Fracture Reason Analysis for Rail on Line

The U75V hot-rolled rails laid on the curving line had been used more than three years,one of them had fractured,and some other had fatigue damage of desquamation.The physical and chemical inspection was carried out to find the fracture reason.The results indicated that the contact stress of rail and wheel was too excessive and exceeded the yield strength of rail.Because the fatigue crack expansion rate exceeded the wearing speed rate,the fatigue crack generated on the surface of the rail's plastic deformation field,and the crack extended along the deformation streamline,then the nucleus of crack caused in the round under the contact surface of rail and wheel about 2 mm.Finally,the rail had fractured in the wheel rolled repeatedly.