Fracture Analysis of U75V Welding Rail during Installing Process

A 500 m welding rail fractured transversely at the middle position during installing process.Macro examination,chemical compositions analysis,fracture analysis,microstructure examination were introduced to study the fracture reason of the rail.The results indicate that metallurgical quality of the rail was good and it was the martensite microstructure at the rail tread surface that resulted in the fracture under the action of bending pulling stress.The rail was ground to make sure its straightness and then the martensite structure was formed at the rail tread surface because of the local high temperature caused by the improper grinding.