The objective of the project “Simulation based determination of the failure potential of silicon alloyed spherical graphite cast irons subject to fatigue loading” is to provide designers with the fatigue parameters that serve as a basis for assessing silicon alloyed cast iron materials. For this purpose, two materials: GJS 500-14 and GJS 600-10, are tested subjected to both axial as well as torsional loading for varying stress ratios and notch factors. Besides the graphite’s spherical characteristics (forms VI and V), the influence of the graphite’s properties on the cyclic mechanical properties will also be investigated. For this purpose, specific material states are established and tested which possess reduced roundness of the graphite particles as well as chunky-graphite that leads to a severe reduction in the static properties of components having large wall thicknesses. Using the correlation of the microstructural parameters: such as size, form and distribution of the graphite particles, with the fatigue strengths, a catalogue of boundary samples will be compiled for the graphite’s properties. Moreover, metallographic image analyses serve as the basis for developing a model with which the cyclic mechanical properties of real microstructures can be simulated using representative volume elements.