采用宏观分析、化学成分分析、拉伸试验、硬度测试、金相检验、断口分析以及有限元受力分析等方法，对真空泵主轴键槽和平键严重变形失效原因进行了分析。结果表明: 主轴键槽和平键挤压变形严重，主要是因为平键与键槽之间配合间隙过大，在泵的开、停瞬间引起键槽和平键之间形成很大的冲击作用;而且平键的硬度明显低于主轴的硬度，这种偏差很容易造成平键的损伤，使键槽与平键之间的间隙增加，加剧了键槽和平键的变形进程; 主轴键槽变形严重处导致局部应力集中并引发脆性开裂裂纹。

The serious deformation failure of spindle keyways and flat keys of a vacuum pump was researched by macroscopic observation, physical and chemical performance analysis, microscopic observation and finite element force analysis. The results show that the severe compressional deformations of the spindle keyways and flat keys was mainly caused by the great impact action between the keyways and flat keys at starting and stopping instant of the pump because of the big gap between them. Besides, the hardness of the flat keys was obviously lower than that of the spindle, and the hardness difference could easily cause damage on the flat keys and make the gap between the keyways and flat keys even larger, which aggravated the deformation. Brittle cracking happened at the severe deformation positions of the keyways because of local stress concentration caused by the severe deformation.