针对水环真空泵轴频繁发生断裂的问题，对泵轴进行了宏观观察、金相检验、扫描电镜及能谱分析。结果表明：泵轴断裂的主要原因是在含有氯、氮等元素介质的环境下，泵轴螺纹退刀槽附近缝隙处存在Cl^-局部富集，加速了腐蚀；同时在应力集中和疲劳交变载荷的联合作用下，泵轴产生裂纹并逐渐扩展直至断裂。

Aiming at the problem of frequent fracture of water ring vacuum pump shaft, the fracture causes of the pump shaft were analyzed by macro observation, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that the main reason for the fracture of pump shaft was that in the environment containing elemental media such as chlorine and nitrogen, there was local enrichment of Cl^- in the gap near the thread undercut of pump shaft, which accelerated the corrosion. At the same time, under the combined action of stress concentration and fatigue alternating load, cracks on pump shaft were produced and extended to fracture.