Cracking Reason Analysis and Improvement Suggestions on a High Pressure Fuel Pipe

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.