Stress relief annealing serves to reduce internal stresses (= residual stresses) in the workpiece. For steel, it is usually carried out in a temperature range of 550 to 650°C – i.e. below AC1, followed by slow cooling. Particularly during welding, internal stresses arise in the workpiece – due to uneven heating and cooling – which lead to distortion in subsequent processes. Furthermore, welding produces coarse-grained austenite, which in itself weakens the welded joint. To avoid these undesirable effects, stress-relief annealing is carried out.
Internal stresses can lead to cracking in later use – and thus possibly to premature component failure. Stress relief annealing is therefore also important with regard to the service life guarantees to be given.
The strength of the steel (i.e. the base material) is not changed by stress relief annealing. However, a drop in hardness must be expected in the area of the weld seam.
For quenched and tempered components, the annealing temperature should be selected 30…50 K below the tempering temperature in order not to reduce the hardness.
Do you want more information about induction heating and the available options? Contact Smit Heat Treatment and one of our specialists will be happy to help you.
Do you want more information about induction heating and the available options? Contact Smit Heat Treatment and one of our specialists will be happy to help you.