Failure analysis of the carburized 20MnCr5 gear in fatigue working condition

This paper analyzed the reason of the fatigue failure of the carburized 20MnCr5 gear and proposed optimized carburizing process. The number of load cycles of the failure carburized gear was 2.4 million times. The carburized layer was 0.52 mm and dissatisfied the requirements. The number of load cycles of the carburized gear with optimized carburizing process was 8.4 million times. The depth of the carburized layer was 0.75 mm. The shallow depth of carburized layer, low hardness and less retained austenite in the microstructure caused by insufficient carburization were main reasons of the low fatigue life of the failure carburized gear.