13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- 4. Conclusions The high strength steel 34CrNiMo6 was investigated in the very high cycle fatigue regime under constant and variable amplitude loadings. An ultrasonic fatigue testing system has been used to perform fatigue tests in adequate testing time. An own developed software UFaTeSVAL was used to realize variable amplitude loading tests. Two-step load amplitudes and reconstructed load time histories were investigated. The main conclusions are as follows: (1) The fatigue life of variable amplitude tests is influenced by the size of non-metallic inclusions, in contrast to constant amplitude loadings. (2) The two-step loading tests show that load amplitudes below the fatigue strength can contribute to damage depending on the height of the maximum load amplitude and the amount of maximum load amplitudes. (3) Variable amplitude loading can provoke the occurrence of arrest marks around non-metallic inclusions within fish-eyes, which are used to calculate a mean fatigue crack growth rate in the fish-eye. (4) As the FELIX investigations show, an influence of the kind of reconstruction of the load-time is observable. Acknowledgements The authors gratefully acknowledge the financial support by the ‘Deutsche Forschungsgemeinschaft’ (DFG) in the framework of SPP 1466. References [1] Bathia s, C.: There is no infinite fatigue life in metallic materials. In: Fatigue Fract Engng Mat Struct 1999; 22(7): pp. 559-65 [2] Marin es, I.; Dominguez, G.; Baudry, G.; Vittori, J.F.; Rathery, pp.; Doucet, J.P. et al.: Ultrasonic fatigue tests on bearing steel AISI-SAE 52100 at frequency of 20 and 30 kHz. In: Int. J. Fatigue 2003; 25: pp. 1037-1046. [3] Pyttel, B.; Schwerdt, D.; Berger, C.: Very high cycle fatigue - Is there a fatigue limit? In: Int. J. Fatigue 2011; 33: pp. 49-58 [4] Sakai, T.: Review and prospects for current studies on very high cycle fatigue of metallic materials for machine structural use. In: J. Solid Mech Mater Eng 2009; 3(3): pp. 425-439. [5] Shioza wa, K.; Lu, L.; Ishihara, S.: S-N curve characteristics and subsurface crack initiation behavior in ultra-long life fatigue of a high carbon-chromium bearing steel. Fatigue Fract Engng Mat Struct 2001; 24(12): pp. 781-90 [6] Tanak a, K.; Akinawa, Y.: Fatigue crack propagation behavior derived from S-N data in very high cycle regime. Fatigue Fract Engng Mat Struct 2002; 25: pp. 775-84 [7] Ochi, Y.; Matsumura, T.; Masaki, K.; Yoshida, S.: High-cycle rotating bending fatigue properties in
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