Residual stress oriented joining of hybrid components by radial-rolling

Flexible manufacturing processes in forming technology make a quick and efficient response to changing conditions, for example due to customer demands and legal requirements, possible. The incremental forming processes in the area of bulk metal forming in particular are characterized by a high degree of flexibility, as the processes are readily adaptable and the equipment and tools used are less component specific. The joining process presented here by means of radial rolling is suitable for joining hybrid components by a combined form-fit and force-fit. In this way, the specific advantages of different materials can be combined and application as well as lightweight potentials can be taken advantage of in a targeted manner. The characteristic circumferential notch in the shaft component created in this process forms a weak point in the joined components, as stress concentrations occur in the notch ground under load. This increases the risk of crack formation in this area. This challenge is met by a combination of exploiting the work hardening of the selected material (1.7225) and selectively inducing residual compressive stresses in the notch. The focus here is on the residual compressive stresses, which have the potential to extend the component's fatigue life. They can be specifically influenced by an advantageous choice of the rolling path for producing the joint, as shown both in numerical analyses and by residual stress measurements on real components. Very high residual stresses can be introduced in the critical zone of the notch ground, which have a significant influence on the service life, as is also evident in the fatigue life simulations using the local concept.

Automated summary

Flexible manufacturing processes in forming technology allows quick and efficient adaptation to changing conditions, such as customer demands and legal requirements. In particular, the incremental forming processes in bulk metal forming show high flexibility and adaptability. The joining process presented focuses on combining the advantages of different materials and exploiting their lightweight potentials by introducing specific residual compressive stresses in the joint area to extend the component's fatigue life.