This approach involves theoretical and experimental study on the effect of cold
working percentage on the hardening exponent (n). The important of this object deals
with relation of hardening exponent on the spring back and mechanical properties.
The materials used was aluminum alloy, which as a round specimen and compressed
in different cold working percentage. For the research the following condition are
obtained, that the hardening exponent, spring back of metal and hardness increase
with increase of cold working percentage. This explain the behavior of metal during
forming process and explain the change witch obtain in micro structure ,the hardness
and spring back of metal is directly proportional with strain hardening exponent.