Failure analysis of planetary gear in wind turbine gearbox

In this article, the chemical composition, microstructure, morphology and micro-component of the fracture are analyzed and tested by chemical composition analysis, metallographic observation, scanning electron microscopy and energy spectrum microcomponent analysis. The results show that the nitrogen content of the planetary wheel is slightly higher than the upper limit, and the local nitrogen content is higher. Improper heat treatment is easy to cause material brittleness, which will significantly reduce the impact toughness of the material. The inner surface of the bearing hole of planetary gear is low in hardness and strength. And it has manufacturing defects and is subject to alternating load, which is easy to cause high cycle fatigue damage of planetary gear. In the process of heat treatment carburizing, the carburizing phenomenon of the lifting hole position of the planetary wheel is not effectively protected, which increases the possibility of micro-cracks in the lifting hole.