The 6xxx series of aluminum alloys contain both magnesium and silicon, which creates a quasi-binary section with the Mg2Si phase of the magnesium-silicon system. This allows for excellent precipitation hardening capabilities, resulting in moderately higher strengths compared to non-heat-treatable alloys, while also providing generally excellent corrosion resistance.
Alloys in the 6xxx series are particularly well-suited for extrusion, making them a popular choice for creating complex shapes like multihollow or finned designs. They are also easily joined using a wide range of commercial processes.
Similar to the 2xxx series, some natural aging occurs shortly after the solution heat treatment of 6xxx alloys. Therefore, forming operations should be scheduled promptly after quenching to optimize their properties.