Failure Analysis of Special-shaped Rail Cracking

The longitudinal cracks appear in the rail waist of U75V special-shaped rail during secondary heat processing.The common rail, one-time formed special shaped rail and thermal-corrected (secondary heat processing)special shaped rail were sampled respectively, and the material composition examination, mechanical properties test and metallographic structure observation were carried out. The fracture surface was analyzed by SEM and EDS. The results show that the grain size of two-time hot processing rail is coarse and there is over-burning phenomenon, the surface layer is decarbonized, and the mesh structure is formed.Due to the local heating in the secondary heating correction, the restraint stress of the heating area during cooling is large, which leads to the longitudinal hot crack in the cooling process.