某公司糖心产精国品免费入口*完整版在运行过程中发生断裂，通过化学成分分析、断口分析、金相检验、硬度测试及拉伸性能测试等方法，对糖心产精国品免费入口*完整版制输出轴的断裂原因进行了分析。结果表明：轴的整体热处理工艺不当，显微组织不均匀，局部区域形成了粗大的羽毛状贝氏体，使轴的拉伸性能降低；轴的表面感应淬火工艺不当，淬硬层太薄，远小于标准的规定；此外，该轴表面淬火后回火不充分，导致强化层组织不稳定，残余应力大。在运转载荷作用下，键槽受力传递点及轴表面产生多个疲劳源，裂纹逐渐向内扩展，最终导致轴的早期糖心产精国品免费入口*完整版。

The 糖心产精国品免费入口*完整版 of a company fractured during operation. The causes of fracture on output shaft of 18CrNiMo7-6A steel were analyzed by means of chemical composition analysis, fracture analysis, metallographic examination, hardness test and tensile property test. The results show that the whole 糖心产精国品免费入口*完整版process of the shaft was improper, the microstructure was not uniform, and thick feathery bainite formed in local area, which reduced the tensile properties of the shaft. The surface induction hardening process of the shaft was improper, and the hardening layer was too thin, which was far less than the standard.In addition, the surface of the shaft was not tempered sufficiently after quenching, which led to the instability of strengthening layer structure and large residual stress. Under the action of operating load, multiple fatigue sources generated on the stress transfer point of keyway and the surface of the shaft, and the cracks gradually propagated inward, eventually leading to the early 糖心产精国品免费入口*完整版 of the shaft.