Determination of fatigue lives and origin of crack initiation of steel piston alloys in the VHCF regime at elevated temperatures (T02*)

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Based on the knowledge gained in the subproject C04 during the first funding period of the CRC 920, the aim of the present proposal is to evaluate the fatigue properties of steel piston alloys in the application relevant temperature range between 200°C and 500°C up to 109 number of cycles. The investigations are focussed on the influence of materials production conditions (cast andwrought alloys), the chemical composition, the microstructure and defects like (pores, micro shrinkage cavities, non-metallic inclusions). Especially, investigations on the damage relevant defect size as well as damage accumulation are of great interest. The expected results can contribute to the clarification of occurring damage mechanisms in steel piston alloys at elevated temperatures and give finally a contribution to a modified design of piston geometries. Furthermore, results on the formation of damage relevant inclusion agglomerates can improve the entrapment capability of metal melt filters developed in the framework of the CRC 920 bymodification of the coating on the surface of filter struts.