The influence of the bake hardening effect on thermal and cyclical decay of residual stresses induced by shot peening

The interaction between interstitial atoms such as nitrogen or carbon and dislocations in steels are well known under term Cottrell atmospheres. The influence on mechanical properties of mild steels is also well known and has been observed repeatedly. Furthermore, mechanical behavior under cyclic loading is also affected by these interactions. The multitude of possible parameters such as material properties or chemical composition as well as their interdependences require that the effects be considered separately. This work examines the influence of these interactions on thermal and cyclical decay of residual stresses. The investigations were performed on the bake hardening steel ZSTE 220 BH, because this material can be expected to exhibit particularly pronounced strain hardening effects and is therefore ideally suited for this work.