Cyclic deformation behaviour of railway wheel steels in the very high cycle fatigue (VHCF) regime

In the present contribution, the cyclic deformation behaviour of the railway wheel steels SAE 1050 and SAE 1060 was investigated in the very high cycle fatigue (VHCF) regime using a resonance testing device at a frequency of 200 Hz. The specimens were machined from the area of the ‘limiting-diameter’ of original monobloc-wheels. The wheels were provided by a system supplier of the Deutsche Bahn AG. The cyclic deformation behaviour is analysed by using highly precise methods for measuring the frequency, temperature and electrical resistance, which show deformation-induced changes of the microstructure within the bulk material during the fatigue process. The initial state of the material is investigated thoroughly by using light-, scanning- and transmission electron microscopy. The dislocation structure was investigated in defined fatigue states showing dislocation walls at 5% Nf and dislocation cells at 85% Nf. S–N (Woehler) curves are presented for both wheel steels. Fatigue failures at Nf > 107 were observed.