This paper presents the results of the failure analysis of high-pressure fuel injection lines of a diesel engine that caused fire on the public transportation bus. Fuel injection lines had been in operation for 18 months, and two of them were cracked at the point where they were connected to the engine injector. These damages caused fuel leaks and finally fire on the bus which spread into the passenger cabin and caused significant damage. The failure mechanism was analysed by both visual and SEM inspection of the fracture surface, identifying fatigue as the major cause of the final failure. Microstructure analyses, microhardness measurements together with chemical analysis were performed in order to check any possible deviation in the material structure and/or composition. The results showed that fatigue failure occurred due to the decarburization of the outer surface of the high-pressure lines.

本文介绍了导致公共交通巴士着火的柴油机高压燃油喷射管路的故障分析结果。燃油喷射管线已经运行了18个月，其中两条在与发动机喷射器连接的位置破裂。这些损坏导致燃油泄漏，并最终在公共汽车上起火，并蔓延到乘客舱内并造成重大损失。通过目测和SEM检查断裂表面来分析失效机理，确定疲劳是最终失效的主要原因。进行微观结构分析，显微硬度测量以及化学分析，以检查材料结构和/或成分的任何可能偏差。