Causes Analysis on Fracture of One Forced Draft Fan Blade of One Supercritical Power Station Boiler

A forced draft fan blade of one power plant fractured when the supercritical boiler was running. The fractured forced draft fan was detected and analyzed synthetically by means of macrographic inspection, metallographic inspection, hardness test, and fracture microzone analysis. The results show that there were many casting flaws in surface and body of the blade, especially the cracks which extended from shrinkages pipes seriously reduced the anti-fatigue capacity of the blade. The fatigue sources originated from the positions of casting flaws would extend under long period cycle load until the blade was broken.