PSI - Issue 18

Kim Bergner et al. / Procedia Structural Integrity 18 (2019) 792–801 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The FKM-guideline was composed of a large database, but does not take into account the influence of casting skin on fatigue strength in its entirety, meaning a deviating microstructure beneath the surface. This deviation between guideline and experimental results motivated the investigation of various casting skin conditions and bulk material combinations. 5. Conclusion and Outlook The results presented in this paper show an accurate and reliable fatigue assessment concept, which considers casting skin as more than surface roughness, but as a combination of graphite degenerations and microstructural changes in addition to surface roughness. Therefore, it is important not only to investigate the cyclic fatigue properties of the bulk material of casting components, but also the whole layer system, consisting of surface roughness, graphite degenerations and deviating microstructures. Further work in this research project also contains investigations on EN-GJS-700-2 and the influence of shot peening on the fatigue strength of casting skin-containing specimens. In addition to this, FE-simulations are carried out to develop a fatigue assessment concept, based on the test results gained from the cyclic fatigue tests and the cyclic material properties determined by strain-controlled fatigue tests on small scale flat specimens under axial, alternating loading. All information will be included in an assessment concept to assess the local fatigue strength of nodular cast iron components with rim zones. To validate the correctness of this fatigue assessment concept, a cast iron component made of nodular cast iron will be simulated and fatigue tested at the end of the project. 6. Acknowledgements The results presented in this paper were derived during the research project “Gusshaut”. For the funding of this project, sincere thanks are given to the German Federation of Industrial Research Association (AiF). Furthermore, all project partners are thanked for their participation and support to complete this project successfully. 7. References Bauer, W., 1982, Untersuchungen über die Störung der Kugelgraphitausbildung in der Randzone von Gusseisen mit Kugelgraphit beim Gießen in mit para-Toluolsulfonsäure gehärtete Formsandformen, Gießerei-Praxis, Vol. 11, p 175-183 Bleicher, C.,2016. Ein Beitrag zur Beurteilung der Schwingfestigkeit von Gusseisen mit Kugelgraphit mit besonderer Berücksichtigung der Auswirkungen von Lunkern auf die Bauteillebensdauer, Fraunhofer Institute LBF, LBF report no. FB-246 FKM-Richtlinie, 2012, Rechnerischer Festigkeitsnachweis für Maschinenbauteile, 1. Ausgabe, Forschungskuratorium Maschinenbau (FKM), Frankfurt am Main Kaufmann, H., 1998. Zur schwingfesten Bemessung dickwandiger Bauteile aus GGG-40 unter Berücksichtigung gießtechnisch bedingter Gefügeungänzen, Fraunhofer Institute LBF, LBF report no. FB-214 Kutz, A., 2018: Microstructural Adjustment of the Degenerated Graphite Layer in Ductile Iron for Targeted Evaluation and the Fatigue Properties, Keith Millis Symposium on Ductile Cast Iron Rausch, T., 2011, Zum Schwingfestigkeitsverhalten von Gusseisenwerkstoffen unter einachsiger und mehrachsiger Beanspruchung am Beispiel von EN-GJV-450, Shaker Verlag, Aachen Schönborn, S., 2011, Zur Bemessung von zyklisch innendruckbeanspruchten Bauteilen aus Gusseisenwerkstoffen mit Kerbgrundkonzepten, Fraunhofer Institute LBF, LBF report no. FB-248 Sonsino, C. M., 2005, Dauerfestigkeit – Eine Fiktion, Konstruktion 57, Issue 4, p. 87-93 Spindel, J., 1979, The method of maximum likelihoof applied tot he statistical analysis of fatigue data including run-outs, S.E.E. International Conference, University of Warwick, Conventry, p. 7.1-7.23