铰链梁在使用过程中铰耳发生断裂，采用宏观分析、化学成分分析、力学性能测试、金相检验、断口扫描电镜分析等方法，对铰耳断裂原因进行了分析。结果表明：铰链梁中的残余铝含量和氮含量较高，夏季铸造时冷速过慢，使得一次奥氏体晶界析出AlN夹杂物造成晶界脆化，同时晶界上大量的铸态MnS以及Al₂O₃类夹杂物也加剧了晶界的脆化，导致铰链梁铰耳在使用过程中发生沿晶脆性断裂。

Hinge beam ears were fractured in the process of use. The fracture reasons for the hinge beam ears were analyzed by macroscopic analysis, chemical composition analysis, mechanical property test, metallographic examination and fracture SEM analysis. The results show that the residual aluminmm content and nitrogen content in the hinge beam were high, and the cooling rate was too slow in the summer, which made the grain boundary embrittlement due to the precipitation of AlN inclusions on the austenite grain boundary. At the same time, a large number of as-cast MnS and Al₂O₃ inclusions on grain boundary also aggravate the grain boundary embrittlement, and the intergranular brittle fracture of the hinge beam occurred in the process of use.