Which alloys of aluminium sheets can be anodized

Although anodizing is an advanced process, not all alloys of aluminum sheets are suitable to be anodized. Anodized plates of some grades are poor in color evenness. 3xxx sheets are among them. In some cases 3000 series aluminium plates like 3003 are anodized, but the film is not so bright as that of other alloys, and 3003 colored anodized aluminum sheets has a poorer appearance in color. The more frequently applied series in anodizing process include 4xxx, 5xxx, 6xxx and 7xxx.

4××× series aluminum sheets are aluminum alloys with silicon as the main alloy element, containing about 5% silicon, most of which are heat-treated non-strengthened aluminum alloys. Only alloys containing copper, magnesium and nickel can be welded and heat-treated to strengthen the alloy. The 4 series aluminum plates has a low melting point, good melt fluidity, excellent wear resistance, and high temperature resistance. After anodizing and coloring, it becomes dark gray, so it is suitable for use as building materials and manufacturing decorative parts.

5xxx aluminium sheets contain 3% to 5% magnesium, making it the lightest of all series. It boasts medium hardness, good corrosion resistance and a wide range of application. Because the 5 series aluminum plates has excellent anodizing characteristics, the notebook case made of 5xxx anodized aluminium sheets has the characteristics of fashion, vivid color, strong anti-scratch ability, anti-fingerprint, anti-perspiration corrosion, lightness and durability. They can also be used in construction fields such as blinds.

The 6 series aluminum alloy mainly contains two elements of magnesium and silicon. It combines the advantages of the 4 series and 5 series aluminum plates. It has excellent welding performance and corrosion resistance, and the surface is very smooth after processing, and it is easy to anodize and color. Series 6 anodized aluminum plates are a high-quality material for mobile phone cases.

The 7 series aluminum-zinc-magnesium sheet is a super hard heat-treatable alloy, also an aviation aluminum plate with good wear resistance. Scratch-resistant and corrosion-resistant, 7xxx anodized aluminum plates prove to be an ideal raw material for high-end electronic product housings.