某电厂给水泵汽轮机末级动叶片断裂分析

Fracture Analysis on the Last Stage Rotating Blade of Steam Turbine of Feed Water Pump in a Power Plant

分析某电厂给水泵汽轮机末级动叶片发生断裂的原因,对断裂叶片进行宏观检查、化学成分分析、力学性能试验、金相检验,对断口位置进行宏观检查、扫描电镜检验、能谱分析.结果表明:给水泵汽轮机末级动叶片断裂模式为高周疲劳断裂.叶片在较高的交变应力的反复作用下萌生疲劳裂纹.叶片表面及断口源区腐蚀的凹坑降低了叶片强度,加速了裂纹萌生,最终导致疲劳断裂.

An analysis was conducted on the fracture of the last stage rotating blade of the steam turbine of feed water pump in a power plant through the macroscopic inspection,chemical composition analysis,mechanical properties test,metallographic examination for the fracture blade,and the macroscopic inspection,scanning electron microscopy,energy spectrum analysis for the fracture position.Results show that the fracture of the last stage rotating blade of the steam turbine of feed water pump presents the fracture type of high-cycle fatigue.The genenration of the crack is caused by the repeated action of the higher alternating stress.The genenration of the crack is promoted with the reduced strength of blade resulted from the corrosion pits on the blade surface and fracture source area,which finally leads to the fracture.