Generally modelling of material behavior and surface modifications for FEM analysis of die forging of carbon steels

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For the thermomechanical simulation, the main focus should be on the real oxide scale kinetic, because this has an influence on the processes in the forming zone. During the first funding period, the modelling of the oxide scale layer during forming was carried out without a damage criterion. However, in real forming processes critical stresses cause cracks or sliding in the scale layer. For a detailed representation of the local material temperature and friction conditions, which significantly influence the forming process, the damage behaviour of the oxide scale during forming must be considered in the numerical simulation. To achieve a comprehensive view of the process chain, the formation of oxide in the heating unit must already be considered numerically and as input data for the following hot forming simulation. The changes of the material properties of the base material as well as the oxide scale layer have to be implemented into the commercial FE-program Simufact.Forming by using Fortran-subroutines. Therefore, an input for the coupled process chain simulation in hot forging can be realised, taking into account the oxide scale formation as well as the oxide damage behaviour, the microstructure evolution and the tribological system as a function of the relevant parameters and alloying elements.