烟气轮机动叶片断裂原因分析

本文分析了某烟气轮机动叶片失效原因。通过使用金相、扫描电镜等手段，对叶片进行裂纹、断口、组织及成分分析。结果表明，该烟气轮机动叶片的断裂性质为疲劳断裂，断裂叶片榫头第三齿（即断口部位）处的接触不均匀造成的严重磨损、接触应力明显增大以及榫齿接触表面存在一定程度的腐蚀损伤是造成叶片榫头发生疲劳开裂的主要原因；断口表面腐蚀产物包含烟气中特有的杂质元素，如Al、Si、Ca、K、S、O、Na等元素。研究发现，晶界碳化物呈现链状分布，已经发生了晶界弱化现象。叶片裂纹源表面的亚表面处存在的夹杂物和合金的晶界弱化也促进了叶片的开裂。研究结果对于叶片的故障分析及预防具有重要的意义。

Failure Analysis of Gas Turbine Rotor Blades

In this paper, the failure mechanism of the gas turbine rotor blades made of Waspaloy superalloy was analyzed. Crack origin detection, fracture surface and microstructure examination and chemical analysis were carried out by means of optical microscopy, scanning electron microscopy and EDS. The results indicate that the fracture mode of the blades is fatigue fracture. The fatigue cracking of the blade rabbets was mainly caused by heavy wear and stress concentration of the contact face resuhing from non-uniform contact. Corrosion damage of the contact surface was another main cause for the fracture. The corrosion products on the fracture surface contained some elements peculiar to the gas, such as Al, Si, Ca, K, S, O, Na, and so on. In addition, it was found that grain-boundary carbides spread out like chains, which resulted in grain-boundary weakness. Subsurface inclusions near the crack origin and the grain-boundary weakness also promoted the fracture of the blades. These findings are meaningful to the failure analysis and fracture prevention of gas turbine Blades.