Zbornik radova Koridor 10 - Kirilo Savić

3rd International Scientific and Professional Conference
CORRIDOR 10 - a sustainable way of integrations
FIGURE 12. Influence of traction on the contact shear stress [5]
(Note: T/N is the traction coefficient or the ratio of tangential to normal forces)
Figure 13 shows that the work hardened layer can be up to 8-10 mm in depth from the rail contact
surface. The plastically deformed steel in the work hardened layer exhibits high compressive residual
stresses. Such stresses inhibit fatigue crack growth, and prevent the growth of the much shallower
checking cracks (up to 8-10 mm) into the rail head. On the contrary, the deeper shelling cracks may be
able to penetrate through the compressive work hardened layer and continue growing on a transverse
plane. The shelling cracks can being developed into transverse defects by the action of other stress
environments, including rail bending, thermal stresses, and residual stresses due to rail manufacture.
FIGURE 13. Hardness distributions in standard carbon rails
in tangent track at 30 to 35 tones axle loads [5]
Also, it is possible that the checking cracks may be able to advance into the rail head. This
phenomenon occasionally leads to the unexpected rail failures under lower axle load, high speed
passenger track, since such conditions would lead to a very limited (if any) work hardened
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