Microstructure evolution of a drive shaft spline from an aero-engine fuel pump during fretting wear

Abstract

In the process of transmitting power, the drive shaft splines of an aero-engine fuel pump often cause fretting wear due to the action of high-frequency vibration and torque load, which greatly restricts the service life and reliability of a drive shaft spline. Therefore, to understand the whole process of the fretting wear of a drive shaft spline, the microstructure of the worn surface and subsurface was characterized and analysed. The results show that adhesion, deformation, oxidation and cracking occur on the worn surface of the drive shaft spline. Plastic deformation induces dislocation multiplication that expands into subgrains and transforms into equiaxed nanocrystals. Dislocations generated by these grains in the subsequent plastic deformation will be quickly absorbed by grain boundaries, which reduces the stress concentration caused by dislocation blocks and significantly delays cracking. However, wear cracks tend to form at the interfaces of short rod-like nanocrystals near the worn surface and propagate along grain boundaries, accelerating the spalling of the material. These results provide guidance for the design and use of drive shaft splines.