annealingregimes

Annealing regimes refer to the distinct temperature–time profiles used during annealing that produce characteristic changes in the microstructure and properties of solids. In metals and alloys, these regimes are commonly described in terms of recovery, recrystallization, and grain growth, each representing a different dominant mechanism as temperature and time increase. The specific regimes realized depend on material state (such as dislocation density and prior deformation), alloying elements, atmosphere, and heating or cooling rates.

Recovery occurs at relatively modest temperatures where dislocations rearrange and annihilate, relieving internal stresses without substantial changes to grain size. This can lead to a reduction in hardness and some improvement in ductility, with little alteration of the overall grain structure. Recrystallization follows when the stored energy from deformation provides a driving force for nucleation and growth of new, defect-free grains. The material becomes softer and more ductile as new grains replace heavily deformed ones, and the onset and rate of recrystallization depend on composition, deformation, and annealing conditions.

Grain growth can occur if the temperature remains high or time is extended after recrystallization, reducing grain boundary area. This typically increases grain size, which can improve high-temperature creep resistance but often lowers strength and hardness at room temperature.

Non-isothermal and continuous annealing describe profiles where temperature is varied or ramped in industrial processes. The choice of regime aims to tailor properties such as strength, ductility, hardness, and residual stress to the application's requirements.