Basic types of corrosion of aluminum and aluminum alloys

December 15, 2024

1. Point corrosion

Point corrosion, also known as pitting corrosion, is a localized form of corrosion that occurs on metal in the form of needle like, point like, or hole like structures. Point corrosion is a unique form of anodic reaction, which is a self catalytic process. The conditions created by the corrosion process inside the point corrosion pores are both conducive and sufficient to maintain the continuation of corrosion.

2. Uniform corrosion

In solutions such as phosphoric acid and sodium hydroxide, the oxide film on aluminum will dissolve and undergo uniform corrosion, with a uniform dissolution rate. The increase in solution temperature and solute concentration promotes the corrosion of aluminum.

3. Crevice corrosion

Gap corrosion is a type of localized corrosion. Metal components in electrolyte solutions, due to the formation of gaps between metals or between metals and non metals, have a width sufficient to allow the medium to penetrate and remain in a stagnant state, resulting in intensified corrosion inside the gaps, which is called gap corrosion.

4. Stress Corrosion Cracking (SCC)

SCC of aluminum alloys was discovered in the early 1930s. The damage that occurs in metals under the combined action of stress (tensile stress or internal stress) and corrosive media is called SCC. The characteristic of SCC is the formation of corrosion mechanical cracks, which can develop along grain boundaries or propagate through grains. Due to the fact that crack propagation occurs within the metal, it can significantly reduce the strength of the metal structure, and in severe cases, sudden damage can occur.

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