PSI - Issue 79

Christoph Bleicher et al. / Procedia Structural Integrity 79 (2026) 239–247

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Fig. 6. Influence of test frequency under sea water for R σ = -1.

5. Summary and Outlook During the investigations, the cyclic material behavior of Cu3 bronze alloys for usage in corrosive media were investigated. As result, the S-N curves with their different slopes and knee points as well as the resulting mean stress sensitivities in air and seawater were determined and compared to literature results. It was determined that the cyclic material behavior in terms of slope and the position of the knee point differ strongly, both, in relation to the load ratio and in relation to the surrounding media. While the mean stress sensitivity for the material stayed constant under ambient air and artificial sea water, the achieved nominal stress amplitude is reduced. An influence of the test frequency on the fatigue strength could not be determined neither when reducing the fre quency to 5 Hz nor by increasing it to 45 Hz. Unfortunately, it was not possible to define an upper limit of the fre quency until no influence on the material’s lifetime is detectable. In further steps, more investigations around the fatigue strength of Cu3 alloys will be conducted regarding the influence of different manufacturing parameters like the wall thickness or molding material humidity. Moreover, de tailed metallographic investigations are conducted to derive significances in the microstructures between different casting geometries and wall thicknesses. Acknowledgements The results presented in this paper were derived during the research project „Bross“. For the funding of this project, sincere thanks are given to the German Federal Ministry for Economic Affairs and Climate Action (BMWE). References ASTM 2013. D1141-98 - Standard Practice for Preparation of Substitute Ocean Water. ASTM International, DOI: 10.1520/D1141-98R21 Bertolgio, C., Rizzo, C., 2016. Survey on fatigue strength of cast bronzes intended for marine propellers. Fatigue and Fracture of Engineering Materials and Structures, 39 (7), pp. 793 - 816, DOI: 10.1111/ffe.12440. Bleicher, C., Wagener, R., Kaufmann, H., Melz, T., 2015. Fatigue strength of nodular cast iron with regard to heavy-wall application. Materials Testing, Carl Hanser Verlag, no. 9, pp. 723 – 731, DOI:10.3139/120.110782. Bleicher, C., Wagener, R., Kaufmann, H. Melz, T., 2017. Fatigue Assessment of Nodular Cast Iron with Material Imperfections. SAE International Journal of Engines, 10 (2), pp. 340-349, DOI: 10.4271/2017-01-0344. Chakrabarti, A., Sarkar, A., Saravanan, T., Nagesha, A., Sandhya, R., Jayakumar, T., 2014. Influence of Mean Stress and Defect Distribution on the High Cycle Fatigue Behaviour of Cast Ni-Al Bronze. Procedia Engineering, vol. 86, pp. 103 - 110, DOI: 10.1016/j.proeng.2014.11.017.