PSI - Issue 51

Alan Vaško et al. / Procedia Structural Integrity 51 (2023) 129–134 A.Vaško et al. / Structural Integrity Procedia 00 (2022) 000–000

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 fatigue tests according to STN 42 0362 under low-frequency sinusoidal cyclic push-pull load (stress ratio R = –1) at frequency f  75 Hz at room temperature (T = 20  5 °C) on 15 test specimens of circular cross-section with a diameter d 0 = 8 mm (Fig. 1).

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Fig. 1. Experimental machine and test specimen used for fatigue tests; (a) fatigue testing machine Zwick/Roell Amsler 150HFP 5100; (b) shape and dimensions of the test specimen. 3. Experimental results and discussion The microstructure of the specimen of EN-GJSA-XNiCr20-2 nodular cast iron is shown in Fig. 2a. The microstructure is formed by a homogeneous austenitic matrix in which graphite is excluded in the form of nodules. In addition, there are chromium carbides, which are regularly distributed in the austenitic matrix. A detail of nodular graphite and carbide in the basic metal matrix is shown in Fig. 2b.

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Fig. 2. Microstructure of austenitic nodular cast iron EN-GJSA-XNiCr20-2, etched by Marble.