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某火电厂汽轮机组在运行过程中,叶片发生断裂。为了分析叶片断裂原因,对断裂叶片进行宏观检查与分析、化学成分分析、硬度测试试验和金相显微组织观察与分析。结果表明:由于叶根内弧面存在表面损伤,加剧叶片振动,且叶根凹形槽下台阶是应力集中区,疲劳裂纹源在该处产生并逐渐扩展,导致叶片疲劳断裂;断口疲劳源区和疲劳裂纹扩展区所占面积大约为整个断口面积的三分之二,表明叶片断裂属于高周疲劳断裂。
A thermal power plant steam turbine during operation, the blade rupture. In order to analyze the cause of leaf fracture, the macroscopic examination and analysis of the fractured leaf, chemical composition analysis, hardness test and metallographic microstructure observation and analysis were carried out. The results show that fatigue damage occurs on the blade due to the surface damage of the inner surface of the blade root, which aggravates the vibration of the blade and the step below the concave root groove is the stress concentration zone. And fatigue crack growth area occupy about two-thirds of the entire fracture area, indicating that the blade rupture belongs to the high-cycle fatigue fracture.