Recovery is the first stage of annealing process On the one hand, with higher temperature relief occurs internal efforts caused by work in cold, (residual stresses), and on the other hand, microstructural changes occurs
Recrystallization: If a previously cold deformed metal, is annealed at a temperature high enough, (temperature of recrystallization), new crystals appear in the microstructure, those that have identical composition and reticular structure that old undeformed grains
Grain growth, this occurs when annealing is continued then if recrystallization is completed
Explanation:
When a metal is plastically deformed temperatures well below that of its melting point, it is said that the metal has been cold worked Most of the energy used in this deformation is dissipates as heat, storing a small fraction as energy of deformation. The latter is accumulated in form of dislocations and defects punctual, for example: broken links and vacancies As the density increase of dislocation is not even, zones occur of higher density, which leads to cell generation
Recovery
Comprises a series of phenomena that occur at more temperatures very low, with respect to the temperature of fusion of the material, among which you can highlight:
Annihilation of specific defects
Polygonization
Drop in electrical resistivity (R)
The annihilation of specific defects consists of diffusion, by adding of heat, from vacancies to dislocations and grain borders, so manages to decrease its quantity to the number equilibrium at temperature correspondent.
Recrystallization
The driving force of recrystallization comes from the stored energy of cold work
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Recrystallization temperature corresponds to the approximate temperature of which a highly cold worked material it completely recrystallizes in one hour. Recrystallization is sensitive to changes in the temperature at which it is performed, rather than at time to temperature variations constant.
Grain growth
A process aimed at eliminating surface energy in grain boundaries. This process implies a greater chemical stability since the total energy stored in the material is reduced. If the structure of the grain limits is uniform and the energy of the limits is isotropic, then it has to do with the reduction of the grain limit area. The process is activated by adding heat to the material
