Stress relief annealing

Stress relief annealing reduces internal stresses in a workpiece.

Especially in metallic workpieces, stresses can occur in the material, for example due to uneven cooling during thermal processing methods such as casting, welding, forging or laser sintering, but also during heavy mechanical processing such as milling, turning or deep drawing. To prevent unwanted deformation during further processing or subsequent heat treatments, these stresses must be reduced.

To do this, the workpiece is brought to a suitable annealing temperature (below the start of austenite formation, in the case of steel usually below 650°C) and held at this temperature for a long time. This reduces the yield strength and maximum tensile strength of the material. To put it simply, the resulting softer material is caused to flow plastically by the existing stresses, and the stresses are reduced. Subsequent slow and uniform cooling ensures that no new stresses build up which could deform or damage the workpiece.