热电厂锅炉主蒸汽安全阀密封面开裂原因分析

Cracking failure of pressurized plane of main steam safety valve in power station boiler

采用扫描电子显微镜(SEM)对电厂铸造高温合金主蒸汽安全阀的断口进行观察,分析了安全阀密封结合面失效断裂的影响因素。结果表明,阀门表面处理层与基体密封结合面存在以沿晶方式扩展的裂纹,其产生原因是在高温高压工作条件下,蠕变孔洞相互聚合形成裂纹源,同时,铸态组织中粗大碳化物与高温氧化环境诱发部件在表面缺陷处应力集中。

The fracture of main steam safety valve made of cast high-temperature alloy in power station was observed by scanning electron microscope （SEM）. Influence factors of the failure on pressurized planes of the valve were analyzed. The results show that there are intergranular cracks existing in the pressurized plane between treated surface layer and matrix,the causes for such cracking are creeping holes chaining, and the interaction of casting structure defect and environmental corrosion results in stress concentration under high temperature and high pressure work condition.