某冲击器砧子断裂失效分析

Failure Analysis on the Rupture of a Hammer Anvil

某液动冲击器在井下应用过程中,其砧子上端面出现断裂。采用宏观形貌分析、化学成分测试、表面硬度检测、电镜扫描、力学性能试验以及金相组织分析等方法对其断裂原因进行了分析。结果表明,砧子材料碳含量低于40CrMnMo规范要求的下限,且存在较明显的偏析和团聚状分布的非金属夹杂物,一定程度上影响了砧子材料的综合机械性能。砧子裂纹属于机械疲劳裂纹,起源于内孔端面附近的应力集中位置,材料强度偏低和局部工作应力偏高是导致疲劳开裂的主要原因。

A rupture was found on the upper surface of a hydraulic hammer anvil after down-hole services. The reason was investigated by means of macro-morphology analysis, chemical composition analysis, surface hardness test, SEM observation and mechanical tests. Results show that in the anvil material the carbon content is even lower than the lowest limit of 40CrMnMo specification, with obvious segregation and reunion shape distribution of non-metallic inclusion, which supposedly affects its comprehensive mechanical properties. The anvil crack belongs to mechanical fatigue crack, originating from the inner hole near the end of the stress concentration point.