Zbornik radova Koridor 10 - Kirilo Savić

3rd International Scientific and Professional Conference
CORRIDOR 10 - a sustainable way of integrations
initial crack, until the rail breaks under the influence of variable traffic load, which is transferred to the
rail via a small wheel/rail contact surface.
Generally, a fracture surface due to rolling contact fatigue has a characteristic figure. Two visually
different surfaces can be distinguished: fatigue area and rail break area (Figure 2).
FIGURE 2. Characteristic look of a steel surface after break caused by rolling contact fatigue
Rolling contact fatigue cracks on the rail can be classified into those that are subsurface-initiated and
surface-initiated. Subsurface-initiated cracks are normally a consequence of high vertical loading in
combination with material imperfections. The subsurface-initiated cracks occurred more frequently in
the past. The development of steel making technology has reduced rolling contact fatigue defects
associated with material imperfections (Figure 3).
FIGURE 3. Example of cracked oxide/silicate inclusion which can act as an
initiation site for shelling and transverse defects [5]
On the other hand, most surface initiated cracks are the result of wheel/rail interaction (Figure 4) and a
high load transfer over the small wheel/rail contact patch (Figure 5). The contact patch is elliptical in
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