What are the properties of different grades of deformed aluminium alloys after oxidation?

The different grades of deformed aluminium alloys have different compositions, heat treatment processes and corresponding processing forms, and therefore have different anodising properties. According to the aluminium alloy family, they range from pure aluminium of the lowest strength 1xxx series to aluminium-zinc-magnesium alloys of the highest strength 7xxx series. There are two main types of aluminium alloys used in industry, namely deformed aluminium alloys and cast aluminium alloys. Today we will focus on the characteristics of the different grades of deformed aluminium alloys after oxidation.

1xxx series aluminium alloys, also known as "pure aluminium", are generally not used for hard anodising. However, it has very good properties in bright anodising and protective anodising.

2xxx series aluminium alloys are also known as "aluminium-copper-magnesium alloys". As the Al-Cu intermetallic compound in the alloy is easily dissolved during anodising, it is difficult to produce a dense anodised film, and its corrosion resistance is even worse during protective anodising.

The 3xxx series aluminium alloy, also known as "aluminium-manganese alloy", does not reduce the corrosion resistance of the anodic oxide film, but due to the texture of the Al-Mn intermetallic compound, it will make the anodic oxide film appear grey or grey-brown.

4xxx series aluminium alloys are also known as "aluminium-silicon alloys", as this alloy contains silicon, it will make the anodic oxide film grey, the higher the silicon content, the darker the colour. Therefore, it is not easy to anodise.

The 5xxx series aluminium alloy, also known as the "Almax alloy", is a more versatile aluminium alloy, with good corrosion resistance and weldability. This series of aluminium alloys can be anodised, but if the magnesium content is high, the brightness is not sufficient. Typical aluminium alloy grades: 5052.

The 6xxx series aluminium alloys, also known as "aluminium-magnesium-silicon alloys", are particularly important in engineering applications and are mainly used for extrusion profiles. The strong 6061 and 6082 alloys cannot be anodised with more than 10μm, otherwise the anodised film will be light grey or yellow-grey and its corrosion resistance is significantly lower than that of 6063 and 6463.