Alumentary: Galvanic Corrosion in Aluminum

Galvanic corrosion is a process in which two different metals come into contact in a conductive liquid. In this process, the less noble metal corrodes at an accelerated rate, while the more noble metal is protected.

In fastening applications, such as screw connections, this can lead to material loss or loosening.

Our high-strength Aludrive® aluminum screws are manufactured from the AA-6056 (AlMgSiCu) alloy. In the context of galvanic corrosion, however, the question arises as to what influence the alloy composition has on this process.

In the joint, aluminum is the less noble material, which consequently acts as the anode and the preferred corroding partner. However, the other components of the alloy do have an influence on this.

Magnesium and silicon have a largely neutral effect on corrosion resistance, while the copper content increases strength. At the same time, the oxide layer—which often forms on aluminum—protects the surface and slows down electrochemical reactions.

The key factor for AluDrive screws is therefore the overall system: the composition of the material and the environmental conditions. When properly designed, galvanic corrosion in AA-6056 is thus easily controllable (even without coatings).