某Q235A钢风扇叶片在运行约180~500 h后发生断裂,采用宏观观察、化学成分分析、扫描电镜和能谱分析、金相检验、硬度测试等方法分析了其断裂原因。结果表明:开裂起源于叶片根部两侧焊缝边缘的热影响区,在风扇转动和发电机整体振动产生的交变应力和焊接应力作用下,裂纹萌生并扩展,最终导致叶片发生断裂。

The fan blades of a Q235A steel cracked after running for about 180-500 h. The reason of cracking was analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, metallographic examination and hardness test. The results show that the crack originated from the heat affected zone at the weld edge on both sides of the blade root. Under the action of alternating stress and welding stress generated by the rotation of the fan and the overall vibration of the generator, the crack initiated and propagated, which eventually led to the crack of the blade.