PSI - Issue 25

Pedro R. da Costa et al. / Procedia Structural Integrity 25 (2020) 445–453 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Figure 4. Tension/torsion specimen for VHCF

A metallurgical analysis of the material was priory made since research’s related to fatigue frequency affects in relations to the material’s microstructure (Bach, Göken, and Höppel 2018; Dönges, Fritzen, and Christ 2018; Grigorescu et al. 2018; Hilgendorff et al. 2018) has proven to have a direct influence on the results. 3. Results Experimental fatigue tests were carried out on the ultrasonic fatigue testing machine for the cylindrical three throat tension/torsion specimens shown in figure 4. A metallurgical analysis of the railway wheel’s metal in the rim and in the web region was made as aforementioned, and is presented in figure 5.

Figure 5: (A) Prepared samples for microstructural analysis; (B) Web region: Optical 500x zoom; (C) SEM (10000x); (D) Rim region: Optical 500x zoom ;(E) MEV (10000x).

In Figure 5 the microstructure images of the Web ((B) and (C)) and the Rim ((D) and (E)), show a perlite ferrite microstructure with a predominant perlite phase. The microstructure analyses show, for the same low magnification (Fig. 10 (B) and (C)), differences in the microstructure distribution and grain size. In the Rim section a smaller grain and more disorder arrangement of the perlite phase is found, related to a higher cooling rate treatment.