The aim of this project is to predict and increase the fatigue life cycle of upset formed joints. From the literature, it is known that initial cracks occur at the inner bending radius. Therein, shearing and elastic springback are claimed as the reasons for the cracks and are therefore investigated in the following. SEM analysis revealed that for different strain states shear fractures occur at the inner bending radius, confirming shearing as the cause of cracks. The influence of the elastic springback on the crack initiation is investigated with bending experiments in DP600, Al99.5, and 1.4301 (see Figure). To prevent elastic springback, the specimens are secured with screws post-bending which are then removed. Microscopic analysis of the secured bent samples revealed initial cracks in the materials, which proves shearing as the rootcause. Comparing the same initial crack in fastened and unfastened condition showed an increased crack length after fastener removal. Future analysis will focus on the influence of the microstructure on the fatigue life.