Rekrystalizáció

Rekrystalizáció is a metallurgical process used to refine the grain structure of a metal or alloy. It is a form of heat treatment where the material is heated to a specific temperature, held there for a period, and then cooled. This process causes the formation of new, strain-free grains within the metal, replacing the deformed or fractured grains that existed prior to the treatment.

The driving force for recrystallization is the stored energy within the deformed metal. When a metal is plastically deformed, such as through cold working, its internal energy increases due to the formation of dislocations and lattice defects. Heating the metal provides the thermal energy necessary for atoms to migrate and rearrange themselves, leading to the formation of new, low-energy grain boundaries and a reduction in stored energy.

Key parameters influencing recrystallization include temperature, time, and the amount of prior deformation. Higher temperatures and longer holding times generally promote recrystallization. A certain minimum amount of prior deformation is also required; if the deformation is too low, recrystallization may not occur. The cooling rate after recrystallization can also influence the final grain size and properties of the material.

Recrystallization is a crucial process for improving the ductility and toughness of cold-worked metals, making them easier to further process or use in applications. It can also help to reduce internal stresses and improve electrical conductivity. The resulting microstructure consists of equiaxed, strain-free grains, which contribute to a more homogeneous and desirable set of mechanical properties.