Hot Deformation and Dynamic Restoration

The processes of microstructural evolution during hot deformation are reviewed. These include dynamic recovery and dynamic recrystallization, where the latter occurs via several different mechanisms such as classical nucleation and continuous geometric rearrangement. Dislocations typically adopt cellular or subgrain structures thanks to rapid dynamic recovery. Constitutive descriptions of mechanical behavior such as the Zener-Hollomon equation are discussed because of the definite relationship between subgrain size and flow stress, for example. Texture development during hot deformation is often distinct from cold deformation because it is affected by both the concurrent microstructural evolution and by changes in deformation mechanisms. The latter includes disappearance of twinning at high temperature and the appearance of new slip systems such as non-octahedral slip in cubic metals. Processes of microstructural evolution in minerals and rocks are closely related to those in metals.