Cause of Fracture on Equalizing Beam of Electric Locomotive

The equalizing beam of an electric locomotive fractured during installation. The fracture causes of the equalizing beam were analyzed by means of chemical composition analysis, mechanical property test, metallographic examination and scanning electron microscope analysis. The results show that the aluminum content in the equalizing beam of electric locomotive was too much, and the aluminum nitride film was formed at the grain boundary, which greatly reduced the strength of the grain boundary, and this phenomenon was difficult to be eliminated by heat treatment. There were casting defects such as shrinkage cavity and slag inclusion in the structure. The stress concentration was easy to occur in the defects during the assembly process, which reduced the load that the accessory could bear, and finally led to the brittle fracture of the equalizing beam.