某柴油机高压油管在使用过程中发生开裂，对开裂油管进行了宏观分析、化学成分分析、金相检验以及断口分析，确定了油管的开裂原因。结果表明：该油管开裂主要是因为其内壁存在裂纹、毛刺等加工缺陷，在工作过程中的交变应力作用下裂纹以疲劳方式扩展并造成开裂；油管未进行调质处理以及振幅偏大，促进了疲劳裂纹的扩展。最后对高压油管提出了改进建议。

The high pressure fuel pipe of a diesel engine cracked during use. The cracking reasons of the fuel pipe were analyzed by means of macro analysis, chemical composition analysis, metallographic examination and fracture analysis. The results show that the cracking of the fuel pipe was mainly due to the inner wall processing defects such as cracks and burrs. The cracks continued to propagate in fatigue mode under the action of working alternating stress and finally resulted in cracking. At the same time, the non-quenched and tempered microstructure and large amplitude promoted the fatigue crack propagation. Finally, improvement suggestions to the high pressure fuel pipe were proposed.