There are over 1000 registered aluminum alloy grade numbers in the world. Each grade has different status, namely obvious difference in strength, hardness, corrosion resistance, machinability, weldability and ornamental property. It is hard and unnecessary to satisfy all the aforesaid requirements when you select aluminum alloy. Set the order of priority according to requirements in terms of product's performance, application environment and working process, select material properly and control cost reasonably under the precondition that the performance of product must be guaranteed.

Many customers pay more attention to the hardness of aluminum material. Hardness is directly related with chemical composition of alloy. Different grades vary in hardness. The hardness declines gradually in the order from 7xxx series, 2xxx series, 4xxx series, 6xxx series, 5xxx series, 3xxx series and 1 grade series.

Strength is an important factor to be considered in product design, especially when aluminum alloy component is used as structural unit, proper alloy should be chosen according to pressure load. Pure aluminum has the lowest strength while 2××× series and 7××× series aluminum alloy has the highest strength. To some extent, strength and hardness have positive correlativity.

Corrosion resistance includes resistance against chemical corrosion, electrochemical corrosion, stress corrosion, etc. Generally, pure aluminum-grade 1 has the highest corrosion resistance; grade 5 has good performance, which is followed by 3××× series and 6××× series; 2××× series and 7××× series have bad performance. In terms of corrosion resistance, select aluminum material according to its working environment. If aluminum alloy with high strength is used in corrosive environment, various anti-corrosion alclad materials have to be employed.

Processability includes shaping property and machinability. Shaping property is correlative with status; generally material with high strength is not easy to be shaped. If the grade number of aluminum alloy is determined, the strength at different statuses has to be considered. If aluminum material is to be bent, drawn or punched, complete annealing material has the best performance in shaping while material under heat treatment has the worst performance. The machinability of aluminum alloy is highly correlative with composition of alloy; generally the alloy with high strength has relatively high machinability while the alloy with low strength has lower machinability. If the alloy is used to produce mould or mechanical part, which requires machining, the machinablity of alloy is an important factor to be considered.

It is not a problem to weld most of aluminum alloys; some 5××× series aluminum alloy is specially designed for welding. It is relatively hard to weld some 2××× series and 7××× series aluminum alloys.

If aluminum material is applied to decoration or some special case, its surface must be anodized or finished to obtain corresponding color and surface texture. In this case, its ornamental property is an important factor to be considered. Generally, material with high corrosion resistance has excellent performance in anodizing, surface treatment and finishing.

Besides the aforesaid properties, you should take electrical conductivity, wearability and heat resistance into consideration while selecting material.