某电动泵传动轴在使用过程中发生早期断裂，采用断口分析、金相检验、硬度测试、化学成分分析、表面质量检查等方法对传动轴断裂的原因进行了分析。结果表明：该传动轴的断裂模式为疲劳断裂；由于电火花加工工艺设置不当，使传动轴的销孔表面产生了微裂纹，在交变载荷作用下，微裂纹不断扩展直至传动轴发生断裂。

Early fracture occurred in the drive shaft of an electric pump during operation. Fracture analysis, metallographic examination, hardness test, chemical composition analysis, surface quality inspection and other methods were used to analyze the fracture causes of the drive shaft. The results show that the fracture mode of the drive shaft was fatigue fracture. Due to the improper setting of electric discharge machining (EDM) technology, micro cracks generated on the pinhole surface of the drive shaft, and the micro cracks propagated continuously until the drive shaft fractured under the action of alternating load.