Esterer Gießerei - Stress relief annealing

According to its name, stress relief annealing is an after-treatment procedure of casts with the aim to reduce inner stress within the castings through annealing and slow cooling-down.

The heating of the material, resp. annealing, takes place – at least with steel – at a temperature between 550 and 650 degrees Celsius and is therefore under the range of austenite formation. During the subsequent slowly performed cooling process we temporarily reduce the yield strength and the maximum breaking stress. The material begins to flow plastically. The inner tensions reduce up the range of the yield strength.

Without this process the inner tensions would be released during further treatment of the part and they would lead to defaults and thus to geometric deviations.

Tensions within a cast can develop during founding or welding due to uneven cooling or through strong mechanic treatment.