17CrNiMo6磨煤机减速机齿轮轴断裂原因分析

17CrNiMo6 pulverizer reducer gear shaft breakage cause analysis

17CrNiMo6是一种常用的轴承用钢,某火力发电厂17CrNiMo6材质的磨煤机减速机齿轮轴发生断裂失效,对断口进行宏观分析、化学元素成分分析、金相组织结构分析以及力学性能(含硬度与冲击功)检验。检验结果表明:轴外表面渗碳层力学性能分布不均,部分区域低于标准值;断口形貌为冲击疲劳断口,设备长期处于高负荷运转条件下,启机时冲击负荷较大引起轮齿处产生裂纹并迅速向轴中心部延伸,最终引起断裂。

17CrNiMo6 is normal steel for bearings. There was an accident that a thermal power plant 's pulverizer reducer gear shaft,made from 17 Cr Ni Mo6,was broken. After macroscopic analysis,chemical element analysis metallographic structure analysis and mechanical property test,it was found that mechanical properties are not evenly distributed on the shaft outside surface carburized layer. Partial area is lower than standard required value. Breakage appears like impact fatigue caused. This equipment worked in high load condition for long period. Impact in start-up caused crack and expended to shaft core,ultimately caused shaft broken.