Aluminium–magnesium–silicon alloys

Aluminium–magnesium–silicon alloys (AlMgSi) are aluminium alloys—alloys that are mainly made of aluminium—that contain both magnesium and silicon as the most important alloying elements in terms of quantity. Both together account for less than 2 percent by mass. The content of magnesium is greater than that of silicon, otherwise they belong to the aluminum–silicon–magnesium alloys (AlSiMg).

AlMgSi is one of the hardenable aluminum alloys, i.e. those that can become firmer and harder through heat treatment. This curing is largely based on the excretion of magnesium silicide (Mg₂Si). The AlMgSi alloys are therefore understood in the standards as a separate group (6000 series) and not as a subgroup of aluminum-magnesium alloys that cannot be hardenable.

AlMgSi is one of the aluminum alloys with medium to high strength, high fracture resistance, good welding suitability, corrosion resistance and formability. They can be processed excellently by extrusion and are therefore particularly often processed into construction profiles by this process. They are usually heated to facilitate processing; as a side effect, they can be quenched immediately afterwards, which eliminates a separate subsequent heat treatment.