In cold-formed components, locally different residual stresses develop over the entire component volume. A precise knowledge of the distribution and the amount of the production-induced residual stresses is of particular importance in the design of cyclically loaded components. This relates in particular to materials in which the strength is not adjusted by a heat treatment, but exclusively by the strengthening mechanisms resulting from cold forming.
While a certain level of basic knowledge of residual stress formation is existing in simple cold-forging processes, there is still a considerable need for research in terms of the stress distribution as a function of the individual process steps in multi-stage process manufactured components. Moreover, the effects of different residual stresses on the performance of complex stressed components are not yet fully understood.
As an example of improvement of performances through the adjustment of residual stresses, the process chain of austenitic steels is taken into account within the framework of the project. An analysis of the single steps of production is performed. Parallel to the experimental investigation, the optimization of existing numerical models for the residual stress distribution is carried out as a function of different process parameters during cold forming. The aim is to be able to make a quantitative statement regarding the residual stress state with the help of the numerical simulation. Finally, the reproduction of residual stresses, which can be achieved across the entire process chain, is analyzed. From the knowledge and the understanding of the mechanisms, measures are taken to improve the properties of the workpieces.
The Institute for Production Engineering and Forming Machines would like to thank the German Research Foundation (DFG) for the support in this project.