采用宏观观察、金相检验、扫描电镜分析、硬度测试等方法对某衬筒零件断裂原因进行分析。结果表明：衬筒端头经过局部淬火处理后，其显微组织变为异常粗大的马氏体，硬度增大且脆性增加；在使用过程中衬筒受到摩擦和挤压的作用，当压力达到一定程度时，衬筒发生脆性断裂。

The causes of a liner parts fracture were analyzed by means of macroscopic observation, metallographic examination, scanning electron microscope analysis and hardness test. The results show that after local quenching treatment, the microstructure of the liner end became abnormal coarse martensite, the hardness increased and the brittleness increased. The liner was subjected to friction and extrusion during use, and brittle fracture occured when the pressure reached a certain degree.