The primary objective of the annealing heat treating process is to soften a part or component. Annealing is performed by heating to a specific temperature, holding at that temperature for a specific time, then slowly cooling to room, or ambient, temperature. Temperature and time vary depending on the metal or alloy.
Many industrial metals become hard and brittle when their form or shape is changed during the manufacturing process. Examples of processes that harden and embrittle metals include drawing wire to smaller diameter, forging parts to desired shapes by hammering, and stamping sheet metal to specific shapes. Periodic annealing prevents tearing or fracture of the part in the manufacturing process by returning it to a softened condition. Once annealed, continued shaping processes can be applied to the part.
Annealing is also used to relieve internal stresses that result from manufacturing processes (stress relieve) and to refine microstructure to obtain beneficial material properties.