某四缸汽油机曲轴断裂失效分析

Failure Analysis of Crankshaft Fracture for some Four-Cylinder Gasoline Engine

针对一起性能试验中的汽油机曲轴断裂问题,对断口进行了宏观分析、微观分析、金相组织检验、力学性能检测等,对曲轴的断裂原因进行了分析。结果表明:该曲轴断裂失效是典型的疲劳失效,主要原因是第四连杆轴颈圆角滚压与沉割槽过渡处有接痕,产生应力集中导致的疲劳断裂,提高圆角滚压质量是解决该曲轴失效的根本途径。

As for the crankshaft fracture in the gasoline engine performance test,the causes are analyzed with macro analysis,micro analysis,metallographic structure test,mechanical property test,etc..It is indicated that the crankshaft fracture is typical fatigue failure,and this is mainly caused by stress concentration generated by the lapping defect between the fillet rolling and undercut gap of the fourth connecting rod journal.Therefore,improving the fillet rolling is the basic solution for this crankshaft failure.