电力机车均衡梁断裂原因

Cause of Fracture on Equalizing Beam of Electric Locomotive

某电力机车均衡梁在安装过程中发生断裂,通过化学成分分析、力学性能测试、金相检验、扫描电镜分析等方法对该均衡梁的断裂原因进行了分析。结果表明:电力机车均衡梁的铝含量过多,在晶界处形成了氮化铝薄膜,使晶界的强度大幅度降低,且该现象通过热处理很难消除;组织中存在缩孔、夹渣等铸造缺陷,在装配过程中缺陷处容易产生应力集中,降低了该配件能够承受的载荷,最终导致均衡梁发生了脆性断裂。

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.