Recovery Phase
The recovery phase is the process where point defects and dislocations in the crystal lattice dissolve through diffusion without forming new grain boundaries. This reduces internal residual stresses but maintains strength.
Physical-Chemical Mechanism of Action
After plastic deformation, point defects and dislocations form in the crystal lattice. During the recovery phase, these defects slowly diffuse out of the lattice without forming new grain boundaries. This leads to a decrease in internal residual stresses.
Metallurgical Relevance & Welding Risks
The recovery phase is important for reducing hardness and stress in the material structure, which improves formability and weldability. If this phase is too short or too long, unwanted properties such as increased hardness or stresses can occur, which can cause cracks.
Workshop Practice & Action Guidelines
The recovery phase should be allowed during welding and forming until internal stress is reduced. This can be achieved by sufficient cooling or by special deformation techniques. Too fast cooling can prevent the recovery phase from completing, leaving the material hard and stressed.