PSI - Issue 51

Milan Uhríčik et al. / Procedia Structural Integrity 51 (2023) 166 – 172 M. Uhrí č ik et al. / Structural Integrity Procedia 00 (2022) 000–000

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shows a smaller number of cycles to fracture than austenitic steels in the initial state. This is due to the fact that samples for austenitic steels after plasma nitriding were loaded with a higher load.

Fig. 3. Results of fatigue tests for austenitic steel AISI 304 in the initial state and after plasma nitriding.

The number of cycles that samples endured to fracture at a given load, was 4.56x10 5 cycles for austenitic steel in the initial state and 8.25x10 4 cycles for austenitic steel after plasma nitriding, both tests performed at room temperature. Macrostructures of austenitic steels after the fatigue test for both states are shown in Fig. 4, on which it is possible to recognize individual areas (fatigue area, transition area and static failure area) on fracture surfaces of samples.

a b Fig. 4. Macrofractures of austenitic steels AISI 304 after the fatigue test; (a) in the initial state; (b) after plasma nitriding.