高压燃油泵溢油阀断裂失效分析

Failure Analysis on Fracture of Spill Valve of High Pressure Fuel Pump

某高压燃油泵溢油阀在服役过程中发生断裂,通过尺寸设计与原材料选用分析、化学成分分析、断口分析、金相分析、有效硬化层深度测试、硬度测试、镀锌层厚度测试、孔径尺寸测试等方法对溢油阀断裂原因进行了分析。结果表明:该溢油阀失效模式属于氢脆延迟断裂。溢油阀表面渗碳淬火处理导致其硬度偏高,氢脆敏感性增强;酸洗镀锌过程中由于未进行脱氢处理,导致溢油阀表面发生氢聚集,最终在安装应力和氢的共同作用下发生氢脆断裂。最后针对溢油阀断裂原因提出了预防措施。

The spill valve of a high pressure fuel pump fractured during its service.The fracture causes of the spill valve were analyzed by means of dimension design and raw material selection analysis,chemical composition analysis,fracture analysis,metallographic analysis,effective hardening layer depth test,hardness test,galvanized layer thickness test and hole size test.The results show that the failure mode of the spill valve belonged to the delayed hydrogen embrittlement fracture.The carburizing and quenching treatment on the surface of the spill valve resulted in higher hardness and higher hydrogen embrittlement sensitivity.Hydrogen aggregation occurred on the surface of spill valve due to no dehydrogenation treatment during pickling and galvanizing,and hydrogen embrittlement fracture occurred under the combined action of installation stress and hydrogen.Finally,preventive measures were put forward for the fracture causes of the spill valve.