汽轮机中压调速汽门门杆断裂分析

Fracture Analysis of Turbine IP Governor Stop Pole

某电厂汽轮机中压调速汽门门杆发生断裂,采用断口分析和性能分析等方法对门杆的断裂原因进行了分析。结果表明:门杆断裂位置渗氮时未做防护,渗氮后会使此处脆性增加,进一步加剧了应力集中效应,门杆中心的压力平衡孔严重偏离门杆中心,使门杆受力时形成偏载,门杆是在交变冲击载荷、偏载和应力集中效应的共同作用下形成裂纹源,裂纹扩展至临界裂纹尺寸时发生疲劳断裂。

A turbine IP governor stop pole of a power plant fractured. The reasons of the fracture were analyzed by using crack analysis and property analysis. It indicated that the fracture place was not protected when nitriding, its brittleness increased after nitriding, then it aggravated stress concentration effect. The pressure center hole of the pole deviated from its center seriously, it lead to partial load when the pole bearing pressure. The forming of crack source was affected together by alternating impact load, partial load and stress concentration effeet. The fatigue fracture happened when the crack extended to its critical size.