Influence of the Multiaxial Bauschinger Effect in Cold Forging

Funding: German Research Foundation (DFG)
Project: 418815343
Contact: Felix Kolpak M. Sc.

In the DFG-funded project new methods were developed that allow the characterization of anisotropic hardening effects exhibited at large strains (see figure).

By using and modifying the kinematic work hardening model according to Yoshida and Uemori (2002), all anisotropic hardening effects exhibited by the case-hardening steel 16MnCrS5 could be captured with high accuracy over the entire relevant strain range. By using the model, the prediction quality of component properties (hardening and residual stresses) could be improved significantly by means of FEM simulation of forward rod extrusion. In the area of cold bulk forming, multi-stage or combined forming processes are frequently used to produce complex, highly stressed parts. Thus, certain material regions are sometimes formed multiple times. If a load reversal occurs locally, this can trigger anisotropic hardening phenomena. It is expected that the use of the model in multi-stage process chains will also reveal an influence on process forces and tool loads.

Characterization and modeling of anisotropic hardening at large strains