text: Discontinuous recrystallization is heterogeneous; there are distinct nucleation and growth stages. It is common in materials with low stacking-fault energy. Nucleation then occurs, generating new strain-free grains which absorb the pre-existing strained grains. It occurs more easily at grain boundaries, decreasing the grain size and thereby increasing the amount of nucleation sites. This further increases the rate of discontinuous dynamic recrystallization.
  Discontinuous Dynamic Recrystallization has 5 main characteristics:
  * Recrystallization does not occur until the threshold strain has been reached
  * The stress-strain curve may have several peaks – there is not a universal equation
  * Nucleation generally occurs along pre-existing grain boundaries
  * Recrystallization rates increase as the initial grain size decreases
  * There is a steady grain size which is approached as recrystallization proceeds
  Discontinuous dynamic recrystallization is caused by the interplay of work hardening and recovery. If the annihilation of dislocations is slow relative to the rate at which they are generated, dislocations accumulate. Once critical dislocation density is achieved, nucleation occurs on grain boundaries.  Grain boundary migration, or the atoms transfer from a large pre-existing grain to a smaller nucleus, allows the growth of the new nuclei at the expense of the pre-existing grains. The nucleation can occur through the bulging of existing grain boundaries. A bulge forms if the subgrains abutting a grain boundary are of different sizes, causing a disparity in energy from the two subgrains. If the bulge achieves a critical radius, it will successfully transition to a stable nucleus and continue its growth. This can be modeled using Cahn’s theories pertaining to nucleation and growth.
  Discontinuous dynamic recrystallization commonly produces a ‘necklace’ microstructure. Since new grain growth is energetically favorable along grain boundaries, new grain formation and bulging preferentially occurs along pre-existing grain boundaries. This generates layers of new, very fine grains along the grain boundary initially leaving the interior of the pre-existing grain unaffected. As the dynamic recrystallization continues, it consumes the unrecrystallized region. As deformation continues, the recrystallization does not maintain coherency between layers of new nuclei, producing a random texture.