Under what conditions does aluminum corrode

Types of aluminum corrosion

Surface corrosion in aluminum

Surface corrosion is very rare with aluminum. It only arises when the protective oxide layer of the metal becomes ineffective over a large area due to corrosive media, for example in a strongly acidic or basic environment.

In most cases, however, only punctual corrosion occurs with aluminum if passive corrosion protection is no longer provided due to damage to the surface or oxide layer.

Contact corrosion

Contact corrosion can also occur with aluminum under the right circumstances. Due to the relatively low potential of aluminum, this type of corrosion is quite common when paired with other metals. However, it can be avoided constructively.

Stress corrosion cracking

Stress corrosion cracking can occur in aluminum, depending on the respective alloy and the condition of the material. The stress limits vary from alloy to alloy and can be significantly increased by choosing the right material.

Pitting corrosion

Pitting corrosion occurs in most aluminum materials when they are exposed to electrolytic material removal in an acidic or neutral environment. In many aluminum alloys, pitting corrosion progresses very quickly.

It can be prevented if an alloy that is suitable and sufficiently resistant for the respective area of ​​application is used. Changing the ambient conditions can also help prevent pitting corrosion from occurring.

Other forms of corrosion

In rare cases, aluminum can also be affected by other types of corrosion:

  • Layer corrosion occurs with some materials under special circumstances
  • Aluminum is a material that also has a tendency to intergranular corrosion, but the right conditions must be in place for this, and not all alloys are affected to the same extent
  • Aluminum can corrode punctually if the oxide layer is damaged
Before using it under special loads, it should always be carefully checked whether the material used is sufficiently suitable and resilient enough. Otherwise a more suitable material should be chosen.

Author: Johanna Bauer Home »Building» Building Materials »Metal» Rust