Causes Analysis on Damage of U75V Hot-rolled Steel Rails

Parts of U75Vhot-rolled steel rails which were laid in the line with the curve radius R=400m appeared contact fatigue cracking and peeling after two years,and the damage reasons were analyzed by means of chemical compositions analysis,scanning electron microscope and energy dispersive spectrometer analysis and metallographic examination.The results indicate that the main reason for the contact fatigue cracking and peeling damage was that the contact stress of the contact round corner of the rail and wheel was too large and exceeded its fatigue strength,which resulted the fatigue cracks initiated in the rail's plastic deformation layer and propagated along the deforming line,and finally caused crosswise fatigue damage on the contact round corner of rail and wheel.Measures such as improving the metallurgical quality,laying high strength rails,improving the contacting condition of the rail and wheel to change the stress state and polishing the rails with contact fatigue cracks could be adopted to extend the service life of the rails.