Basic principle of heat treatment of aluminum and aluminum alloys（1）

Annealing:

the product is heated to a certain temperature and held for a certain time, and then cooled to room temperature at a certain cooling rate. Through atomic diffusion and migration, the structure is more uniform and stable, and the internal stress is eliminated, which can greatly improve the plasticity of the material, but the strength will be reduced. 

① Ingot homogenization annealing: keep warm at high temperature for a long time, and then cool at a certain speed (high, medium, low and slow), so as to homogenize the chemical composition, structure and properties of the ingot, which can improve the plasticity of the material by about 20%, reduce the extrusion force by about 20%, increase the extrusion speed by about 15%, and improve the surface treatment quality of the material at the same time.

② Intermediate annealing: also known as local annealing or inter process annealing, it is to improve the plasticity of materials, eliminate the internal processing stress of materials, and keep them warm for a short time at a lower temperature, so as to facilitate continuous processing or obtain a combination of certain properties.

③ Complete annealing: also known as finished product annealing, it is to hold for a certain time at a higher temperature to obtain the softened structure in the state of complete recrystallization, with the best plasticity and low strength.