Fracture Reason of Castellated Shaft in Electric Generator of an Aircraft

The castellated shaft of 50CrVA located in an aircraft engine was broken.The macro appearance and the microstructure of castellated shaft fracture observed by optical microscopy and scanning electron microscopy.The fracture elements were analyzed by EDS.The results showed that the spline shaft worked under torsional stress and at high work temperature,Cd in the plating permeated to the matrix grain boundaries,resulting in brittle fracture caused by the decrease of intergranular binding force.The aircraft generator working environment factors determined that the cadmium plating process of the spline shaft was unreasonable and easily caused intergranular brittle fracture of artifacts.The plating process should be changed and all the parts should be replaced.