Development of a test methodology to determine the re-hardening and tempering effects of forging tools under cyclic thermomechanical loading to improve numerical wear prediction

The innovative contribution of this research project consists in particular in the development of a test methodology for determining the hardness and microstructure development of hot-work steels as a function of the forging cycles and the resulting thermal and mechanical load. It must be taken into account that, depending on the load in combination with high cooling rates due to spray cooling, localised rehardening of the microstructure can also occur.

Based on the determined hardness curves, the Archard model is extended to take into account the local hardness development as a function of the number of cycles and thermal as well as mechanical loads. By taking into account local rehardening and tempering effects in the wear calculation of commercial FE systems, a better understanding of the evaluation of tool stress and the prediction of tool life is enabled. In this way, tool life can be increased and production losses reduced by adapting the process and tool design.