Crack failure analysis of 1Cr18Ni9Ti stainless steel fuel supply pipeline
During the reliability test of a certain type of engine,one of the fuel supply pipelines made of 1Cr18Ni9Ti experi-enced fuel leakage.After X-ray inspection,it was found that there was a crack at the flaring R angle of the fuel supply pipe-line.Through appearance inspection,metallographic inspection,fracture analysis and chemical composition detection of the crack of the pipeline,the properties and causes of the R angle crack were determined.The experimental results showed that the nature of the crack was fatigue crack,which originated from the outer surface of the part and exhibited point source char-acteristics.The initial stress and propagation stress of the fatigue crack were relatively small.The main reason for the genera-tion of the fatigue crack was related to the abnormal vibration caused by loose nuts during engine testing and the presence of grinding marks in the source area.It is recommended that similar pipeline parts no longer be polished with grinding wheels.Instead,clamps should be installed to support and secure the fuel supply pipeline to prevent the loosening of the nuts and the occurrence of abnormal vibration.
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