Analysis of the Reasons for the Spalling Defects on U71Mn Rail Treads

Served as the high rail on railway curve,different degrees of spalling defects appeared on U71Mn rail tread after a period of time.The performance testing of rail with defects indicated that the chemical composition,hydrogen-oxygen content,tensile properties,decarburized layer,metallurgical structure,non-metallic inclusions and surface hardness and so on all satisfied the requirements of TB/T2344-2012 standard.Therefore,the generation of spalling defects had no direct relation with rail quality itself.The analysis of the defect characteristics indicated that the spalling defects found on rail running surface were a sort of typical rolling contact fatigue damage,which was mainly caused by the excessive contact stress,as a result of the wheel long-term contact with rail on the gauge corner of the high rail on curve.It is effective to prevent and reduce the spalling defects by the following measures,such as improving the wheel-rail matching relationship to form conformal contact,reasonable preventive grinding and corrective grinding for rails,and strict executing the regulations for rail application by classification.