standard, AW for aluminium wrought alloy; the number has no other meaning.

Conditions: AlMgSi can be used in two different ways through aHeat treatment can be hardened, whereby hardness and Strength rise, while ductility and Elongation at break.

Both begin with the Solution annealing and can also be used with mechanical processes (Forging), with different effects: If time passes after quenching and hot curing (so-called interim storage), then the achievable strength decreases during hot curing and only occurs later.

To prevent these negative effects, AlMgSi can be annealed after quenching at 80 °C for 5–30 minutes, which stabilizes the material condition and temporarily does not change.

Stabilization has other advantages: The material is then in a definable state, which allows repeatable results in the subsequent processing.

Otherwise, for example, the time of interim outsourcing would have an impact on theRebound at theBending so that a constant bending angle would not be possible over several workpieces.

A transformation (forging, rolling, bending) leads to metals and alloys strain hardening, an important form of increasing strength.

On the other hand, cold forming in a partially or fully cold-hardened state also increases the strength, so that both effects add up.

If, on the other hand, the cold forming takes place in the stabilized state, the achievable strength values improve.

In the latter case, they were largely responsible for the changed design of rail vehicles in the 1970s: previously, riveted pipe structures were used.

The weldable higher-strong AlMgSiCu alloys (AA6013 and AA6056) are used in the Airbus models A318 and A380 for ribbed sheets in the aircraft hull used, where through the Laser welding, weight and cost savings are possible.