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.
